Australian Soil and Land Survey Field Handbook (Australian Soil and Land Survey Handbooks Series)

Australian Soil and Land Survey Field Handbook third edition The National Committee ON Soil and Terrain

Australian Soil and Land Survey Field Handbook THIRD EDITION

Australian Soil and Land Survey Field Handbook THIRD EDITION

THE NATIONAL COMMITTEE ON SOIL AND TERRAIN

© CSIRO 2009 All rights reserved. Except under the conditions described in the Australian Copyright Act 1968 and subsequent amendments, no part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, duplicating or otherwise, without the prior permission of the copyright owner. Contact CSIRO PUBLISHING for all permission requests. National Library of Australia Cataloguing-in-Publication entry Australian soil and land survey field handbook. 3rd ed. Collingwood, Vic. : CSIRO Publishing, 2009. 9780643093959 (pbk.) Australian soil and land survey handbooks ; no. 1 Includes index. Bibliography. Landforms – Australia – Classification – Handbooks, manuals, etc. Soil surveys – Australia – Handbooks, manuals, etc. Land use surveys – Australia – Handbooks, manuals, etc. Vegetation classification – Australia – Handbooks, manuals, etc. 631.4794 First edition 1984; Second edition 1990 Published by CSIRO PUBLISHING 150 Oxford Street (PO Box 1139) Collingwood VIC 3066 Australia Telephone: Local call: Fax: Email: Web site:

+61 3 9662 7666 1300 788 000 (Australia only) +61 3 9662 7555 [email protected] www.publish.csiro.au

Front cover image (by Linda Gregory): soil landform elements overlaid on shaded elevation. Data sources: Hook R, McPherson A, Glover M, McKenzie NJ, Aldrick J (2002) Land and soil survey, Simmons Creek Catchment, Walbundrie, NSW; and AAM Geoscan (2001) Airborne laser scanning survey of the Simmons Creek Catchment area, 10 m digital elevation model. Set in 10/13 Adobe Palatino and Adobe Sabon Edited by Alexa Cloud Cover and text design by James Kelly Typeset by Desktop Concepts Pty Ltd, Melbourne Printed in China by 1010 Printing International Ltd CSIRO PUBLISHING publishes and distributes scientific, technical and health science books, magazines and journals from Australia to a worldwide audience and conducts these activities autonomously from the research activities of the Commonwealth Scientific and Industrial Research Organisation (CSIRO). The views expressed in this publication are those of the author(s) and do not necessarily represent those of, and should not be attributed to, the publisher or CSIRO.

CONTENTS

Preface to the first edition

xi

Preface to the second edition

xiii

Preface to the third edition

xiv

Acknowledgements

xvii

Purpose and use of handbook

J.G. Speight and R.F. Isbell

1

Purpose

1

Use

3

The site concept J.G. Speight and R.C. McDonald

5

Location

7

L.J. Gregory, R.C. McDonald and R.F. Isbell

Method

7

State or Territory

7

Coordinates

7

Topographic map sheet

9

Global Positioning System (GPS) Survey

10

Air photo reference

10

General R.C. McDonald and R.F. Isbell

13

Described by

13

Date

13

Annual rainfall

13

Type of site

13

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Australian Soil and Land Survey Field Handbook

Landform

J.G. Speight

15

Landform description

15

Description of landform element

17

Landform element key and glossary

31

Description of landform pattern

44

Landform pattern glossary

55

Vegetation

R.J. Hnatiuk, R. Thackway and J. Walker

73

Overview of the classification

75

Recognising strata

77

Formation (Level 1)

80

Structural formation (Level 2)

88

Broad floristic formation (Level 3) and subdivisions (Levels 4 to 6)

95

Examples of standard classification

102

Wetlands

103

Rainforest

109

Growth stage

120

Condition

120

Land surface R.C. McDonald, R.F. Isbell and J.G. Speight

127

Aspect

127

Elevation

127

Drainage height

128

Disturbance of site

128

Microrelief

129

Erosion

133

Aggradation

138

Inundation

138

Coarse fragments

139

Rock outcrop

143

vi

Contents

Depth to free water

144

Runoff

144

Soil profile

R.C. McDonald and R.F. Isbell

147

Type of soil observation

147

Horizons

148

Depth of horizons

156

Depth to R horizon or strongly cemented pan

156

Colour

159

Mottles and other colour patterns

159

Field texture

161

Coarse fragments

170

Structure

171

Fabric

181

Cutans

182

Voids

184

Soil water status

186

Consistence

186

Condition of surface soil when dry

189

Water repellence

191

Pans

192

Segregations of pedogenic origin

195

Effervescence of carbonate in fine earth

198

Field pH

198

Roots

199

Boundaries between horizons

199

Soil water regime

200

Substrate

J.G. Speight and R.F. Isbell

Properties of substrate material

205 206

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Australian Soil and Land Survey Field Handbook

Properties of substrate masses

210

Genetic type of substrate masses

216

Glossary of substrate mass genetic types

219

Appendix 1: Soil taxonomic units R.F. Isbell and R.C. McDonald

225

The Australian Soil Classification

225

Soil Taxonomy

227

World Reference Base for soil resources (WRB)

226

References

229

Index

240

viii

Correct citation: If reference is made to the Handbook as a whole, give reference as follows: s in text National Committee on Soil and Terrain (2009) s in references National Committee on Soil and Terrain (2009) ‘Australian soil and land survey field handbook (3rd edn).’ (CSIRO Publishing: Melbourne). If reference is made to a specific section e.g. Landform, give reference as follows: s in text Speight (2009) s in references Speight JG (2009) Landform. In ‘Australian soil and land survey field handbook (3rd edn).’ (National Committee on Soil and Terrain) (CSIRO Publishing: Melbourne). The Handbook was prepared under the auspices of the National Committee on Soil and Terrain with funding and support from CSIRO, the Natural Heritage Trust and the Bureau of Rural Sciences.

PREFACE TO THE FIRST EDITION

The use of a standard terminology for the characterisation of site attributes, such as landform and vegetation, and for the description of soils has obvious benefits for the various organisations in Australia concerned with soil and land survey investigations. Some uniformity in the description of soils has been achieved over the years with the publication of Soil survey manual (Soil Survey Staff 1951), Guidelines for soil description (FAO 1968) and, in Australia, A factual key for the recognition of Australian soils (Northcote 1971). In 1975 the Standing Committee on Agriculture established a Working Party to enquire into the nature and prosecution of soil surveys in Australia, with the aim of generating a satisfactory degree of uniformity. This Working Party was convened by Dr E.G. Hallsworth, Chairman of the then CSIRO Land Resource Laboratories, and comprised representatives of these laboratories and appropriate State and Commonwealth authorities. The Working Party recommended the formation of a National Soil and Land Survey Committee1; one of its functions would be the production of an Australian soil and land survey handbook, which would set down standards of terminology and methodology for the survey of all components of land resources. In 1976 the Standing Committee on Agriculture considered the Working Party report and requested that an Expert Panel advise further on ways of producing such a handbook. This Expert Panel, convened by Dr E.G. Hallsworth and comprising members of State and Commonwealth authorities, met in April 1977. It proposed that a committee of three should develop interim standards of soil and land classification and mapping capable of general application and produce a handbook of standard terminology and methodology. The members of the committee were R.C. McDonald, R.F. Isbell and J.G. Speight. It was originally proposed that the committee would devote not less than 12 months full time to the project. This was not possible, and the members have accordingly devoted their available time to producing this Australian soil

1

This was established as a subcommittee of the Standing Committee on Soil Conservation in 1979 and renamed Australian Soil and Land Resources Committee in 1981.

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Australian Soil and Land Survey Field Handbook

and land survey field handbook. J. Walker and M.S. Hopkins were invited to contribute the section on vegetation. The first draft was based largely on similar handbooks, namely: s s s s

Soil survey manual (Soil Survey Staff 1951) Guidelines for soil description (FAO 1968) A factual key for the recognition of Australian soils (Northcote 1971) Soil survey field handbook (Hodgson 1974) for the Soil Survey of England and Wales s the fifth unpublished draft of the revised United States Department of Agriculture Soil survey manual s The Canada Soil Information System (Can SIS) manual for describing soils in the field (Canada Soil Survey Committee 1978). Because there was considerable divergence of approach (for example, in setting class limits) for many attributes, it was frequently necessary to judge which particular arrangement was most appropriate to Australian conditions. The first draft was sent for comment to 116 people representing all relevant organisations in Australia. The 87 replies provided a good representation of ideas. The second draft was also widely circulated and attracted a further range of comment. Because of the diversity of environments and the nature of the organisations concerned with land and soil investigations in Australia, consensus was not possible for some of the attributes discussed in this Handbook. In most such cases the majority view was adopted. The suggested field observations encompass a range in convenience of measurement and in relevance both to practical problems of land use and the scientific study of land and soil. Progress towards the establishment of a more relevant suite of attributes will depend to a degree on the use of more systematic methods in the recording of field observations, in order to permit the testing of the underlying, often unstated models. Thus, the use of this Handbook may hasten the development of more concise or more relevant field observations than those recommended in it. Such efforts to improve survey techniques must go hand in hand with efforts to discover from the clients their precise needs.

xii

PREFACE TO THE SECOND EDITION

Since the first edition in 1984 the Handbook has been widely used and adopted as a standard throughout Australia. When the publishers suggested a second edition, a request was made to relevant organisations in Australia for comments and possible modifications on the basis of field use. Numerous responses reflect the actual experiences of users since 1984. Some 23 individual replies were received, as well as three comprehensive submissions from the New South Wales Soil Data System Working Group, the New South Wales Department of Agriculture, and the Victorian Department of Conservation, Forests and Lands. The Australian Surveying and Land Information Group, Department of Administrative Services, Canberra gave useful advice on map references. While it was not possible to adopt every suggestion made, the comments have helped to make this second edition much clearer and more consistent. We thank these respondents for their assistance. In this edition a number of new sections have been added, and some rearrangements have been made to facilitate use. In particular, a much expanded chapter on substrate has been included. This should help cater to the needs of non-agricultural users. Throughout this revised edition we have tried to keep code changes to a minimum. The use of a standard terminology for the characterisation of landform and vegetation, and for the description of soils, appears to have been of benefit to scientists in Australia concerned with soil and land survey investigations. We believe that there will be an even wider acceptance of this second edition.

xiii

PREFACE TO THE THIRD EDITION

The Australian soil and land survey field handbook is a primary reference for soil scientists, ecologists, geomorphologists and students. The Handbook has been a remarkable success. During the last 25 years, consistent data have been collected on vegetation, landform and soils across Australia and the resulting databases are far more comprehensive and useful than would have otherwise been the case. Many field technicians and scientists have learnt their craft with the aid of the Handbook and it continues to sell at a steady rate. However, this success creates several significant challenges. The Handbook is essentially a measurement system for recording the attributes of landform, vegetation and soil in a semi-quantitative manner and with minimal instrumentation. Measurement systems have changed dramatically in recent years and an account of the most significant developments is provided in the new Guidelines for surveying soil and land resources (McKenzie et al. 2008). For example, digital terrain analysis has replaced some aspects of air photo interpretation and landform classification, and proximal sensing (e.g. soil spectroscopy in the visible through to the mid-infrared range of the electromagnetic spectrum) is starting to replace conventional soil description. These methods will be deployed in routine surveys during the next few years and so a completely new Handbook will be required.

Changes in this Edition Any change to the Handbook forces major overhauls of existing databases and the consequences can be far reaching and expensive. At the same time, the Handbook must reflect current technology otherwise it is destined to become irrelevant. The National Committee on Soil and Terrain faced these dilemmas when stocks of the Second Edition ran out. We knew that a complete revision of every aspect of the Handbook was needed but that new copies had to be printed immediately. We decided to publish the Third Edition only with changes that could be made with relative ease. The changes are as follows. s Most significant is revision of the vegetation chapter. As vegetation is outside the scope of the National Committee on Soil and Terrain, this xiv

Preface to the Third Edition

chapter has been guided instead by the Executive Steering Committee for Australian Vegetation Information (ESCAVI). ESCAVI has endorsed this chapter as guidelines for the collection of site-based data on vegetation in Australia. The field data collected with these new methods are currently classified, coded and named differently than in the National Vegetation Information System (NVIS) framework (ESCAVI 2003). Starting in 2008, NVIS will progressively be changed to match the classification in this chapter. Chapter 6 ‘Vegetation’ has been expanded to include wetlands, temperate rainforests, vegetation growth stage and vegetation condition. Other changes include new height classes, an increased number of broad floristic groups, and different codes for some attributes. The terms used to name vegetation units, based on their cover and broad floristic composition (Table 21), have been changed. Details of the rationale for these changes can be found in Hnatiuk et al. (2008). s Chapter 3 ‘Location’ has been updated to accommodate GPS survey and datum information. The State and Territory codes have been changed. s Chapter 5 ‘Landform’ includes new landform elements, namely: hummocky dune, barchan dune, parabolic dune, linear or longitudinal dune, risecrest, riseslope, residual rise, deflation basin, solution doline, and collapse doline.

Future changes The Fourth Edition will need to incorporate results from current research and provide guidance on several new technologies. The main challenges apparent at this stage are as follows. s The site concept which forms the basis for landform description will need revision to ensure it is consistent with contemporary methods for digital terrain analysis, spatial analysis and Earth-system science. s Gary Speight’s system for measuring and classifying landform was pioneering and many of his ideas have been incorporated into recent methods for digital terrain analysis. A new system for characterising landform is needed that takes full advantage of the new technology while retaining the link to geomorphic processes. This will be a major challenge. xv

Australian Soil and Land Survey Field Handbook

s High-resolution digital elevation models and new forms of remote sensing promise to replace the qualitative descriptors of land surface presented in this edition. Extensive testing across a range of environments is needed to identify robust descriptors. s As noted earlier, rapid advances in proximal sensing are starting to provide a practical alternative to conventional descriptions of soil morphology. Considerable field testing and further research will be needed before agreement can be reached on a new minimum data set for characterising soil profiles in the field. Database systems will require a major overhaul. s Closely related to proximal sensing is the advent of systems for automatic data entry via various forms of telemetry. Again, guidelines are required on data models, minimum data sets and transfer protocols.

xvi

ACKNOWLEDGEMENTS

Acknowledging the many contributors to the Handbook is becoming increasingly difficult. The Handbook is a collective effort and overall authorship now rests with the National Committee on Soil and Terrain. Several of the original authors have retired (Gary Speight, Joe Walker and Mike Hopkins) or sadly died (Ron McDonald and Ray Isbell) since the initial publication in 1984. However, we have retained their names on contributions that remain essentially intact. Joe Walker has also retired but he kindly contributed to the major revision of the vegetation chapter in collaboration with Roger Hnatiuk and Richard Thackway (Bureau of Rural Sciences). Linda Gregory (CSIRO) revised the chapter on site location. Specific inputs on landform and substrate were provided by David Maschmedt (South Australian Department of Water, Land and Biodiversity Conservation) and Colin Pain (Geoscience Australia). Other members of the National Committee on Soil and Terrain assisted with the production process, most notably Noel Schoknecht (Western Australian Department of Agriculture and Food) and Neil McKenzie (CSIRO). Greg Rinder expertly prepared the figures and David Jacquier helped the editorial team. Becky Schmidt (CSIRO) provided excellent editorial input to this edition. The team at CSIRO Publishing once again were exceedingly helpful and very patient. Particular thanks go to Tracey Millen, Ted Hamilton and Briana Melideo.

xvii

PU R P OSE A N D USE OF H A N DBOOK J.G. Speight and R.F. Isbell

PURPOSE This Handbook is intended to contribute to the systematic recording of field observations in Australian soil and land surveys. It attempts to: s list attributes2 thought necessary to describe adequately site and soil conditions s define these attributes consistently wherever possible with their use elsewhere in the world but giving particular emphasis to Australian conditions s define terms and categories for landform, vegetation, land surface, soil and substrate material that are based explicitly on the specified attributes s suggest codings for the various attributes, terms and categories so that concise recording systems may be developed for field use. A further purpose of the Handbook is to provide a factual database from which interpretations can be made. Field observations provide the basis for predicting the consequences of land use. These may be supplemented by data 2

No distinction is made between the word ‘attribute’ and the word ‘property’ used in the Soil Profile section. Both mean ‘characteristic’ or ‘trait’. ‘Attribute’ includes ‘variable’. Observations produce values of attributes or properties.

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Australian Soil and Land Survey Field Handbook

from air photos, maps, records, laboratory analyses, experiments, local information and so on. The chain of inference for making such predictions has been clearly established in only a few instances, evidence that perhaps the weakest link is the collection of relevant field data. This Handbook was prepared to meet the needs of somewhat diverse surveys. The Handbook covers a range of soil surveys, typically at medium and small scales, and ‘land system’, ‘land unit’, ‘biophysical’, ‘ecological’ and ‘environmental impact’ surveys, whether for agricultural, recreational, industrial, residential or other purposes such as a general scientific inventory. The observations proposed are relevant to surveys at diverse scales, although surveys at very large scales commonly demand both more detailed observations, and also observations of particular attributes that probably have not been included here. At such large scales, many attributes of the site that surrounds each point of soil observation may be uniform over most of the points, and thus is of little interest within the context of the given survey. However, if site attributes are recorded for at least a few of the observation points, they may prove extremely valuable in later correlative work. The recording of attributes of the site and adjacent landforms has two distinct purposes. First, the attributes may be directly relevant to land use – for example, to ploughing feasibility, earthmoving costs, erosion hazards, scenic resources and costs of clearing. Second, the attributes are a link between the hidden physical and chemical properties of the soil, regolith or bedrock, for which data will always be scarce, and the visible properties of landform, surface material, and vegetation that may be more readily mapped and catalogued. Site attributes link to other attributes both within a site and beyond it. Attributes are intended to be correlated with soil and other subsurface properties observed at the site in order to discover significant relationships between them. Relationships implied in some surveys have lacked adequate support (Bleeker and Speight 1978; Chittleborough 1978). Better validation is required to justify extrapolative mapping and the setting up of land units or land components. The site data, however, are intended to establish local ‘ground truth’ values for the landform, surface material and vegetative properties that contribute to the more extensively developed characteristic image, ‘signature’, or pattern on an air photo or other remote-sensing record.

2

Purpose and Use of Handbook

USE The Handbook is designed as a reference to attributes needed to describe systematically the site and soil conditions related to landform, vegetation, land surface, soil profile and substrate materials. The glossaries and definitions of terms will provide a uniform understanding of the meaning of words used in field notes, in discussion and in publications. This will enhance communication. The attributes are to form the basis of lists to be used for specific surveys. When developed, these lists will provide sufficient information to support the survey conclusions. For each attribute, there is a suggested scheme of classes, but this does not preclude the observation and recording of actual numerical values where feasible. Suggested code letters and numbers for each attribute described appear in red. Not all conceivable soil properties are provided for and hence some properties may need to be recorded, if desired, in free format – for example, orientation of mottles. All dimensions are expressed in SI units. The attributes to be recorded in a specific survey will depend on its purpose and scale and will be decided upon by the organisation conducting the survey. In reconnaissance surveys, fewer site and profile attributes will be described than in high-intensity surveys. For detailed site and profile descriptions such as those required for pedological research, descriptions of agronomic research sites or in the legend-making stage of detailed surveys, most of the attributes given in this Handbook will be recorded, if present. It is important that sites and profiles be described as they are and not as they may have been. Sites and profiles should be described as factually as practicable but genetic inferences are inevitable. Where genetic inferences are used, the basis of the inference should be noted so the user is aware of assumptions made. The field observations are for the descriptions of sites (page 5) and not for soil classes or for aspects of mapping units that are better recorded in the office rather than in the field. Although diagnostic horizons necessary for particular soil classification systems, for instance Soil Taxonomy (Soil Survey Staff 1975), are not included, the field observations recorded may be used to classify soil in this or in any other soil classification scheme. Coding for soil classification schemes most likely to be used in Australia is given in Appendix 1.

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Australian Soil and Land Survey Field Handbook

Most of the attributes of soil to be observed, horizon by horizon, are widely accepted among pedologists. However, there are some that do not have direct relevance to land use; rather, they serve as surrogates for properties that are impractical to observe or measure routinely.

4

T H E SI T E C ONC E P T J.G. Speight and R.C. McDonald

A site is a small area of land considered representative of the landform, vegetation, land surface and other land features associated with the soil observation. The extent of a site is arbitrary but certain dimensions are appropriate for certain attributes. Observe landform element attributes over a circle of 20 m radius (1256 m 2) and landform pattern attributes over a circle of 300 m radius (28.3 ha). Sample vegetation in a square or rectangular site of 400 m2. In sites dominated by ground layer, several 20–50 m2 samples or 10–20 m transects are used. Observe most land surface attributes within a site 10 m in radius (315 m2); these attributes are: slope, aspect, disturbance of site, microrelief, surface coarse fragments, rock outcrop and runoff. A few land surface attributes refer simply to the point of soil observation, namely elevation, drainage height and depth to free water; the attributes erosion, aggradation and inundation refer to the larger 20 m radius site used for landform element attributes. In some instances a soil observation may be representative only of a soil body smaller than 10 m in radius. For example, in some gilgai the vegetation, land surface and soil all differ between the mound and depression. In such instances the extent of the site for those features is only that of the mound or the depression.

5

LOC AT ION L.J. Gregory, R.C. McDonald and R.F. Isbell

METHOD Record the method used to acquire the coordinates. R G S

Map reference GPS Survey

STATE OR TERRITORY Record the code as follows for the State or Territory in which the site is described. These codes have been changed from McDonald and Isbell (1990). 1 2 3 4

NSW VIC QLD SA

5 6 7 8

WA TAS NT ACT

COORDINATES Datum Record the datum of the coordinates. Older maps will generally be based on the Australian Geodetic Datum of 1966 or 1984 (AGD66, AGD84), while current maps should be based on the Geocentric Datum of Australia (GDA94). If you

7

Australian Soil and Land Survey Field Handbook

are obtaining coordinates from a Global Positioning System (GPS) unit, the native datum is the World Geodetic System (WGS84). However, this may not be the display default so check the settings. For further information, see the Geocentric datum of Australia technical manual (Intergovernmental Committee on Surveying and Mapping 2002). AGD66 AGD84 GDA94 WGS84

Australian Geodetic Datum 1966 Australian Geodetic Datum 1984 Geocentric Datum of Australia 1994 World Geodetic System 1984

Projection State whether the coordinates are projected or geographic. M

Projected by Universal Transverse Mercator system Geographic (latitude and longitude)

L

Projected Most topographic map sheets are projected onto the Universal Transverse Mercator (UTM) coordinate system. In Australia, this will be called the Australian Map Grid (AMG) or the Map Grid of Australia (MGA) depending on the datum used. The easting and northing coordinates taken from these sheets will have 6 digits and 7 digits respectively. The zone will also be required (49–56 in Australia). Do not use the Universal Grid Reference notation.3

Geographic When using a GPS or a regional map, record coordinates in latitude and longitude. Record southern hemisphere latitudes as negative.

Easting, northing, zone Record easting and northing UTM projected coordinates, when reading from a topographic map. Give a 6-figure easting, a 7-figure northing and a 2-figure grid 3

The Universal Grid Reference (National Mapping Council of Australia 1986) uses a zone designator and 100 000 metre square identification along with a reduced set of digits. The example given in the section ‘Easting, northing, zone’ (see page 9) would be recorded as 55HFA9208494905 (‘55H’ is the zone designator while ‘FA’ is the 100 000 metre square identification).

8

Location

zone (49–56 in Australia), as accurately as map scale permits. Location of the central point of a site on a map is unlikely to be much more accurate than 1 mm on the map (i.e. 10 m on a 1:10 000 scale map, or 100 m on a 1:100 000 scale map). Example: Zone 55

Easting 692084

Northing 6094905

Latitude and longitude Coordinates may be given in degrees, minutes and seconds (DMS) where a location is read from a small-scale (regional) map. When locating with a GPS, record the coordinates in decimal degrees (DD) to five places to obtain a precision to the metre. Latitudes (giving the north or the south part of the coordinate) will be negative in Australia. Example: Latitude –35.27058

Longitude 149.11181

TOPOGRAPHIC MAP SHEET Give map sheet details regardless of the method used to obtain the coordinates. This will provide a cross-check for attribute accuracy. At scales larger than 1:100 000, use the numbering system for the State or Territory in which the survey is conducted.

Map scale 1 2 3 4

1:1 000 1:2 500 1:5 000 1:10 000

5 6 7 8

1:25 000 1:50 000 1:100 000 1:250 000

Map sheet number and map sheet name Give number and name on the map, for example:

9

Australian Soil and Land Survey Field Handbook

Map scale Map sheet number Map sheet name

8 SH 50-15 Kellerberrin

7 8525 Kosciuszko

6 8727-III Canberra

GLOBAL POSITIONING SYSTEM (GPS) SURVEY Record the GPS survey method used to obtain the coordinates and estimate the accuracy. Make sure you also record the datum and projection settings in the appropriate section. Submetre accuracy is usually obtained only through the use of differential techniques. Autonomous (single unit) methods can obtain <15 m accuracy under optimal conditions. Understand the limitations of the equipment and the various factors that will affect the accuracy.

GPS method S D

Single unit GPS Differential GPS

Accuracy estimate 1 2 3 4 5

<1 m 1–5 m 5–15 m 15–30 m >30 m

AIR PHOTO REFERENCE Film number Give film number on photo, for example: CABC/C/999 or NSW 2719

Run number Give number of run.

10

Location

Frame number Give number of the individual photo.

Site reference East (mm) North (mm) Give position of site on photo in millimetres east from western edge of the photo and north from southern edge. It is strongly recommended that the site should be marked on the air photo by pricking through the print and writing the site number on the back.

11

GEN ER AL R.C. McDonald and R.F. Isbell

DESCRIBED BY Give first three letters of surname and one initial, for example: NORK

for K.H. Northcote

DATE Give date profile described, for example: 23 December 1989, as 231289

ANNUAL RAINFALL Give mean annual rainfall, in millimetres, from nearest recording station or climate surface.

TYPE OF SITE G F

Grid site Free survey site

13

L A N DFOR M J.G. Speight

LANDFORM DESCRIPTION The description of landform in soil and land surveys has several purposes: s it has direct application to land use planning s the description is useful for finding relationships to support the extrapolation of point observations s it helps to predict the land degradation that may follow various land uses. Also, landform description often permits the reader to identify the part of terrain under discussion. Landform description and classification have scarcely developed far enough in any country to meet the needs of land use planning (Lynch and Kolenbrander 1981). The scheme that follows is intended to produce a record of observations rather than inferences. Where inference is implied in geomorphological terminology and practice, a clear record of what has been inferred is presented. In this technique for describing landforms, the whole land surface is viewed as a mosaic of tiles of odd shapes and sizes. To impose order, the mosaic is treated as if the tiles are of two distinct sizes, the larger ones being themselves mosaics of the smaller ones. The larger tiles, more than 600 m across, are called landform patterns. About 40 types of landform pattern are defined. They include,

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Australian Soil and Land Survey Field Handbook

for example, flood plain, dunefield and hills. The smaller tiles, which form mosaics within landform patterns, are about 40 m or more across. These are called landform elements. Among more than 80 defined types of landform element are included, for example, cliff, footslope and valley flat. Landform elements and landform patterns are described and classified into named types by the values of their landform attributes. Distinct suites of landform attributes relate to landform elements and landform patterns, respectively. Slope and position in a toposequence are key attributes for landform elements. Relief and stream occurrence describe landform patterns.4 Each of these two landform units is an integral part of a land unit defined in the companion handbook Guidelines for surveying soil and land resources (McKenzie et al. 2008). A landform element is the landform part of a land facet, and a landform pattern is the landform part of a land system. Maps to display units based on landform can show either landform elements or landform patterns. For each map scale, a unit that is narrower than about 3 mm on the map cannot be read easily. Landform patterns have a characteristic dimension of about 600 m. This is the recommended size for sampling the landform pattern to evaluate its attributes. It is also the normal minimum width of a mapped landform pattern. It follows that landform patterns are best shown on a map at 1:200 000 scale. Landform elements, with a characteristic dimension of about 40 m, are best shown at 1:15 000 scale. Table 1 shows which of these two units is more appropriate on maps of various scales. Both landform elements and landform patterns may extend over areas very much larger then their characteristic dimensions. Since many relationships between landforms and other phenomena occur at the landform element level, this model should be used to describe landform even when the scale dictates that only landform patterns can be mapped. In the field, describe both landform element and landform pattern. In air photo interpretation and mapping, find the proportional occurrence and distribution of landform elements within each landform pattern. An even smaller sampling area of 10 m radius is convenient for field observation of certain attributes of landform and other features covered in the chapter ‘Land surface’ (page 127); see also ‘The site concept’ (page 5).

4

Landform patterns and landform elements are formally defined in the abstract of Speight (1974) and are discussed in Speight (1976, 1977).

16

Landform

Table 1 Appropriate landform model for mapping at various scales Map scale

Minimum width of mapping units

Appropriate landform model for mapping

1:500 000

1500 m

Landform pattern

1:250 000

750 m

Landform pattern

1:100 000

300 m

Landform pattern

1:50 000

150 m

Landform pattern

1:25 000

75 m

Landform pattern/landform element

1:10 000

30 m

Landform element

1:5 000

15 m

Landform element

How much detail? The attributes listed below are those required to distinguish between the types of landform given in the glossaries. The distinctions that have been made routinely in the past are likely to form a sound basis for survey practice. For tasks where landform is of little concern, a very brief form of description is specified (pages 26 and 46). Some of the attributes are expressed in grade scales, with classes of even sizes, usually on a logarithmic base. Where more rigorous analysis is feasible, numerical values of attributes should be observed. Various additional attributes capable of precise quantification may be devised.

DESCRIPTION OF LANDFORM ELEMENT A landform element may be described by the following attributes, assessed within a circle of about 20 m radius: s s s s s

slope morphological type dimensions mode of geomorphological activity geomorphological agent.

These will establish most of the distinctions between landform elements that are implied by their geomorphological names. The glossary of types of landform element occurring in Australia (page 31) refers explicitly to this set

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Australian Soil and Land Survey Field Handbook

of attributes. A landform element that has been described may thus be assigned a type name. A shorter description consists simply of slope, morphological type, and name (page 26).

Slope Means of evaluation of slope T

Tripod-mounted instrument and staff

A

Abney level or clinometer and tape

P

Contour plan at 1:10 000 or larger scale

E

Estimate

Slope value Express slope tangent as a percentage using up to three significant figures (e.g. 1%, 2.45%, 9%, 12.5%, 115%). Evaluate the slope over an interval of 20 m, straddling the point of soil observation.

Slope class Slope classes are defined in Table 2. The optional word ‘inclined’ is used to distinguish slope from other attributes, for example ‘gently inclined footslope’ from ‘gently undulating rises’, and ‘moderately inclined hillslope’ from ‘moderately spaced streams’. The class boundaries given in Table 2, and repeated in Table 4, are simply boundaries that separate slope terms in common use, adjusted to regular logarithmic intervals. They refer neither to observed natural clustering of slope values, since such clustering has not been shown to occur, nor do they relate precisely to boundary criteria for land use, which may change with advancing technology and which vary arbitrarily between organisations. It may sometimes be advantageous to split each of the classes ‘very gently inclined’, ‘gently inclined’ and ‘moderately inclined’ into two levels, the appropriate boundary values being 1.8%, 5.6% and 18%. There may also be compelling reasons for using other schemes of slope classes. However, schemes that do not have constant class widths from low to high slope values can lead to problems in subsequent statistical work.

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Landform

Table 2 Definition of slope classes (after Speight 1967, 1971) Approximate slope values

Symbol

Slope class

LE

Level

Tangent (%) Boundary

Degrees

Average 0.6

Very gently inclined

GE

Gently inclined

0°35’ 1 1°45’ 6 5°45’ 20

Steep

VS

Very steep

18° 40 30° 70

CL

Cliffed

27.5 37°

100 Precipitous

25.0 23°

56

PR

20.0 10°

32 ST

15.0 3°

10 Moderately inclined

10.0 1°

3

MO

Average 0°20’

1 VG

Boundary

Definitive slope values (altan units) a

45° 170

30.0 60°

300

72° 500

35.0 80°

a Altan θ = 10 log10 (1000 tan θ) (Young 1972, page 137).

Always observe and record the slope as precisely as the chosen survey method permits. The observation should span no less than 20 m (page 17) so as not to be influenced too much by features of the microrelief (page 129) that occur within the landform element.

Morphological type Landform elements fall into morphological types as sketched in Figure 1. Ten types are distinguished:

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Australian Soil and Land Survey Field Handbook

C

Crest

H

Hillock

R

Ridge

S

Simple slope

U

Upper slope

M

Mid-slope

L

Lower slope

F

Flat

V

Open depression (vale)

D

Closed depression

Of these, the types called ‘slope’ are also characterised by their inclination relative to adjacent elements as waxing, waning, maximal or minimal. Crests and depressions form the highest and lowest parts of the terrain. They are defined as follows: Crest

Landform element that stands above all, or almost all, points in the adjacent terrain. It is characteristically smoothly convex upwards in downslope profile or in contour, or both. The margin of a crest element should be drawn at the limit of observed curvature.

Depression

Landform element that stands below all, or almost all, points in the adjacent terrain. A closed depression stands below all such points; an open depression extends at the same elevation, or lower, beyond the locality where it is observed. Many depressions are concave upwards and their margins should be drawn at the limit of observed curvature.

In any terrain, one may draw slope lines at right angles to the contour lines. Slope lines control the direction of many land-forming processes. In a terrain that has relief (page 45), each slope line runs from the extreme top (summit) of a crest down to the extreme bottom (lowest point) of a closed depression (Cayley 1859). Figure 2a shows many slope lines descending from several summits to one low point. The sequence of landform elements down a slope line is called

20

Landform

a toposequence. The position in a toposequence is used to define the morphological types of a slope element that may occur between a crest and a depression. First, the general type is defined: Slope

planar landform element that is neither a crest nor a depression and has an inclination greater than about 1%.

Landform elements that are slopes are treated as if each element is straight, and meets another slope element at a slope break (see Figure 1). Four morphological types are distinguished on their position in a toposequence relative to crests, flats (defined below) and depressions: Simple slope

slope element adjacent below a crest or flat and adjacent above a flat or depression.

Upper slope

slope element adjacent below a crest or flat but not adjacent above a flat or depression.

Mid-slope

slope element not adjacent below a crest or flat and not adjacent above a flat or depression.

Lower slope

slope element not adjacent below a crest or flat but adjacent above a flat or depression.

A toposequence may include no slope element (Figures 1a, c, d), one simple slope (Figures 1b, f, g, h), or an upper slope and a lower slope (Figure 1i). All three cases occur in the area mapped in Figure 2b. More complex toposequences may include an upper slope, a lower slope and one or more mid-slopes (Figures 1e, j). The number of slope elements to distinguish depends either on the chosen level of survey detail or on observed differences in landform and their relationship to soil or vegetation.

Relative inclination of slope elements Although lower slopes are often gentler than upper slopes, they need not be so (Figure 1i). A separate morphological attribute expresses the relative inclination of adjacent landform elements in a toposequence. (Crests and depressions are taken to be gentler than adjacent slopes.)

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Australian Soil and Land Survey Field Handbook

X

Waxing

element upslope is gentler, element downslope is steeper.

N

Waning

element upslope is steeper, element downslope is gentler.

A

Maximal

element upslope is gentler, element downslope is gentler.

I

Minimal

element upslope is steeper, element downslope is steeper.

The morphological types upper slope, mid-slope and lower slope require two codes (e.g. UX, MN) (Figure 1) to include relative inclination. Other morphological types need no second code letter. Simple slopes are always maximal; for crests, flats, depressions, hillocks and ridges, relative inclination does not have a clear meaning. Flats are not included in the above morphological types. They are defined as follows: Flat

planar landform element that is neither a crest nor a depression and is level or very gently inclined (<3% tangent approximately).

As defined, some flats and slopes may have the same inclination (1–3%). They differ in their typical relation to slope lines and toposequences. The slope line on a flat often runs parallel to the course line in a nearby open depression such as a stream channel. The slope line on a slope seldom does so, but makes an angle with the course line (Figure 2a). A slope typically occurs in a toposequence from a crest to a depression. Where a flat occurs in such a toposequence (Figures 1b, e, h), it usually marks a change in process and a sharp change in the direction of the slope line. Most flats are in terrain with very little relief where crests do not occur.

Compound morphological types Several types of landform feature have crests and adjoining slopes that are so small that a 20 m radius site would usually include both. Two compound morphological types are distinguished by the relative length of the crest:

22

Landform

Crest C

Crest C

(a) Crest C

(b)

Simple slope S

Simple slope Open S depression V

(f)

Open depression V

Crest C

Open depression Flat V F

Simple slope S

(g)

V Ridge R

Crest C

Open depression V

Simple slope S

(h)

Open depression

(c) Crest C Ridge R

(d)

(i)

Flat F

Flat F

Waxing upper slope UX Maximal lower slope LA V

Maximal upper slope UA Crest C

(e)

Crest C

(j)

Waning mid-slope MN

Waning lower slope LN

Open depression Maximal upper slope UA Minimal mid-slope MI

Open Flat depression V F

Maximal lower slope LA

V Open depression

Figure 1 Examples of profiles across terrain divided into morphological types of landform element. Note that the boundary between crest and slope elements is at the end of the curvature of the crest. Each slope element is treated as if it were straight.

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Australian Soil and Land Survey Field Handbook

LOW POINT

0

89

0

90

0

87

SUMMIT

PASS

SUMMIT PASS

880

SUMMIT PASS

890

900

Ridge Line

900

Course Line

0

Other slope lines

Metres

100

Figure 2a Slope lines overlaid on a contour map to show ridge lines and course lines where many slope lines come together.

24

Landform

0

89

0

87

Cr es t

Crest

Simple slope Crest depression

Open

Cr

es

t

Closed

depression

0 90

Simple slope Waning lower slope

n

Maximal upper slope

Op

en

de

pr

es

sio

880

890

SIZE OF SITE FOR LANDFORM ELEMENT

40m

900

900 0

Metres

100

Figure 2b A landform pattern of rolling low hills mapped into morphological types of landform element. Note that the crests and depressions in this case are mainly narrower than the recommended site size.

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Australian Soil and Land Survey Field Handbook

Hillock

compound landform element comprising a narrow crest and short adjoining slopes, the crest length being less than the width of the landform element.

Ridge

compound landform element comprising a narrow crest and short adjoining slopes, the crest length being greater than the width of the landform element.

A dune is defined in the glossary as a hillock or ridge but, to allow for large dunes or detailed work, elements called dunecrest and duneslope are also defined. Other types of hillock and ridge may be divided into crest and slope elements if necessary.

Visualisation When selecting a field site, visualise the set of morphological types of landform element that make up the landform pattern at that place. This includes placing boundaries between the elements. Then the site, or sites, can be properly located. Figure 2b shows an example of morphological types of landform element delineated in rolling low hills.

Short description of a landform element Slope class, morphological type, and a name from the glossary form the briefest description that is likely to be useful. Examples follow: Gentle crest: summit surface Gentle waxing upper slope: (no name) Precipitous maximal mid-slope: scarp Steep waning lower slope: cliff-footslope Gentle waning lower slope: footslope Very steep maximal lower slope: (no name) Very gentle open depression: drainage depression Moderate hillock: tor Level ridge: levee Very gentle flat: valley flat

26

GE

C

SUS

GE

UX

PR

MA

SCA

ST

LN

CFS

GE

LN

FOO

VS

LA

VG

V

DDE

MO

H

TOR

LE

R

LEV

VG

F

VLF

Landform

In each case, the name of the landform element type implies that other, unstated attributes have been observed or inferred. These other attributes are given below. Their values are stated in the glossary of landform elements and in the key (Table 4).

Dimensions An occurrence of a landform element extends as far as its attributes remain constant. Its dimensions, which may be much greater than the specified sample area diameter of 40 m, can be significant to land use. Terms referring to dimension appear often in the definitions of landform element types. Three dimensions are distinguished, each to be expressed in metres: Length

horizontal distance between the upper and lower margins of the element, measured down a slope line. For crests, the slope line to be used is the ridge line; for depressions, the course line (see Figure 2a). By this definition, many crests and open depressions become very long.

Width

horizontal distance between the lateral margins of the element, measured perpendicularly to the length.

Height (or depth)

difference in elevation between the upper and lower margins of the element, measured along any slope line. Height can mean different things and must be carefully defined. For crests, ridges and hillocks, define the upper margin as the point where the selected slope line coalesces with others to form the ridge line. For depressions, define the lower margin as the point where the selected slope line coalesces with others to form the course line.

Location within the landform element A site chosen to represent a landform element will often be placed centrally within it. For various reasons, a site may not be centrally placed and this should be recorded. The vertical position of the site within the height of the landform element may be the best measure: T

Top third of the height of the landform element

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Australian Soil and Land Survey Field Handbook

M

Middle third of the height of the landform element

B

Bottom third of the height of the landform element

Location within a toposequence For detailed work, the location of the site within the toposequence down a slope line may relate to landform processes. Unfortunately, slope lines, by definition, extend from a summit to the lowest point (Cayley 1859), which may be many kilometres apart. One must arbitrarily determine the effective top and bottom of the toposequence. These effective end points come where the slope line coalesces with other slope lines to form a ridge line or a course line5 (Figure 2a). In practice, ridge lines and course lines are excluded from the toposequence (see height in ‘Dimensions’, page 27). One arbitrary rule that will exclude the ridge line is to put the top of the toposequence where the contour curvature exceeds 60º in 40 m. The course line may be excluded by the same rule, or by putting the bottom of the toposequence at a stream channel. Any site can be located by its vertical and horizontal distances from the defined top and bottom of the toposequence. Drainage height (page 128) is one of these measures. The toposequence concept leads to the definition of the attributes specific catchment area and specific dispersal area (Speight 1974, 1980) that predict hillslope hydrology and erosion (see, for example, Moore et al. 1988).

Landform genesis The two following sections on geomorphological modes and agents refer to the inferred genesis of a landform element. This genesis may have spanned thousands of years. Changes, such as erosion and aggradation, produced by current land use are assessed separately as attributes of the land surface (pages 133–8). To think clearly about the origin of a landform, one should ask two questions: ‘Which agent formed it?’ and ‘What was the mode of activity of that agent?’ Landforms created by different agents, such as wind, creep and stream flow, may result from the same mode of geomorphological activity (e.g. 5

To define ridge lines and course lines by slope line coalescence, as shown in Figure 2a, departs from Cayley’s concept. He defined them as those slope lines that intersect at a knot (i.e. a pass).

28

Landform

erosion). Those created by the same agent may differ according to whether the mode of activity builds them up or breaks them down.

Mode of geomorphological activity Various modes of geomorphological activity may be distinguished (Figure 3). Gradational activity: ER

Eroded

EA

Eroded or aggraded

AG

Aggraded

Anti-gradational activity: HU

Heaved up or elevated

BU

Built up

EX

Excavated or dug out

SU

Subsided or depressed

Gradational activities are those that tend to reduce the land to a common elevation by removing material from higher places and depositing it in lower places (Chamberlin and Salisbury 1904, page 2), without necessarily reducing the angle of slope at every point. The work of streams and landslides is almost entirely in the gradational modes. However, this tendency is opposed by many processes that commonly act in an anti-gradational mode. These modes are characteristic of volcanism, diastrophism and various kinds of human and biological activity. However, many engineering works involve erosion and aggradation because these gradational modes use less energy than anti-gradational modes. For the same reason, erosion and aggradation may easily be induced unintentionally by land use (pages 133–8). To judge the mode of geomorphological activity responsible for a given landform element, the observer must visualise a former surface that has suffered distortion, burial or removal of material, and seek evidence that such activity has taken place. (Information on soil and substrate materials relevant to this investigation should be recorded as specified in other sections.) Allow for the recording of more than one mode of activity, together with options concerning geomorphological agents.

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Australian Soil and Land Survey Field Handbook

ERODED

ERODED or AGGRADED

AGGRADED

GRADATIONAL

HEAVED UP or ELEVATED

BUILT UP

EXCAVATED or DUG OUT

SUBSIDED or DEPRESSED

ANTIGRADATIONAL

Figure 3 Modes of geomorphological activity.

Geomorphological agent Geomorphological agents that help produce distinctive landform elements are listed in Table 3. Much of the standard terminology relevant to landform elements presumes that the geomorphological agent responsible for a landform is known; this presumption is incorporated explicitly in the following glossary ‘Landform element key and glossary’. In practice, the observer may find it difficult to infer the agent responsible for producing a given landform element correctly. The problem may be compounded by the apparent significance of more than one agent. In such cases, the observer should record both (a) the dominant agent, or the agent that is confidently inferred; and (b) a subordinate agent, or an agent that is dubiously inferred. In dubious cases, leave category (a) blank. The importance of identifying landform elements with the agent channelled stream flow is discussed under ‘Channel depth relative to width’ on page 49.

Underlying materials While inferences about geomorphological agents and their mode of activity are essential to define many types of landform element (and landform pattern), observations of the underlying materials are not. Since these materials are often inaccessible to the observer, they should not be definitive for landforms. Landforms are seen as indicators of the underlying materials, permitting their

30

Landform

Table 3 Geomorphological agents significant for definition of landform elements and landform patterns Gravity GR

Collapse, or particle fall Precipitation

SO SM WM SH

Solution Soil moisture status changes; creep Water-aided mass movements; landslides Sheet flow, sheet wash, surface wash Stream flow

OV CH

Overbank stream flow, unchannelled Channelled stream flow Wind

WI

Wind Ice

FR GL

Frost, including freeze–thaw Glacier flow Standing water

WA TI EU

Waves Tides Eustasy; changes in sea level Internal forces

DI VO

Diastrophism; earth movements Volcanism Biological agents

BI HU

Non-human biological agents; coral Human agents Extraterrestrial agents

IM

Impact by meteors

extrapolation from limited exposures. The description of bedrock and regolith is discussed in the chapter ‘Substrate’ on page 205.

LANDFORM ELEMENT KEY AND GLOSSARY The glossary below aims to provide an adequate, concise set of names for types of landform element. Where different landform elements in a survey

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Australian Soil and Land Survey Field Handbook

area have the same type name, distinguish them by qualifying terms based on attributes of landform element or of land surface. Examples are: s steep maximal upper hillslope s rocky, gentle upper hillslope s severely gullied footslope. Each glossary definition is based on the attributes that have been listed. Table 4 is a key for finding the name of a landform element, the attributes of which have been evaluated. Attribute values that have not been observed but merely inferred from a glossary definition must not be treated as data.

Glossary ALC

Alcove

moderately inclined to very steep, short open depression with concave cross-section, eroded by collapse, landslides, creep or surface wash.

BKP

Backplain

large flat resulting from aggradation by overbank stream flow at some distance from the stream channel and in some cases biological (peat) accumulation; often characterised by a high watertable and the presence of swamps or lakes; part of a covered plain landform pattern.

BAN

Bank (stream bank)

very short, very wide slope, moderately inclined to precipitous, forming the marginal upper parts of a stream channel and resulting from erosion or aggradation by channelled stream flow.

BAR

Bar elongated, gently to moderately inclined, low ridge (stream bar) built up by channelled stream flow; part of a stream bed.

DUB

Barchan dune

crescent-shaped dune with tips extending leeward (downwind), making this side concave and the windward (upwind) side convex. Barchan dunes tend to be arranged in chains extending in the dominant wind direction.

BEA

Beach

short, low, very wide slope, gently or moderately inclined, built up or eroded by waves, forming the shore of a lake or sea. 32

Landform

BRI

Beach ridge very long, nearly straight, low ridge, built up by waves and usually modified by wind. A beach ridge is often a relict feature remote from the beach.

BEN

Bench

short, gently or very gently inclined minimal mid-slope element eroded or aggraded by any agent.

BER

Berm

(i) short, very gently inclined to level minimal mid-slope in an embankment or cut face, eroded or aggraded by human activity. (ii) flat built up by waves above a beach.

BOU

Blow-out

usually small, open or closed depression excavated by the wind.

BRK

Breakaway

steep maximal mid-slope or upper slope, generally comprising both a very short scarp (free face) that is often bare rockland, and a stony scarp-footslope (debris slope); often standing above a pediment.

Channel

see Stream channel.

CBE

Channel bench

flat at the margin of a stream channel aggraded and partly eroded by overbank and channelled stream flow; an incipient flood plain. Channel benches have been referred to as ‘low terraces’, but the term ‘terrace’ should be restricted to landform patterns above the influence of active stream flow.

CIR

Cirque

precipitous to gently inclined, typically closed depression of concave contour and profile excavated by ice. The closed part of the depression may be shallow, the larger part being an open depression like an alcove.

CLI

Cliff

very wide, cliffed (greater than 72º) maximal slope usually eroded by gravitational fall as a result of erosion of the base by various agencies; sometimes built up by marine organisms (cf. Scarp).

CFS

Clifffootslope

slope situated below a cliff, with its contours generally parallel to the line of the cliff, eroded by sheet wash or 33

34 Eroded

S, U, M, L

Slope (unspecified: upper, mid-slope, lower, or simple)

Collapse, landslide or sheet wash

Collapse

Wind or waves People

Channel or overbank flow Wind Wind

Precipitous, very wide, maximal

(see also Hillock) From adjacent beach From adjacent playa From beach; relict (see also Slope) To enclose a depression Cliffed, very wide, maximal

Relict bar Relict levee etc.

(see also Ridge) Weakly oriented Crescentic Parabolic Longitudinal

Scarp

Cliff

SCA

CLI

DUN FOR LUN BRI EMB DAM

Dunea Foredune Lunette Beach ridge Embankment a Dam

Built up or eroded

R

Ridge

CON MOU LEV BAR SCR PST

Volcanism Wind

Heaved up Built up or eroded

H

Hillock

Volcanism People Overbank flow Channel flow

SUS REC DUC TOR RER TUM DUN DUH DUB DUP DUF Summit surface Risecrest Dunecrest Tor Residual rise Tumulus Dunea Hummocky dune Barchan dune Parabolic dune Linear or longitudinal (seif) dune Cone (volcanic) Mound Levee Bar (stream) Scroll Prior stream

Wind Wind Creep or sheet wash

Eroded Built up or eroded Eroded With bare rock Regolith-covered

HCR

C

Code

Name Hillcrest

Not very wide, steeper Very wide, gentler Not very wide, gentler

Creep or sheet wash

Landform element type

Eroded

Other discriminators

Code

Land-forming agent

Crest

Mode of activity

Name

Morphological type

Table 4 Key to landform element types

Australian Soil and Land Survey Field Handbook

35 F

Flat

Sheet wash Sheet wash, landslide or creep Collapse

Eroded or aggraded

Aggraded

Any agent Sheet wash Waves

Any mode Eroded

Eroded

Any agent People Landslide or sheet wash Creep or sheet wash

Landslide or sheet wash Creep or sheet wash

People Channel flow Waves Wind Creep or sheet wash Collapse, landslide or sheet wash

Sheet wash, creep or landslide People Landslide

Land-forming agent

Eroded or aggraded

Eroded

Eroded and aggraded Built up Eroded or aggraded Built up or eroded

Mode of activity

a Landform element type name occurs more than once.

L

M

Mid-slope

Lower slope

S

Code

Simple slope

Slope (unspecified) (cont.)

Name

Morphological type

Minimal slope Small scarp and scarp-footslope together At foot of a cliff (see also Lower slope) At foot of a scarp (see also Lower slope) Minimal slope Minimal slope At foot of a cliff (see also Mid-slope) At foot of a scarp (see also Mid-slope) Large, gentle, mainly eroded (see also Flat) Waning slope, not large Rock fragments Mainly formed by erosion; aggradation is local Large, gentle, mainly eroded (see also Flat) Rock Rock

Very wide

(see also Ridge)

Hummocky

Other discriminators

Rock flat Rock platform

Plain

Talus Cliff-footslopea

Footslope

RFL RPL

PLA

TAL CFS

FOO

PED

Pedimenta

SFS

Scarp-footslopea

SFS

CFS

Cliff-footslopea

Scarp-footslopea

EMB BAN BEA DUS RES BRK

Embankmenta Bank (stream) Beach Duneslope Riseslope Breakaway

BEN BER CFS

CUT LDS

Cut face Landslide

Bench Berm (i) Cliff-footslopea

HSL

Code

Hillslope

Name

Landform element type

Landform

36

Open depression

V

Eroded or aggraded Eroded, aggraded, dug out or built up

Eroded

Built up

Aggraded

Eroded or aggraded

Sheet wash Channel flow

People Waves Coral Landslide, creep or surface wash Channel flow and collapse Glacier flow

Tides

Overbank flow Channel flow Channel or overbank flow

Channel or overbank flow

Channel flow

Eroded or dug out Eroded or aggraded

Mainly eroded; part of stream channel

Stream bed

STB

DDE STC

CIR

Cirquea Part dug out and closed depression Gentle or flat, long

Drainage depression Stream channel

GUL

TEP TDF ITF STF FIL BER REF ALC Terrace plain Tidal flat Intertidal flat Supratidal flat Fill-top Berm (ii) Reef flat Alcove Gully

BKP SRP FLD

TEF CBE Terrace flat Channel bench Backplain Scroll plain Flood-out

VLF

FAN

Valley flat

Fan

COS SCD PED

Code

With precipitous walls

Sloping, short

Above a beach

Soil-eroded, small Large, gentle, unidirectional, mainly eroded (see also Lower slope) Radial, mainly aggraded Enclosed by slopes, mainly aggraded Relict, small At channel margin, small Large Large Radial, on a flood plain Relict, large Undifferentiated Frequently inundated Seldom inundated

Cut-over surface Scald Pedimenta

People Wind or sheet wash Sheet wash

Name

Landform element type

F

Other discriminators

Code

Land-forming agent

Flat (cont.)

Mode of activity

Name

Morphological type

Table 4 (cont.)

Australian Soil and Land Survey Field Handbook

37

D

Code

Dug out

Aggraded

Volcanism Volcanism, meteor or people People

Wind Glacier flow

Wind Solution Collapse Channel flow Waves or coral Overbank flow or peat

Channel flow Wind or waves People Any agent

Built up or dug out Dug out Any mode

Eroded

Overbank flow (etc.)

Channel flow and tides

Land-forming agent

Aggraded

Mode of activity

a Landform element type name occurs more than once.

Closed depression

Open depression (cont.)

Name

Morphological type

Long, curved Large, saltwater-filled Surface watertable (see also Open depression) Small Partly eroded open depression Usually water-filled By explosion

Large, water-filled Large, usually dried up

Tapered; tide water only Tapered; river and tide water Flat; surface watertable (see also Closed depression) Between scrolls Between ridges

Other discriminators

SWP

Swampa

MAA CRA PIT Pit

BOU CIR

DBA DOL DOC OXB LAG SWP

Maar Crater

Blow-out Cirquea

Deflation basin Solution doline Collapse doline Ox-bow Lagoon Swampa

SWL SWL TRE LAK PLY

EST

Estuary

Swale (ii) Swale (i) Trench Lake Playa

TDC

Code

Tidal creek

Name

Landform element type

Landform

Australian Soil and Land Survey Field Handbook

water-aided mass movement, and aggraded locally by collapsed material from above. DOC

Collapse doline

steep-sided, circular or elliptical closed depression, commonly funnel-shaped, characterised by subsurface drainage and formed by collapse of underlying caves within bedrock.

CON

Cone (volcanic)

hillock with a circular symmetry built up by volcanism. The crest may form a ring around a crater.

CRA

Crater

steep to precipitous closed depression excavated by explosions due to volcanism, human action, or impact of an extraterrestrial object.

CUT

Cut face

slope eroded by human activity.

COS

Cut-over surface

flat eroded by human activity.

DAM

Dam

ridge built up by human activity so as to close a depression.

DBA

Deflation basin

basin excavated by wind erosion which removes loose material, commonly above a resistant or wet layer.

DDE

Drainage depression

level to gently inclined, long, narrow, shallow open depression with smoothly concave cross-section, rising to moderately inclined side slopes, eroded or aggraded by sheet wash.

DUN

Dune

moderately inclined to very steep ridge or hillock built up by the wind. This element may comprise dunecrest and duneslope.

DUC

Dunecrest

crest built up or eroded by the wind (see Dune).

DUS

Duneslope

slope built up or eroded by the wind (see Dune).

EMB

Embankment

ridge or slope built up by human activity.

38

Landform

EST

Estuary

stream channel close to its junction with a sea or lake, where the action of channelled stream flow is modified by tide and waves. The width typically increases downstream.

FAN

Fan

large, gently inclined to level element with radial slope lines inclined away from a point, resulting from aggradation, or occasionally from erosion, by channelled, often braided, stream flow, or possibly by sheet flow.

FIL

Fill-top

flat aggraded by human activity.

FLD

Flood-out

flat inclined radially away from a point on the margin or at the end of a stream channel, aggraded by overbank stream flow, or by channelled stream flow associated with channels developed within the overbank flow; part of a covered plain landform pattern.

FOO

Footslope

moderately to very gently inclined waning lower slope resulting from aggradation or erosion by sheet flow, earth flow or creep (cf. Pediment).

FOR

Foredune

very long, nearly straight, moderately inclined to very steep ridge built up by the wind from material from an adjacent beach.

GUL

Gully

open depression with short, precipitous walls and moderately inclined to very gently inclined floor or small stream channel, eroded by channelled stream flow and consequent collapse and water-aided mass movement.

HCR

Hillcrest

very gently inclined to steep crest, smoothly convex, eroded mainly by creep and sheet wash. A typical element of mountains, hills, low hills and rises.

HSL

Hillslope

gently inclined to precipitous slope, commonly simple and maximal, eroded by sheet wash, creep or wateraided mass movement. A typical element of mountains, hills, low hills and rises.

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Australian Soil and Land Survey Field Handbook

DUH

Hummocky very gently to moderately inclined rises or hillocks (weakly built up or eroded by wind and lacking distinct oriented) orientation or regular pattern. dune

ITF

Intertidal flat

see Tidal flat.

LAG

Lagoon

closed depression filled with water that is typically salt or brackish, bounded at least in part by forms aggraded or built up by waves or reef-building organisms.

LAK

Lake

large, water-filled closed depression.

LDS

Landslide

moderately inclined to very steep slope, eroded in the upper part and aggraded in the lower part by wateraided mass movement, characterised by irregular hummocks.

LEV

Levee

very long, low, narrow, nearly level, sinuous ridge immediately adjacent to a stream channel, built up by overbank flow. Levees are built, usually in pairs bounding the two sides of a stream channel, at the level reached by frequent floods. This element is part of a covered plain landform pattern. For an artificial levee, use Embankment. See also Prior stream.

DUF

Linear or large, sharp-crested, elongated, longitudinal (linear) longitudinal dune or chain of sand dunes, oriented parallel, rather (seif) dune than transverse (perpendicular), to the prevailing wind. (Not to be confused with the trailing arms of parabolic dunes.)

LUN

Lunette

elongated, gently curved, low ridge built up by wind on the margin of a playa, typically with a moderate, wavemodified slope towards the playa and a gentle outer slope.

MAA

Maar

level-floored, commonly water-filled closed depression with a nearly circular, steep rim, excavated by volcanism.

40

Landform

MOU

Mound

hillock built up by human activity.

OXB

Ox-bow

long, curved, commonly water-filled closed depression eroded by channelled stream flow but closed as a result of aggradation by channelled or overbank stream flow during the formation of a meander plain landform pattern. The floor of an ox-bow may be more or less aggraded by overbank stream flow, wind, and biological (peat) accumulation.

Pan

see Playa.

DUP

Parabolic dune

sand dune with a long, scoop-shaped form, convex in the downwind direction so that its horns point upwind, whose ground plan approximates the form of a parabola. The dunes left behind can be referred to as trailing arms. Where many such dunes have traversed an area, these can give the appearance of linear dunes.

PED

Pediment

large, gently inclined to level (<1%) waning lower slope, with slope lines inclined in a single direction, or somewhat convergent or divergent, eroded or sometimes slightly aggraded by sheet flow (cf. Footslope). It is underlain by bedrock.

PIT

Pit

closed depression excavated by human activity.

PLA

Plain

large, very gently inclined or level element, of unspecified geomorphological agent or mode of activity.

PLY

Playa

large, shallow, level-floored closed depression, intermittently water-filled, but mainly dry due to evaporation, bounded as a rule by flats aggraded by sheet flow and channelled stream flow.

PST

Prior stream

long, generally sinuous, low ridge built up from materials originally deposited by stream flow along the line of a former stream channel. The landform element may include a depression marking the old stream bed, and relict levees.

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Australian Soil and Land Survey Field Handbook

REF

Reef flat

flat built up to sea level by marine organisms.

RER

Residual rise

hillock of very low to extremely low relief (<30 m) and very gentle to steep slopes. This term is used to refer to an isolated rise surrounded by other landforms.

REC

Risecrest

crest of hillock of very low to extremely low relief (<30 m) (see Residual rise).

RES

Riseslope

slope of hillock of very low to extremely low relief (<30 m) (see Residual rise).

RFL

Rock flat

flat of bare consolidated rock, usually eroded by sheet wash.

RPL

Rock platform

flat of consolidated rock eroded by waves.

SCD

Scald

flat, bare of vegetation, from which soil has been eroded or excavated by surface wash or wind.

SCA

Scarp

very wide, steep to precipitous maximal slope eroded by gravity, water-aided mass movement or sheet flow (cf. Cliff).

SFS

Scarpfootslope

waning or minimal slope situated below a scarp, with its contours generally parallel to the line of the scarp.

SCR

Scroll

long, curved, very low ridge built up by channelled stream flow and left relict by channel migration. Part of a meander plain landform pattern.

SRP

Scroll plain large flat resulting from aggradation by channelled stream flow as a stream migrates from side to side; the dominant element of a meander plain landform pattern. This landform element may include occurrences of scroll, swale and ox-bow.

DOL

Solution doline

steep-sided, circular or elliptical closed depression, commonly funnel-shaped, characterised by subsurface

42

Landform

drainage and formed by dissolution of the surface or underlying bedrock. STB

Stream bed linear, generally sinuous open depression forming the bottom of a stream channel, eroded and locally excavated, aggraded or built up by channelled stream flow. Parts that are built up include bars.

STC

Stream channel

linear, generally sinuous open depression, in parts eroded, excavated, built up and aggraded by channelled stream flow. This element comprises stream bed and banks.

SUS

Summit surface

very wide, level to gently inclined crest with abrupt margins, commonly eroded by water-aided mass movement or sheet wash.

STF

Supratidal flat

see Tidal flat.

SWL

Swale

(i) linear, level-floored open depression excavated by wind, or left relict between ridges built up by wind or waves, or built up to a lesser height than them. (ii) long, curved open or closed depression left relict between scrolls built up by channelled stream flow.

SWP

Swamp

almost level, closed or almost closed depression with a seasonal or permanent watertable at or above the surface, commonly aggraded by overbank stream flow and sometimes biological (peat) accumulation.

TAL

Talus

moderately inclined or steep waning lower slope, consisting of rock fragments aggraded by gravity.

TEF

Terrace flat

small flat aggraded or eroded by channelled or overbank stream flow, standing above a scarp and no longer frequently inundated; a former valley flat or part of a former flood plain.

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Australian Soil and Land Survey Field Handbook

TEP

Terrace plain

large or very large flat aggraded by channelled or overbank stream flow, standing above a scarp and no longer frequently inundated; part of a former flood plain.

TDC

Tidal creek

intermittently water-filled open depression in parts eroded, excavated, built up and aggraded by channelled tide-water flow; type of stream channel characterised by a rapid increase in width downstream.

TDF

Tidal flat

large flat subject to inundation by water that is usually salt or brackish, aggraded by tides. An intertidal flat (ITF) is frequently inundated; a supratidal flat (STF) is seldom inundated.

TOR

Tor

steep to precipitous hillock, typically convex, with a surface mainly of bare rock, either coherent or comprising subangular to rounded, large boulders (exhumed core-stones, also themselves called tors) separated by open fissures; eroded by sheet wash or water-aided mass movement.

TRE

Trench

open depression excavated by human activity.

TUM

Tumulus

hillock heaved up by volcanism (or, elsewhere, built up by human activity at a burial site).

VLF

Valley flat

small, gently inclined to level flat, aggraded or sometimes eroded by channelled or overbank stream flow, typically enclosed by hillslopes; a miniature alluvial plain landform pattern.

DESCRIPTION OF LANDFORM PATTERN The significant kinds of landform pattern in Australia may be described and differentiated by the following attributes assessed within a circle of about 300 m radius: s s s s

relief modal slope stream channel occurrence mode of geomorphological activity 44

Landform

s geomorphological agent s status of geomorphological activity s component landform elements. The glossary that follows (‘Landform pattern glossary’, page 55) is based explicitly on these attributes. Many other attributes may be observed, particularly by means of air photos (Speight 1977), thereby permitting finer discrimination between landform patterns. Landform pattern description is seldom built up from field observations alone, so that this section is marginal to the purpose of the Handbook. It aims rather to provide a secure broader geomorphological context for field work. In the field, the observer should take care not to include parts of adjacent dissimilar landform patterns and thereby compromise the description of the landform pattern in which the observation point is found. Landform pattern boundaries, such as hillslope–flood plain junctions or dissection heads, may be recorded by a diagram.

Relief Relief is defined as the difference in elevation between the high and low points of a land surface. Its estimation is made easier by visualising two surfaces of accordance that are planar or gently curved, one touching the major crests of a landform pattern, and the other passing through the major depressions. The average vertical separation of the two surfaces is a measure of the relief. Make this estimation at a field site, either visually or by using a map, and express it in metres. Relief is the definitive characteristic for the terms mountains, hills, low hills, rises and plains when used as types of erosional landform pattern (Table 5). The class boundaries, shown in Tables 5 and 6, are set at 300 m, 90 m, 30 m and 9 m. These class limits and the class names are similar to those used by Löffler (1974), and are broadly compatible with those of Löffler and Ruxton (1969). Table 6 lists types of landform pattern defined in the ‘Landform pattern glossary’ according to their typical relief class. Those types for which the relief class is definitive are in italics.

Modal slope Modal slope is defined as the most common class of slope occurring in a landform pattern. Where slope classes have been obtained by systematic sampling, define the classes using equal increments on a scale of the logarithm 45

Australian Soil and Land Survey Field Handbook

of the slope tangent, a procedure intended to normalise frequency distributions of observed slope (Speight 1971). Where the most common slope class is estimated by direct observation, the estimate can be compared with the calculated value by using the log–normal model. Modal slope class determines the use of certain adjectives applied to landform patterns that are characterised by alternating crests and depressions. These are: rolling for moderate modal slopes (10–32%); undulating for gentle slopes (3–10%); and gently undulating for very gentle slopes (1–3%) (cf. Soil Survey Staff 1951, pages 161–5). The other slope classes, precipitous, very steep, steep and level, are to be applied as they stand. The terminology for simple erosional landform patterns based on relief and modal slope is given in Table 5. Table 5 defines the category badlands by various combinations of high slope values and low relief values. These combinations imply extremely close spacing of streams or valleys. Specifically, if one assumes a sawtooth terrain profile, the valley spacing implied is less than 100 m in areas with 50 m relief and less than 30 m in areas with 5 m relief; these values appear to accord with usage. Table 7 lists types of landform pattern in order of their typical class of modal slope. This table should not be regarded as definitive, because slope within each type of landform pattern may vary widely.

Short description of a landform pattern The categories of relief and modal slope class given by the code letters in the margins of Table 5, added to a name from the ‘Landform pattern glossary’, form the briefest description of landform patterns that is likely to be useful. Named landform pattern types are discriminated by many other attributes, some of which are given below. Type names must be used with great care. In the ‘Landform pattern glossary’, cross-references are given to the similar landform pattern types with which a given type could be confused.

Stream channel occurrence Several attributes that describe the occurrence and pattern of surface stream channels have diagnostic value. Use of the following attributes may clarify the observable differences between landform patterns, particularly in plains where mapping criteria are elusive. When assessing attributes of stream channel occurrence, it is easy to make errors by not setting limits to the area to be described. Tentative landform pattern boundaries must be drawn to clarify these limits. Major stream

46

Very high >300 m (~ 500 m)

High 90–300 m (~ 150 m)

Low 30–90 m (~ 50 m)

Very low 9–30 m (~ 15 m)

Extremely low <9 m (~ 5 m)

M

H

L

R

P

Relief

47 LP Level plain

—

—

—

GP Gently undulating plain

GR Gently undulating rises

—

—

UP Undulating plain

UR Undulating rises

UL Undulating low hills

UH Undulating hills

—

Level <1% (~ 1:300) —

Gently inclined 3–10% (~ 6%)

Very gently inclined 1–3% (~ 2%)

—

GE

VG

LE

RP Rolling plain

RR Rolling rises

RL Rolling low hills

RH Rolling hills

RM Rolling mountains

Moderately inclined 10–32% (~ 20%)

MO

Modal terrain slope

B Badlands

SR Steep rises

SL Steep low hills

SH Steep hills

SM Steep mountains

Steep 32–56% (~ 40%)

ST

Table 5 Simple types of erosional landform pattern characterised by relief and modal slope

B Badlands

B Badlands

VL Very steep low hills

VH Very steep hills

VM Very steep mountains

Very steep 56–100% (~ 70%)

VS

B Badlands

B Badlands

B Badlands

PH Precipitous hills

PM Precipitous mountains

Precipitous >100% (~ 150%)

PR

Landform

Australian Soil and Land Survey Field Handbook

Table 6 Landform pattern types ordered by typical relief class (those types for which the relief class is definitive are in italics) Typical relief

Landform pattern types

Very high >300 m

Mountains, volcano

High 90–300 m

Hills, volcano, caldera, meteor crater

Low 30–90 m

Low hills, volcano, caldera, meteor crater

Very low 9–30 m

Rises, terrace, dunefield, lava plain, coral reef, peneplain, karst

Extremely low <9 m

Plain, pediment, pediplain, sheet-flood fan, alluvial fan, alluvial plain, flood plain, meander plain, bar plain, covered plain, anastomotic plain, stagnant alluvial plain, delta, playa plain, tidal flat, beach ridge plain, chenier plain, sand plain, made land

channels are best mapped as wholly within one landform pattern or another, rather than marking a boundary.

Stream channel spacing The average spacing of stream channels, L/N, is determined by counting the number, N, of their intersections with an arbitrary line of length L.6 A convenient tool for estimating channel spacing is a circle, with a circumference of 2 km at map or photo scale, drawn on transparent material. Suitable classes for stream channel spacing, based on existing data, are: AB SP VW WS MS CS VC NU

6

Absent or very rare Sparse Very widely spaced Widely spaced Moderately spaced Closely spaced

>2500 m 1585–2500 m 1000–1585 m 625–1000 m 400–625 m 250–400 m

Very closely spaced Numerous

158–250 m <158 m

The average spacing, L/N, is the reciprocal of stream channel frequency, N/L (Speight 1977), a measure advocated by McCoy (1971) to replace the less convenient drainage density, Dd (Horton 1945). Mark (1974) has demonstrated a logical and empirical relationship from which it follows that stream channel spacing is related to drainage density by: L/N = 1.571/Dd

48

Landform

Table 7 Landform pattern types ordered by typical modal slope class Typical modal slope class

Landform pattern types

Precipitous >100%

(Rare in Australia)

Very steep 56–100%

Mountains, escarpment, volcano, caldera

Steep 32–56%

Hills

Moderately inclined 10–32%

Low hills, karst, meteor crater

Gently inclined 3–10%

Rises, beach ridge plain, dunefield, lava plain, coral reef

Very gently inclined 1–3%

Pediments, alluvial fan, sand plain

Level <1%

Plains, sheet-flood fan, pediplain, peneplain, alluvial plain, flood plain, meander plain, bar plain, covered plain, anastomotic plain, stagnant alluvial plain, terrace, tidal flat, made land, playa plain

Stream channel development The degree of development of stream channels may be categorised as follows: O I

Absent Incipient

no traces of channelled flow can be detected. traces of channelled flow are very shallow, narrow and discontinuous.

E

Erosional

A

Alluvial

continuous linear channels occur; their width and depth are considerable and display somewhat constant values suited to the available flow. Flood plains are not formed. continuous linear channels occur, with rather large width and depth; they are essentially constant with downstream distance and are suited to the available flow. Flood plains of vertical or lateral accretion are formed.

Channel depth relative to width Channel depth and width refer to the dimensions of a landform that is dominated by channelled stream flow. The limit of channelled stream flow dominance must be identified before width or depth can be estimated. Depth is taken from the top of the stream bank down to the average height of the line following the deepest part of the channel.

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Australian Soil and Land Survey Field Handbook

The distinction between stream bank and hillslope or scarp according to dominant process requires particular care where streams are incised, especially if they are cut into terraces that could be mistaken for flood plains. For detailed studies, keep records of width and depth measurements. In other surveys, use the following classes of relative depth. D M S V

Deep Moderately deep Shallow Very shallow

width/depth ratio <20:1 width/depth ratio 20:1 to 50:1 width/depth ratio 50:1 to 150:1 width/depth ratio >150:1

Stream channel migration The presence of relict channel landforms or unvegetated, newly formed or immovable channel margins may permit an assessment of channel migration as: R S F

Rapidly migrating Slowly migrating Fixed

Stream-wise channel pattern In a traverse downstream, it may happen that tributaries enter the stream at frequent intervals, or that the stream splits into distributaries, or that these tendencies are absent (the non-tributary case) or are in balance with each other (the braided or anastomotic case, called here reticulated) giving four classes of stream-wise channel pattern (Figure 4a): T

D

Tributary Non-tributary Distributary

R

Reticulated

N

Channel network integration In an integrated channel network, one can traverse from any point on a stream channel to any other point on a stream channel without passing through any 50

Landform

(a) Stream-wise channel patterns

TRIBUTARY

NON-TRIBUTARY

DISTRIBUTARY

RETICULATED

(b) Integration of channel network

INTEGRATED

INTERRUPTED

DISINTEGRATED

(c) Channel network directionality

CENTRIFUGAL

DIVERGENT

UNIDIRECTIONAL

CENTRIPETAL

CONVERGENT

NON-DIRECTIONAL

Figure 4 Stream channel pattern attributes.

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Australian Soil and Land Survey Field Handbook

landform elements other than stream channels. The channel network may be interrupted at points where water loss into the ground or the atmosphere is sufficiently large, and in the extreme case, typical of karst terrain, the surface stream network is disintegrated. Classes of channel network integration (Figure 4b) are: I P D

Integrated Interrupted (partial integration) Disintegrated

Channel network directionality This attribute combines two simpler attributes: the degree of lineation, that is, the degree to which the channels tend to align in an organised way; and the degree of convergence or divergence of channels downstream (Figure 4c). The latter is distinct from tributary/distributary behaviour, which refers to the combining and splitting of stream channels, rather than their directionality. Proposed classes are: F D U C P B N

Centrifugal Divergent Unidirectional Convergent Centripetal Bidirectional Non-directional

maximum divergence >90º maximum divergence between 10º and 90º convergence or divergence <10º maximum convergence between 10º and 90º maximum convergence >90º two lineations (e.g. ‘trellis’) no significant orientation, convergence or divergence

To illustrate the significance of stream channel occurrence in discriminating between landform patterns, Table 8 presents examples of landform pattern types ordered according to each of these seven attributes.

Mode of geomorphological activity The modes of geomorphological activity are those considered in the description of landform elements (see Figure 3, page 30). Table 9 indicates the dominant mode of geomorphological activity in common types of landform pattern.

Geomorphological agent Landform patterns are subject to the same geomorphological agents as are landform elements (see Table 3, page 31). The problems of assigning agents 52

Landform

Table 8 Examples of types of landform pattern ordered according to attributes of stream channel occurrence Attributes of stream channel occurrence

Examples of landform pattern types

Stream channel spacing Absent or very rare Sparse Very widely spaced Widely spaced Moderately spaced Closely spaced Very closely spaced Numerous

Sand plain, beach ridge plain Made land Very steep mountains Meander plain, steep hills Anastomotic plain, undulating rises Steep low hills Precipitous hills Badlands, bar plain, pediment

Stream channel development Absent Incipient Erosional Alluvial

Dunefield, pediplain, playa plain Pediment, sheet-flood fan Mountains, hills, rises Meander plain, bar plain, covered plain

Stream channel depth relative to width Deep Moderately deep Shallow Very shallow

Covered plain, anastomotic plain Meander plain Bar plain Pediment

Stream channel migration Rapidly migrating Slowly migrating Fixed

Bar plain, meander plain Covered plain Mountains, hills, rises

Stream-wise channel pattern Tributary Non-tributary Distributary Reticulated

Mountains, hills, rises Meander plain, covered plain Delta, sheet-flood fan, pediment Bar plain, anastomotic plain

Stream channel network integration Integrated Interrupted (partial integration) Disintegrated

Mountains, hills, rises Volcano Karst

Stream channel network directionality Centrifugal Divergent Unidirectional Convergent Centripetal Non-directional

Volcano Pediment, sheet-flood fan Meander plain, bar plain, covered plain Hills, rises Caldera Mountains, hills, rises

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Australian Soil and Land Survey Field Handbook

Table 9 Landform pattern types grouped according to the dominant mode of geomorphological activity Dominant mode of geomorphological activity

Landform pattern types

Gradational ER

Eroded

Mountains, hills, rises, karst, pediplain, peneplain

EA

Eroded or aggraded

Pediment, made land

AG

Aggraded

Alluvial plain, flood plain, alluvial fan, bar plain, meander plain, covered plain, terrace, sheet-flood fan, lava plain, playa plain, tidal flat

Anti-gradational HU

Heaved up

Marine plain

BU

Built up

Volcano, coral reef, dunefield, beach ridge plain

EX

Excavated

Caldera, meteor crater

SU

Subsided

(Rare in Australia)

and of expressing the relative significance of more than one agent for a landform pattern are even more acute than for landform elements. Make provision for listing dominant, co-dominant and accessory geomorphological agents. Table 10 shows the incidence of geomorphological agents in types of landform pattern. Landform patterns, being larger than landform elements, commonly have longer histories. The landform pattern description often identifies longer acting or relict geomorphological modes and agents.

Status of geomorphological activity It is important for theoretical and practical purposes to distinguish, if possible, between landform patterns in which the formative geomorphological processes continue at the present time, and those in which they are no longer active, the landform features being relict. The problem in assigning activity status is that many processes are episodic, so that the observation of no activity may mean that an episodic process is in a quiescent phase. The following scale does not distinguish between processes that operate continuously but extremely slowly and those episodic processes that are very rare:

54

Landform

C F S B R U

Continuously active Frequently active Seldom active Barely active to inactive Relict Unspecified

Table 11 shows how types of landform pattern vary in their status of geomorphological activity. Note that flood plains, including bar plains, meander plains, covered plains, anastomotic plains, and deltas, are distinguished from terraces or stagnant alluvial plains by having frequently active rather than seldom active or inactive stream flow. This may have legal significance. The frequency of occurrence of inundation (see page 138) that is classed as frequently active in this Handbook is an Average Recurrence Interval of 50 years or less. A landform pattern may change from one type to another type if the status of geomorphological activity changes for any reason, including human interference (e.g. diverting a stream or building a dam).

Component landform elements Certain kinds of landform element are typical of a given landform pattern. Some are found commonly and others occasionally in a given type. These landform elements are listed for each type of landform pattern in the ‘Landform pattern glossary’.

LANDFORM PATTERN GLOSSARY The definitions in this glossary refer explicitly to the attributes of landform patterns that have been set down in the preceding sections. Consequently, they differ from the original definitions by the cited authors. Cross-references and the tables in this section should be used to distinguish between landform pattern types that are similar. Alluvial fan, sheet-flood fan and pediment are particularly difficult to distinguish. They differ mainly in that stream channels are better developed and deeper on

55

Soil moisture status changes; creep

Water-aided mass movements; landslides

Sheet flow, sheet wash, surface wash

SM

WM

SH

56

Channelled stream flow

Wind

CH

WI

Frost, including freeze–thaw

Glacier flow

FR

GL

Ice

Overbank stream flow, unchannelled

OV

Stream flow

Solution

Precipitation

Gravity: collapse, or particle fall

SO

GR

Geomorphological agent

(Rare in Australia)

(Rare in Australia)

Dunefield

Meander plain, bar plain

Covered plain, anastomotic plain

Hills etc., sheet-flood fan, pediment, pediplain, peneplain

Karst

(Rare in Australia)

Dominant agent

Playa plain, beach ridge plain

Flood plain, alluvial plain, terrace

Flood plain, alluvial plain, terrace

Playa plain

Hills etc.

Hills etc.

Co-dominant agent

Landform patterns

Table 10 Incidence of geomorphological agents in types of landform pattern

Hills etc.

Beach ridge plain, pediment

Karst

Playa plain

Hills etc., karst, volcano, dunefield, meteor crater

Accessory agent

Australian Soil and Land Survey Field Handbook

Eustasy: changes in sea level

EU

Volcanism

VO

57

IM

Human agents

HU

Impact by meteors

Extraterrestrial agents

Non-human biological agents; coral

BI

Biological agents

Diastrophism: earth movements

DI

Meteor crater

Made land

Coral reef

Volcano, caldera, lava plain

(Rare in Australia)

(Rare in Australia)

Tides

TI

Internal forces

Tidal flat

Waves

Lacustrine plain

Dominant agent

WA

Standing water

Geomorphological agent

Landform patterns

Beach ridge plain, playa plain

Co-dominant agent

Beach ridge plain

Tidal flat

Accessory agent

Landform

Australian Soil and Land Survey Field Handbook

Table 11 Typical activity status of the dominant geomorphological agent in types of landform pattern Typical activity status

Landform patterns

Continuously active

Mountains, hills, rises, karst, coral reef

Frequently active

Pediment, sheet-flood fan, flood plain, bar plain, meander plain, covered plain, anastomotic plain, alluvial fan, tidal flat, dunefield, playa plain

Seldom active

Volcano, (lower) terrace

Barely active to inactive

Pediplain, peneplain, stagnant alluvial plain

Relict

Caldera, meteor crater, (higher) terrace, beach ridge plain, lava plain, made land

Unspecified

Plain, alluvial plain

alluvial fans, and that pediments are almost entirely erosional while the fans are depositional. Riverine landform patterns comprise a hierarchical classification (Table 12). The four types of flood plain differ in various ways, as set out in Table 13. ALF

Alluvial fan

level (less than 1% slope) to very gently inclined, complex landform pattern of extremely low relief. The rapidly migrating alluvial stream channels are shallow to moderately deep, locally numerous, but elsewhere widely spaced. The channels form a centrifugal to divergent, integrated, reticulated to distributary pattern. The landform pattern includes areas that are bar plains, being aggraded or eroded by frequently active channelled stream flow, and other areas comprising terraces or stagnant alluvial plains with slopes that are greater than usual, formed by channelled stream flow but now relict. Incision in the upslope area may give rise to an erosional stream bed between scarps. Typical elements: stream bed, bar, plain. Common element: scarp. Compare with Sheet-flood fan and Pediment.

58

Landform

Table 12 Classification of riverine landform patterns Low or very low relief More than one plain level

Terraced land (alluvial)

One plain level (seldom active or relict)

Terrace (alluvial)

Extremely low relief Undifferentiated

Alluvial plain

Inactive or barely active

Stagnant alluvial plain

Frequently active in sea or lake elsewhere undifferentiated differentiated

Delta Flood plain Bar plain Meander plain Covered plain Anastomotic plain

ALP

Alluvial plain

level landform pattern with extremely low relief. The shallow to deep alluvial stream channels are sparse to widely spaced, forming a unidirectional, integrated network. There may be frequently active erosion and aggradation by channelled and overbank stream flow, or the landforms may be relict from these processes. Typical elements: stream channel (stream bed and bank), plain (dominant). Common elements: bar, scroll, levee, backplain, swamp. Occasional elements: ox-bow, flood-out, lake. Included types of landform pattern are: flood plain, bar plain, meander plain, covered plain, anastomotic plain, delta, stagnant alluvial plain, terrace, terraced land.

ANA

Anastomotic plain

flood plain with slowly migrating, deep alluvial channels, usually moderately spaced, forming a divergent to unidirectional, integrated reticulated network. There is frequently active aggradation by overbank and channelled stream flow.

59

Shallow Rapid Reticulated Unidirectional

Depth/width

Migration

Stream-wise pattern

Network directionality

60 —

Minor

Ox-bow

Swamp

Levee

Scroll

bank

bar

Common

Typical

Typical

Typical

Typical Common

Common

Typical

Typical

Dominant

Channelled stream flow

Overbank stream flow

Aggraded

Divergent/ unidirectional

Reticulated

Slow

Deep

Moderately spaced

Anastomotic plain

Typical

Typical

Typical Dominant

stream bed

Typical

Dominant Typical

Typical

Typical

—

Overbank stream flow

Aggraded

Unidirectional

Non-tributary

Slow

Deep

Stream channel

Dominant

Overbank stream flow

Channelled stream flow

Eroded/aggraded

Unidirectional

Non-tributary

Rapid

Widely spaced

Covered plain

Type of flood plain

Moderately deep

Widely spaced

Meander plain

Backplain

Scroll plain

Landform elements

Channelled stream flow

Eroded/aggraded

Dominant

Geomorphological agent

Mode geomorphological activity

Numerous

Bar plain

Spacing

Stream channel

Attributes

Table 13 Discrimination between flood plains

Australian Soil and Land Survey Field Handbook

Landform

Typical elements: stream channel (stream bed and bank), levee, backplain (dominant). Common element: swamp. Compare with other types under Alluvial plain and Flood plain. BAD

Badlands

landform pattern of low to extremely low relief (less than 90 m) and steep to precipitous slopes, typically with numerous fixed, erosional stream channels which form a non-directional, integrated tributary network. There is continuously active erosion by collapse, landslide, sheet flow, creep and channelled stream flow. Typical elements: ridge (dominant), stream bed or gully. Occasional elements: summit surface, hillcrest, hillslope, talus. Compare with Mountains, Hills, Low hills, Rises and Plain.

BAR

Bar plain

flood plain with numerous rapidly migrating, shallow alluvial channels forming a unidirectional, integrated reticulated network. There is frequently active aggradation and erosion by channelled stream flow. (Described by Melton 1936.) Typical elements: stream bed, bar (dominant). Compare with other types under Alluvial plain and Flood plain.

BEA

Beach ridge plain

level to gently undulating landform pattern of extremely low relief on which stream channels are absent or very rare; it consists of relict, parallel beach ridges. Typical elements: beach ridge (co-dominant), swale (co-dominant). Common elements: beach, foredune, tidal creek. Compare with Chenier plain.

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Australian Soil and Land Survey Field Handbook

CAL

Caldera

rare landform pattern typically of very high relief and steep to precipitous slope. It is without stream channels or has fixed, erosional channels forming a centripetal, integrated tributary pattern. The landform has subsided or was excavated as a result of volcanism. Typical elements: scarp, hillslope, lake. Occasional elements: cone, hillcrest, stream channel.

CHE

Chenier plain

level to gently undulating landform pattern of extremely low relief on which stream channels are very rare. The pattern consists of relict, parallel, linear ridges built up by waves, separated by, and built over, flats (mud flats) aggraded by tides or overbank stream flow. Typical elements: beach ridge (co-dominant), flat (co-dominant). Common elements: tidal flat, swamp, beach, foredune, tidal creek. Compare with Beach ridge plain.

COR

Coral reef

continuously active or relict landform pattern built up to the sea level of the present day or of a former time by corals and other organisms. It is mainly level, with moderately inclined to precipitous slopes below the sea level. Stream channels are generally absent, but there may occasionally be fixed, deep, erosional tidal stream channels forming a disintegrated non-tributary pattern. Typical elements: reef flat, lagoon, cliff (submarine). Common elements: beach, beach ridge.

COV

Covered plain

flood plain with slowly migrating, deep alluvial channels, usually widely spaced and forming a unidirectional, integrated non-tributary network. There is frequently active aggradation by overbank stream flow. (Described by Melton 1936.) 62

Landform

Typical elements: stream channel (stream bed and bank), levee, backplain (dominant). Common element: swamp. Compare with other types under Alluvial plain and Flood plain. DEL

Delta

flood plain projecting into a sea or lake, with slowly migrating, deep alluvial channels, usually moderately spaced, typically forming a divergent, integrated distributary network. This landform is aggraded by frequently active overbank and channelled stream flow that is modified by tides. Typical elements: stream channel (stream bed and bank), levee, backplain (co-dominant), swamp (co-dominant), lagoon (co-dominant). Common elements: beach ridge, swale, beach, estuary, tidal creek. Compare with other types under Alluvial plain, Flood plain and Chenier plain.

DUN

Dunefield

level to rolling landform pattern of very low or extremely low relief without stream channels, built up or locally excavated, eroded or aggraded by wind. Typical elements: dune or dunecrest, duneslope, swale, blow-out, risecrest, residual rise, riseslope. Common elements: hummocky dune, barchan dune, parabolic dune, linear dune. Included types of landform pattern are: longitudinal dunefield, parabolic dunefield.

ESC

Escarpment

steep to precipitous landform pattern forming a linearly extensive, straight or sinuous, inclined surface, which separates terrains at different altitudes; a plateau is commonly above the escarpment. Relief within the landform pattern may be high (hilly) or low (planar). The upper margin is often marked by an included cliff or scarp. 63

Australian Soil and Land Survey Field Handbook

Typical elements: hillcrest, hillslope, clifffootslope. Common elements: cliff, scarp, scarp-footslope, talus, footslope, alcove. Occasional element: stream bed. FLO

Flood plain

alluvial plain characterised by frequently active erosion and aggradation by channelled or overbank stream flow. Unless otherwise specified, ‘frequently active’ is to mean that flow has an Average Recurrence Interval of 50 years or less. Typical elements: stream channel (stream bed and bank), plain (dominant). Common elements: bar, scroll, levee, backplain, swamp. Occasional elements: ox-bow, flood-out, scroll. Included types of landform pattern are: bar plain, meander plain, covered plain, anastomotic plain. Related relict landform patterns are: stagnant alluvial plain, terrace, terraced land (partly relict).

HIL

Hills

landform pattern of high relief (90–300 m) with gently inclined to precipitous slopes. Fixed, shallow, erosional stream channels, closely to very widely spaced, form a non-directional or convergent, integrated tributary network. There is continuously active erosion by wash and creep and, in some cases, rarely active erosion by landslides. Typical elements: hillcrest, hillslope (dominant), drainage depression, stream bed. Common elements: footslope, alcove, valley flat, gully. Occasional elements: tor, summit surface, scarp, landslide, talus, bench, terrace, doline. Compare with Mountains, Low hills, Rises and Plain.

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Landform

KAR

Karst

landform pattern of unspecified relief and slope (for specification use the terms in Table 5, e.g. ‘Karst rolling hills’) typically with fixed, deep, erosional stream channels forming a non-directional, disintegrated tributary pattern and many closed depressions without stream channels. It is eroded by continuously active solution and rarely active collapse, the products being removed through underground channels. Typical elements: hillcrest, hillslope (dominant), doline. Common elements: summit surface, valley flat, plain, alcove, drainage depression, stream channel, scarp, footslope, landslide. Occasional element: talus.

LAC

Lacustrine plain

level landform pattern with extremely low relief formerly occupied by a lake but now partly or completely dry. It is relict after aggradation by waves and by deposition of material from suspension and solution in standing water. The pattern is usually bounded by wave-formed features such as cliffs, rock platforms, beaches, berms and lunettes. These may be included or excluded. Typical element: plain. Common elements: beach, cliff. Occasional elements: rock platform, berm. Compare with Playa plain.

LAV

Lava plain

level to undulating landform pattern of very low to extremely low relief typically with widely spaced, fixed, erosional stream channels that form a non-directional, integrated or interrupted tributary pattern. The landform pattern is aggraded by volcanism (lava flow) that is

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Australian Soil and Land Survey Field Handbook

generally relict; it is subject to erosion by continuously active sheet flow, creep, and channelled stream flow. Typical elements: plain, hillslope, stream bed. Occasional element: tumulus. LON

Longitudinal dunefield

dunefield characterised by long, narrow sand dunes and wide, flat swales. The dunes are oriented parallel with the direction of the prevailing wind, and in cross-section one slope is typically steeper than the other. Typical elements: dune or dunecrest, duneslope, swale, blow-out. Compare with Parabolic dunefield.

LOW

Low hills

landform pattern of low relief (30–90 m) and gentle to very steep slopes, typically with fixed, erosional stream channels, closely to very widely spaced, which form a non-directional or convergent, integrated tributary pattern. There is continuously active sheet flow, creep, and channelled stream flow. Typical elements: hillcrest, hillslope (dominant), drainage depression, stream bed. Common elements: footslope, alcove, valley flat, gully. Occasional elements: tor, summit surface, landslide, doline. Compare with Mountains, Hills, Rises and Plain.

MAD

Made land

landform pattern typically of very low or extremely low relief and with slopes either level or very steep. Sparse, fixed, deep, artificial stream channels form a non-directional, interrupted tributary pattern. The landform pattern is eroded and aggraded, and locally built up or excavated, by rarely active human agency. Typical elements: fill-top (dominant), cut-over

66

Landform

surface, cut face, embankment, berm, trench. Common elements: mound, pit, dam. MAR

Marine plain

plain eroded or aggraded by waves, tides, or submarine currents, and aggraded by deposition of material from suspension and solution in sea water, elevated above sea level by earth movements or eustasy, and little modified by subaerial agents such as stream flow or wind. Typical element: plain. Occasional elements: dune, stream channel.

MEA

Meander plain

flood plain with widely spaced, rapidly migrating, moderately deep alluvial stream channels which form a unidirectional, integrated non-tributary network. There is frequently active aggradation and erosion by channelled stream flow with subordinate aggradation by overbank stream flow. (Described by Melton 1936.) Typical elements: stream channel (stream bed, bank and bar), scroll, scroll plain (dominant). Common element: ox-bow. Compare with other types under Alluvial plain and Flood plain.

MET

Meteor crater

rare landform pattern comprising a circular closed depression (see crater landform element) with a raised margin; it is typically of low to high relief and has a large range of slope values, without stream channels, or with a peripheral integrated pattern of centrifugal tributary streams. The pattern is excavated, heaved up and built up by a meteor impact and is now relict. Typical elements: crater (scarp, talus, footslope and plain), hillcrest, hillslope.

MOU

Mountains

landform pattern of very high relief (greater than 300 m) with moderate to precipitous slopes and

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Australian Soil and Land Survey Field Handbook

fixed, erosional stream channels that are closely to very widely spaced and form a non-directional or diverging, integrated tributary network. There is continuously active erosion by collapse, landslide, sheet flow, creep, and channelled stream flow. Typical elements: hillcrest, hillslope (dominant), stream bed. Common elements: talus, landslide, alcove, valley flat, scarp. Occasional elements: cirque, footslope. Compare with Hills, Low hills, Rises and Plain. PAR

Parabolic dunefield

dunefield characterised by sand dunes with a long, scoop-shaped form, convex in the downwind direction so that its trailing arms point upwind; the ground plan, when developed, approximates the form of a parabola. Where many parabolic dunes have been active, the trailing arms give the impression of a longitudinal dunefield. Typical elements: dune or dunecrest, duneslope, swale, blow-out. Compare with Longitudinal dunefield.

PED

Pediment

gently inclined to level (less than 1%) landform pattern of extremely low relief, typically with numerous rapidly migrating, very shallow incipient stream channels, which form a centrifugal to diverging, integrated reticulated pattern. It is underlain by bedrock, eroded, and locally aggraded, by frequently active channelled stream flow or sheet flow, with subordinate wind erosion. Pediments characteristically lie downslope from adjacent hills with markedly steeper slopes. Typical elements: pediment, plain, stream bed. Compare with Sheet-flood fan and Alluvial fan.

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Landform

PEP

Pediplain

level to very gently inclined landform pattern with extremely low relief and no stream channels, eroded by barely active sheet flow and wind. Largely relict from more effective erosion by stream flow in incipient stream channels as on a pediment. (Described by King 1953.) Typical element: plain.

PNP

Peneplain

level to gently undulating landform pattern with extremely low relief and sparse, slowly migrating alluvial stream channels which form a non-directional, integrated tributary pattern. It is eroded by barely active sheet flow, creep, and channelled and overbank stream flow. (Described by Davis 1889.) Typical elements: plain (dominant), stream channel.

PLA

Plain

level to undulating or, rarely, rolling landform pattern of extremely low relief (less than 9 m). Compare with Mountains, Hills, Low hills and Rises.

PLT

Plateau

level to rolling landform pattern of plains, rises or low hills standing above a cliff, scarp or escarpment that extends around a large part of its perimeter. A bounding scarp or cliff landform element may be included or excluded; a bounding escarpment would be an adjacent landform pattern. Typical elements: plain, summit surface, cliff. Common elements: hillcrest, hillslope, drainage depression, rock flat, scarp. Occasional element: stream channel.

PLY

Playa plain

level landform pattern with extremely low relief, typically without stream channels, aggraded by rarely active sheet flow and modified by wind, waves, and soil phenomena.

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Australian Soil and Land Survey Field Handbook

Typical elements: playa, lunette, plain. Compare with Lacustrine plain. RIS

Rises

landform pattern of very low relief (9–30 m) and very gentle to steep slopes. The fixed, erosional stream channels are closely to very widely spaced and form a non-directional to convergent, integrated or interrupted tributary pattern. The pattern is eroded by continuously active to barely active creep and sheet flow. Typical elements: hillcrest, hillslope (dominant), footslope, drainage depression, riseslope. Common elements: valley flat, stream channel. Occasional elements: gully, fan, tor. Compare with Mountains, Hills, Low hills and Plain.

SAN

Sand plain

level to gently undulating landform pattern of extremely low relief and without channels; formed possibly by sheet flow or stream flow, but now relict and modified by wind action. Typical element: plain. Occasional elements: dune, playa, lunette.

SHF

Sheet-flood fan

level (less than 1% slope) to very gently inclined landform pattern of extremely low relief with numerous rapidly migrating, very shallow incipient stream channels forming a divergent to unidirectional, integrated or interrupted reticulated pattern. The pattern is aggraded by frequently active sheet flow and channelled stream flow, with subordinate wind erosion. Typical elements: plain, stream bed. Compare with Alluvial fan and Pediment.

STA

Stagnant alluvial plain

alluvial plain on which erosion and aggradation by channelled and overbank stream flow is barely active or inactive because of reduced water supply,

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Landform

without apparent incision or channel enlargement that would lower the level of stream action. Typical elements: stream channel (stream bed and bank), plain (dominant). Common elements: bar, scroll, levee, backplain, swamp. Occasional elements: ox-bow, flood-out, lake. Compare with Flood plain and Terrace. TER

Terrace (alluvial)

former flood plain on which erosion and aggradation by channelled and overbank stream flow is barely active or inactive because deepening or enlargement of the stream channel has lowered the level of flooding. A pattern that has both a former flood plain and a significant, active flood plain, or that has former flood plains at more than one level, becomes terraced land. Typical elements: terrace plain (dominant), scarp, channel bench. Occasional elements: stream channel, scroll, levee.

TEL

Terraced land (alluvial)

landform pattern including one or more terraces and often a flood plain. Relief is low or very low (9–90 m). Terrace plains or terrace flats occur at stated heights above the top of the stream bank. Typical elements: terrace plains, terrace flats, scarps, scroll plain, stream channel. Occasional elements: stream channel, scroll, levee.

TID

Tidal flat

level landform pattern with extremely low relief and slowly migrating, deep alluvial stream channels, which form non-directional, integrated tributary patterns; it is aggraded by frequently active tides. Typical elements: plain (dominant), intertidal flat, supratidal flat, stream channel. Occasional elements: lagoon, dune, beach ridge, beach.

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Australian Soil and Land Survey Field Handbook

VOL

Volcano

typically very high and very steep landform pattern without stream channels, or with erosional stream channels forming a centrifugal, interrupted tributary pattern. The landform is built up by volcanism, and is modified by erosional agents. Typical elements: cone, crater. Common elements: scarp, hillcrest, hillslope, stream bed, lake, maar. Occasional element: tumulus.

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V EG E TAT ION R.J. Hnatiuk, R. Thackway and J. Walker

This chapter identifies which vegetation attributes should be measured and recorded at field sites in order to describe and classify Australian vegetation.7 The attributes chosen – as well as the required level of detail – depend on the purpose of the survey, which needs to be explicitly recorded. Here we expand the previous version of this chapter (Walker and Hopkins 1990) to include wetlands, temperate rainforests, vegetation growth stage and vegetation condition. Other changes include new height classes, an increased number of broad floristic groups, and different codes for some attributes. We have also made several changes to the terms used to name vegetation units, based on their cover and broad floristic composition (see Table 21). The largest of these changes is the replacement of the terms ‘forest’ and ‘woodland’ with ‘trees’, and the deletion of the suffix ‘land’ from many of the units in the table. The translation from ‘trees’ to ‘woodland’, where it is relevant to certain users, is simple. These changes remove a number of anomalies and make the underlying importance of cover classes clear throughout the classification. Details of the rationale for these changes can be found in Hnatiuk et al. (2008). This chapter is available online (Hnatiuk et al. 2009) with hyperlinks to the additional information found in Hnatiuk et al. (2008). The field data collected with these new methods are currently classified, coded and named differently than in the National Vegetation Information 7

The Executive Steering Committee for Australian Vegetation Information (ESCAVI) has endorsed this chapter as guidelines for the collection of site-based data on vegetation in Australia.

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Australian Soil and Land Survey Field Handbook

System (NVIS) framework (ESCAVI 2003). Where there is a need to classify and map these field data according to the vegetation map units listed in the NVIS, we recommend users consult Thackway et al. (2008) and updates in Hnatiuk et al. (2008). Starting in 2008, NVIS will be changed progressively to match the classification in this chapter. Before setting out into the field there are many aspects to consider. Guidance on timing, sample site location, sample detail and recording sheets for vegetation and ancillary information are outlined in Thackway et al. (2008) and Hnatiuk et al. (2008). Here we briefly address the choice of sample site location. The historical approach is to locate sample sites within examples of native vegetation that are intact (i.e. not overly disturbed) and mature (i.e. not regeneration stages). Such sites are often called ‘potential vegetation’ (e.g. Carnahan 1977) representing the vegetation that sites with similar environments and disturbance regimes are expected to support at maturity. There is, however, increasing interest in successional (seral) stages of vegetation, from disturbance through recovery, maturing to senescence and subsequent disturbance. In some cases the dominant and other species will be replaced progressively by new species. Regular resampling can help elucidate these changes. Vegetation samples collected in conjunction with fauna studies or restoration activities may also span different stages in the vegetation succession or recovery. These stages are likely to provide different fauna habitats and may also need to be recorded. Vegetation data are also used in habitat models, impacts of climate change, soil–water balances, disturbance impacts, restoration of disturbed sites, carbon sequestration and potential fuel loads. This chapter describes how to obtain the recommended core data for a standard classification as well as additional data about growth stage and condition required for these uses. Most vegetation studies in Australia and elsewhere have concentrated on native plants in their natural habitats. The methods presented here are particularly suited to such studies and are also suitable for agricultural and horticultural vegetation (e.g. Abed and Stephens 2003; McNaught et al. 2006; Thackway and Lesslie 2006; BRS 2007). The vegetation structure of a wheat field, a cotton crop, a vineyard or a grazing paddock can all be sampled and reported with the methods presented here. Using a single comprehensive system to record all vegetation enables all vegetation of a landscape, region or continent to be integrated into a single system, which can then be used for holistic planning, assessment or modelling. 74

Vegetation

OVERVIEW OF THE CLASSIFICATION Vegetation is classified on the basis of structure (the vertical and horizontal distribution of vegetation: its growth form, height, cover and strata) and floristics (the dominant genera or species in various strata and characteristic plant species). We initially use three levels of detail: the broadest units, formations; next structural formations; and the more detailed, broad floristic formations, as shown in Table 14 with examples in Table 15. Further subdivision to include more strata or plant species is possible. The level to use will depend on the purpose of the survey and the resources available. As seen in Table 16, these levels are conceptually equivalent to levels in NVIS and add a broad level intended for use with imagery (formation, i.e. woody or non-woody plant) to the previously recommended system (Walker and Hopkins 1990). The levels of classification used here are defined as follows: s Level 1 – Formations are classified based on cover and whether the dominant plants are woody or non-woody. Formation is usually assessed from imagery before the field survey. s Level 2 – Structural formations are classified and named on the basis of height, cover and growth form (e.g. tree, shrub, grass; see ‘Growth forms’ (page 88) for complete list of growth forms). s Level 3 – Broad floristic formations are defined by adding genus or species names to the structural formation name in the order of height, cover, species and growth form. The dominant species in the dominant stratum is used. s Additional levels – Dominant species in other layers are added to give broad floristic subformations and the ‘associations’ of other classification systems (equivalent to NVIS Levels IV to VI). The progression from the simplest to a more detailed vegetation classification is shown by the example of Eucalyptus populnea vegetation with height of 21 metres and crowns nearly touching. Using the appropriate tables, this vegetation can be classified at different levels with the addition of progressively more detailed descriptions (Table 15 and Figure 8, page 104). It is desirable to classify vegetation not only by a name but also with a code. A coding system for vegetation is essential for data storage and retrieval, air-photo marking and mapping. The codes must be computer compatible and 75

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8. Species of only the dominant stratum (pages 95–7)

7. Emergents (if any) (page 94)

6. Foliage cover of the lower strata (page 94)

5. Height (see Table 20, page 95) of each stratum

4. Growth forms (page 88) in each stratum

3. Crown type (see Figure 6, page 85)

2. Cover of the dominant stratum (crown separation or foliage cover, see Table 17, page 81)

1. Life form (woody or non-woody plant) (page 80)

Ground stratum (if present)

Mid-stratum (if present)

Dominant stratum (page 79)

Attributes required

Formation (Level 1): record 1–2

Level of detail

Structural formation (Level 2): record 1–7

NB: Defining Levels 4–6 requires the addition of more strata and dominant species in each stratum (see Figure 8, page 104).

Record (for at least the dominant and ground stratum)

Recognise

Table 14 Attributes required to define Levels 1, 2 and 3

Broad floristic formation (Level 3): record 1–8

Australian Soil and Land Survey Field Handbook

Vegetation

Table 15 Examples of the classification levels Level

Name

Notes

Level 1 – Formation

‘Mid-dense woody plants’

Table 17 (see page 81) and life form (woody or non-woody plant)

Level 2 – Structural formation

‘Emergents over very tall mid-dense trees’

Tables 20 and 21 (see pages 95 and 98)

Level 3 – Broad floristic formation

‘Emergent very tall Angophora over very tall mid-dense Eucalyptus trees’

Tables 20 and 21 and floristics

Level 4 – Broad floristic subformation

‘Emergent very tall Angophora trees over very tall mid-dense Eucalyptus trees with tall sparse Eucalyptus tree understorey over dwarf very sparse Eremophila shrubs with a tall sparse Bothriochloa tussock grass ground stratum’

Tables 20 and 21 and floristics

applicable at different levels of detail. Codes for vegetation have been assigned for cover, height, growth form and species or genera and are described in the remainder of the chapter. This standard classification can be applied to all vegetation: native (including rainforest) and non-native. This chapter describes how to classify vegetation according to this standard method. First we describe how to recognise strata, and then how to measure attributes required for classification in increasing detail (Levels 1, 2 and then 3). Some vegetation types, however, may require further detail, as explained in the final part of this chapter. Wetlands, for example, require extra attributes to separate otherwise indistinct types. Rainforests can also be treated as special cases. Some rainforests may be adequately described by the standard classification. Others – such as wet tropical/subtropical or cool temperate Tasmanian rainforests – require additional attributes. The chapter concludes with guidelines to add even more detail by assessing growth stage and condition.

RECOGNISING STRATA A stratum is an easily seen layer of foliage and branches of a measurable height. Vegetation can have one or more strata. A single stratum may extend 77

78 Species can be added for substrata (see Figure 8)

Above, plus the dominant genera for each stratum (upper, mid and ground)

Above plus the five dominant or co-dominant species in each stratum

4 / Broad floristic subformation

Growth form, cover, height and characteristic species/genera in the dominant stratum

Species can be added for substrata (see Figure 8, page 104)

3 / Broad floristic formation

Growth form, cover and height of the dominant stratum and emergents

Above plus the three dominant or co-dominant species in each stratum

1 / Formation 2 / Structural formation

Life form and cover

This publication (Level / name)

Key attributes

Table 16 Comparison of vegetation classification systems

VI / Subassociation

V / Association

IV / Broad floristic subformation

III / Broad floristic formation

II / Structural formation

I / Class

NVIS (ESCAVI 2003) (Level / name)

Structural subformation (page 74 in Walker and Hopkins (1990)) – above, plus additional species

Floristic association – the structural formation plus characteristic species/genera in the dominant stratum (see page 76 in Walker and Hopkins (1990))

Structural formation (see pages 60–1 in Walker and Hopkins (1990))

NA

Walker and Hopkins (1990) (Name)

Australian Soil and Land Survey Field Handbook

Vegetation

from the top of the canopy to near ground level. Record the median height of the top of each stratum in metres (see Figure 8, page 104). If foliage profiles are required for the habitat studied, also record the depth of the crowns in each stratum. Strata are named as follows: U

Dominant or In most cases, the tallest stratum will be the upper stratum dominant stratum. Emergents are an exception (see ‘Emergents’).

M

Mid-stratum

if present, is between the dominant stratum and the lowest or ground stratum. When present, there are no preconceived height limits for this stratum. Record actual heights and fit into classes later.

G

Ground stratum

can also be the dominant stratum (e.g. in places where grass cover is closed and trees are very sparse). No mandatory height limit on the ground layer, but it is usually less than 2.0 m tall.

At times it will be useful to record subdivisions of the three main strata. These substrata occur when a major stratum is composed of two or more different elements. For example, the dominant stratum may consist of one species that makes up most of the canopy, but its lower limit is made up mostly of a different species, a co-dominant. In such cases, separate strata do not really exist, but recognising a substratum may make it possible to elucidate a significant aspect of the vegetation (e.g. development stage or species mixtures).

Emergents The tallest plants in some vegetation are so sparse that they no longer form the dominant or most significant layer. For example, a few tall Araucaria or Eucalyptus trees may rise above a closed rainforest canopy, or widely scattered eucalypts or acacias may rise above lower shrubs or grasses in semiarid regions. The tallest stratum is then classified as an ‘emergent layer’ (see ‘Emergents’, page 94, for definition and discussion) and the dominant layer on which the vegetation will be classified is usually the next tallest layer.

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Complex canopies due to regrowth Vegetation that has been disturbed or is still recovering from certain kinds of disturbance can produce complex canopies. For example, where a canopy has been reduced – but not totally removed – by clearing, ringbarking or poisoning, two or more cohorts of canopy species may occur. When of clearly different ages, the cohorts are also likely to differ in height, making the description of the canopy difficult. The methods already described for defining dominant stratum and emergents should be applied. This type of vegetation can be further characterised by recording ‘uneven age’ when assessing growth stage (see Table 28). The different cohorts should not be amalgamated unless they are too similar in structure to be distinguished consistently. Arbitrary height boundaries should not be used to separate them.

FORMATION (LEVEL 1) Life form Life form describes what a plant looks like. At the most general level of classification, formations, there are only two life forms: woody plants (w) and non-woody plants (nw). Woody plants include all trees, palms, arborescent cycads, tree ferns, xanthorrhoeas, shrubs and woody vines. All other plants with little or no woody tissue are classified as non-woody including annuals, grasses, grass-like plants, forbs, crusts, bryophytes and algae.

Cover and crown type The recorded cover values collected using the methods below can be converted to cover classes as shown in Table 17. Crown cover classes are those used in Walker and Hopkins (1990) and these were selected to coincide as closely as possible with the cover classes of previous classifications (e.g. the projective foliage cover classes of Specht et al. 1974). The three commonly used field measures of cover are: crown cover, foliage cover and projective foliage cover. Each gives different values and none is correlated in a simple way with leaf area or leaf area index. Crown cover (C) (Walker and Hopkins 1990) is the percentage of the sample site within the vertical projection of the periphery of the crowns with

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Vegetation

Table 17 Cover classes can be derived in several ways

Description

Crown separation ratio

D

Crowns touching to overlapping

Closed or dense

<0

>80%

>70%

M

Crowns touching or slightly separated

Mid-dense

0–0.25

50–80%

30–70%

S

Crowns clearly separated

Sparse or open

0.25–1

20–50%

10–30%

V

Crowns well separated

Very sparse

1–20

0.25–20%

0.2–10%

I

Isolated plants: for trees about 100 m apart, shrubs about 20 m apart

Isolated plants

>20

<0.25%

<0.20%

L

Isolated clumps of 2 to many plants about 200 m apart

Isolated clumps

>20

<0.25%

<0.20%

E

Emergent

Emergent

>3

<5% of total crown cover

<3% of total foliage cover

Code

Criteria assessed in field

Crown cover %a

Foliage cover %a

a The relationship between crown cover and foliage cover is described in more detail in the text.

the crowns considered to be opaque. This is also the generic definition of canopy cover or plant cover. Foliage cover (Carnahan 1977; Walker and Hopkins 1990) is the percentage of the sample site occupied by the vertical projection of foliage and woody branches. Projective foliage cover (PFC) (Specht et al. 1974) is the percentage of the sample site occupied by the vertical projection of foliage only. PFC and foliage cover for plants are sensitive to season and drought because foliage may change greatly depending on the water available. This variation is not usually considered in vegetation classification. Crown cover is the recommended method for reporting cover for plants with discrete crowns and these are usually over about 1.0 m high. Foliage

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cover can be estimated from crown cover. This approach avoids the problem of variability due to season or water availability. Cover can be estimated both in the field and from large-scale aerial photographs. Crown cover percentage is estimated using the crown separation ratio (CSR) developed by Penridge and Walker (1988) and Walker et al. (1988). However, CSR is not reliable if crowns deviate significantly from circular or slightly oval (e.g. in forests with a significant cover of Corymbia that have very irregular and interlocking shapes). Ground cover can be estimated by measuring the distance covered by the vertical projection of the leaves and woody branches onto a tape measure and expressing this as a percentage of the total length. This is a line-intercept method. Cover class for a particular stratum can be quickly assessed based on the crown separation (e.g. touching, well separated). However, because primary data such as actual crown cover percentage are usually more valuable than pre-classified data, a method to accurately estimate the crown separation ratio is needed.

Field estimation of the crown separation ratio for discrete crowns The CSR is the ratio of the mean gap between crowns and the mean crown width, that is: CSR = mean gap between crowns/mean crown width. The three steps to estimating CSR in the field are: 1. Sample along a zigzag transect PQ as shown in Figure 5. Start at a crown near P (crown A), and select the next crown encountered going towards or across the transect line, and in the direction P to Q. 2. Measure crown widths and crown gaps for each stratum separately irrespective of species. A mean of 12 measurements is usually sufficient. 3. Where crowns overlap, the crown gap has a negative value; the greater the overlap, the larger the negative value. The method has been shown by Penridge and Walker (1988) to work well whether crowns are regularly spaced, random or clumped. However, they also note limitations that will apply in some field situations. These are: s CSR should be measured for each stratum separately to avoid situations where crowns overlap. 82

Vegetation

s Crown shapes should approximate circles or non-extreme ellipses. Where crown shapes are so irregular that a near-circular equivalent cannot be determined, an alternative method (e.g. a line-intercept method) should be used to determine cover. For ovoid crowns, average the shortest and longest diameters. s The zigzag method of measurement should be used to avoid long distances between trees, which could invalidate the underlying geometric assumptions of the method. To convert between crown separation ratio and crown cover percentage (Table 18), use the following relationship: Crown cover (%) =

k (1 + CSR) 2

The constant k = 80.6 for samples taken along a zigzag transect as shown in Figure 5 (Penridge and Walker 1988).

Converting crown cover percentage to foliage cover Estimating crown cover percentage assumes the crown is opaque. Converting crown to foliage cover requires that the degree of crown openness be considered. Crown openness can be assessed by matching the photographs in Figure 6 with actual tree crown types. Foliage cover percentage = crown cover percentage × crown type. For example: s If CSR is 1.0, crown cover percentage = 20%. s If crown openness (Figure 6) is 60%, then: foliage cover percentage =

20 # 60 = 12% 100

Ground cover The ground layer normally comprises low shrubs, grasses, forbs, rushes and sedges and it is necessary, in this classification, to estimate the foliage cover as a vertical projection. For many purposes a visual estimate will suffice to place the ground cover into a cover class (Table 17). Foliage cover of the ground layer may be accurately estimated using point quadrats or foliar intercepts along transects. A rapid field method uses foliar intercepts along a 30 m tape laid out within the sample site (Figure 7). 83

84

81

73

11

67

0.05 0.1

6

A

2

5

9

60

P

4

8

10

Q

56

0.15 0.2

1

3

7

52

48

0.25 0.3

(a)

41

0.4

34

0.5

31

0.6

26

P

Q

20

0.75 1

16

13

1.25 1.5

(b)

9

2

5

3

3

4

1

8

15

20

30

0.6 0.3 0.2 0.1

10

Figure 5 The zigzag sampling procedure is used for each stratum or layer, for example (a) for the dominant stratum or (b) for a mid-stratum.

84

89

Crown cover (%)

100

–0.05 –0.02 0

Crown separation ratio –0.1

Table 18 Converting crown separation ratio to crown cover

Australian Soil and Land Survey Field Handbook

Vegetation

Figure 6 Crown types. Estimate the openness of individual tree or shrub crowns by matching the crown with a photograph. The rows show similar crown types for different leaf size (large to small, left to right). Acacia phyllodes are in the right-hand column. Most Australian woody plants are in the range 40–70%.

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Australian Soil and Land Survey Field Handbook

0

2.5

22cm intercept

20 cm intercept

10m

10 cm intercept

52cm intercept in 250 cm = 20.8%

Figure 7 Field measurement of foliage cover using a line transect. The length of intercepted foliage is measured along a tape and foliage cover is calculated as a percentage of the total length of the transect.

The method is intended for use in grass and low shrubs. Looking vertically down onto the tape and foliage, the amount of foliage intercepted along the tape is estimated, and expressed as a percentage of the transect length. It is easiest to estimate and record the amount of foliage intercepted per metre of tape and to add these amounts at the completion of the transect. Two to four transects are usually needed per site depending on cover variability. For grass, a 10 m transect is usually enough; for small shrubs, 20 m. A longer transect will be needed where the ground layer is more patchy. In some situations – for example rangeland environments where the formation class may require subdivision – it is often useful to collect information about basal area and/or plant density and to record several cover classes in the <10% foliage cover class. Transects should be located independently of the ground layer so that the sample is not biased. The starting point and direction can be fixed in relation to some aspect of the plot or can be determined by using random numbers to locate the starting point and bearing. Cover–abundance combines cover and abundance to estimate the quantity of each species in a vegetation sample. For cover values greater than 5%, the scale is a measure of cover (see above). For cover values less than 5%, it measures abundance (i.e. the number of individuals in a defined area). The Braun-Blanquet cover–abundance scale (Table 19) is widely used. It is simple to use and produces estimates of cover–abundance that are robust for most vegetation classifications. The system is based on the fact that vegetation is often highly variable and so it is more useful to have many samples to show this variation than to have few precise and time-consuming measures.

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Table 19 The Braun-Blanquet cover–abundance scale for estimating species quantities (after Mueller-Dombois and Ellenberg (1974)) Code

Description

Crown cover percentage

5

Any number of plants covering more than ¾ of the sample site

>75%

4

Any number of plants covering from ½ to ¾ of the sample site

50–75%

3

Any number of plants covering ¼ to ½ of the sample site

25–50%

2

Any number of plants covering from 1/20 to ¼ of the sample site

5–25%

1

Many individuals that cover <1/20 of the sample site, or scattered with cover up to 1/20 of the sample site

<5%

+

(pronounced ‘cross’) Few individuals with small cover

Insignificant cover

r

Single individual with small cover

Insignificant cover

Record the cover class code values for the class that represents each species at the sample site. For the less dense cover classes, imagine moving all individuals into one area and compare that with a reference for the sample site. For example, if the sample site is 400 m2, 5% of the area is 20 m2 (4 m × 5 m), and 1% is 4 m2 (2 m × 2 m). Although this method provides an absolute value for classes 2–5 (i.e. it is a percentage of a defined sample area), the class boundaries are wide and cover is estimated, not measured. Many studies have shown large variations between observers, as well as in one observer’s estimates at different times. Because of these inherent errors, it is important to regularly compare observers if more than one person is making records and to check observations if one person is recording. In broad-ranging surveys, it is usually better to have large numbers of samples with good cover–abundance estimates, rather than a few precise measures that do not span the range in variation of the vegetation. If the objectives of the survey are narrowly focused and looking for fine levels of discrimination between samples or sampling times (e.g. site-based monitoring), then actual quantitative measurements are more appropriate than class values.

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STRUCTURAL FORMATION (LEVEL 2) Growth form At Level 1, only two life forms exist (woody plants or non-woody plants). In contrast, at Level 2, many more detailed categories of growth forms are used. The term growth form is used in a broad sense to describe the form or shape of individual plants (e.g. tree, shrub) or Australian broad floristic land cover types (e.g. native vegetation such as mallee, chenopod shrub; or non-native vegetation such as wheat fields, orchards). The following glossary (modified from ESCAVI 2003 and alphabetised by growth form name) defines the growth forms for structural formations. Growth form Algae: fresh or brackish

Code

Definition

a3.0

a member of the Chlorophyta, Cyanophyta, Phaeophyta or Rhodophyta living in fresh or brackish aquatic environments.

Algae: marine

a4.0

a member of the Chlorophyta, Cyanophyta, Phaeophyta or Rhodophyta living in marine environments. May range from thin surfacehugging layers to tall algal forests.

Aquatic higher plants

a1.0 (or w)

dicotyledonous or monocotyledonous plants growing for a significant portion of their life cycle in fresh or brackish water. (For convenience, this may include various woody vegetation such as mangroves, eucalypt, melaleuca or other woody, periodically submerged vegetation, which span saline aquatic environments from brackish to hypersaline. The code used (a1.0 or w) will depend on the particular emphases of the survey.)

Bare surface

b1.0

soil, rock or water surfaces with less than 0.5% plant cover.

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Bryophyte

m1.0

a member of the Division Bryophyta (i.e. mosses and liverworts). Mosses are small plants usually with a slender leaf-bearing stem with no true vascular tissue. Liverworts often appear moss-like or consist of a flat, ribbon-like, green thallus.

Chenopod shrub

w3.2

single-stemmed or multi-stemmed, semisucculent shrub of the family Chenopodiaceae exhibiting drought and salt tolerance.

Cryptogam Fern (excluding tree ferns)

cryptogam refers collectively to lichens and bryophytes. f1.0

Food

a member of the Division Pterophyta (i.e. ferns and fern allies). Characterised by large and usually branched leaves (fronds); herbaceous and terrestrial to aquatic; spores in sporangia on the undersides of leaves. Tree ferns are classified with woody plants as they have the same vegetation structure. see Shrub: planted/cultivated (food) or Tree: planted/cultivated (food).

Forb

h1.0

non-graminoid herbaceous plant.

Grass

g1.0

member of the family Poaceae.

Grass: planted/ cultivated

g4.0

member of the Poaceae planted or cultivated for specific human uses (e.g. human or other animal food, lawn or other ground cover).

Grass: planted/ cultivated (pasture)

g4.1

member of the Poaceae cultivated or maintained for the production of food for animals, whether harvested or grazed directly.

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Grass: planted/ cultivated (cereals)

g4.2

member of the Poaceae cultivated as cereal food for human consumption.

Grass: planted/ cultivated (other industrial)

g4.3

member of Poaceae cultivated or maintained for industrial purposes but not for food (e.g. turf farm for lawn-grasses, road batten stabilisation).

Heath or kwongan or wallum shrub

w3.1

shrub usually less than 2 m tall, commonly with ericoid leaves (nanophyll, less than 225 mm2). Often a member of one of the following families: Epacridaceae, Myrtaceae, Fabaceae and Proteaceae. Commonly occur on nutrient-poor substrates.

Herb

h2.0

herbaceous or slightly woody, annual or sometimes perennial plant (dicotyledon or monocotyledon).

Herb: planted/ cultivated (perennial, non-food)

h2.1

planted/cultivated perennial herbaceous plant (monocotyledon or dicotyledon); non-food.

Herb: planted/ cultivated (annual, non-food)

h2.2

planted/cultivated annual herbaceous plant (monocotyledon or dicotyledon); non-food.

Herb: planted/ cultivated (perennial, food)

h2.3

planted/cultivated perennial herbaceous plant (monocotyledon or dicotyledon); food.

Herb: planted/ cultivated (annual, food)

h2.4

planted/cultivated annual herbaceous plant (monocotyledon or dicotyledon); food.

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Hummock grass

g2.0

coarse xeromorphic grass with a mound-like form often dead in the middle; genera are Triodia, Plectrachne and Zygochloa.

Lichen

l1.0

composite plant consisting of a fungus living symbiotically with algae or cyanobacteria; without true roots, stems or leaves.

Mallee (tree or shrub)

w2.1

any of the eucalypt trees or shrubs with multiple stems arising from a lignotuber.

Rainforest

see Tree: rainforest.

Rush

g6.0

herbaceous, usually perennial, erect monocot that is neither a grass nor a sedge. For the purpose of this chapter, rushes include the monocotyledon families Juncaceae, Typhaceae, Liliaceae, Iridaceae, Xyridaceae and the genus Lomandra, i.e. ‘graminoid’ or grass-like genera.

Samphire shrub

w3.3

a subdivision of chenopod shrubs. Genera (of Tribe Salicornioideae, namely Halosarcia, Pachycornia, Sarcocornia, Sclerostegia, Tecticornia and Tegicornia) with articulate branches, fleshy stems and reduced flowers within the Chenopodiaceae family; succulent chenopods. Also the genus Suaeda.

Seagrass: marine

a2.0

genera and species of flowering angiosperms of the families Hydrocharitaceae and Potamogetonaceae, forming sparse to dense mats of material at the subtidal level and down to 30 m below mean sea level. Occasionally exposed.

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Australian Soil and Land Survey Field Handbook

Sedge

g5.0

herbaceous, usually perennial, erect plant generally with a tufted habit and of the families Cyperaceae (true sedges) or Restionaceae (node sedges).

Shrub

w3.0

woody plant, multi-stemmed at the base (or within about 200 mm from ground level), or, if single-stemmed, less than about 5 m tall; not always readily distinguishable from small trees.

Shrub: planted/ cultivated (food)

w3.4

shrubs planted in rows for the production of food crops.

Shrub: planted/ cultivated (non-food)

w3.5

shrubs planted in mostly urban/suburban settings such as gardens, along streets, and nurseries.

Surface crusts

c1.0

assemblages of one or more species of minute plants at or within the surface of soil or rock. May consist of bryophytes, lichens, cyanobacteria, green algae and fungi; may in some cases include very small vascular plants.

Tree

w1.0

woody plant more than 2 m tall usually with a single stem, or branches well above the base; not always distinguishable from large shrubs.

Tree: rainforest

w1.1

no widely accepted or universal definition for Australian rainforests. Usually distinguished by their dark green colour and species composition, which contrasts with the surrounding grey or reddish-green and often eucalypt-dominated vegetation.

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Vegetation

Tree: planted/ cultivated (non-food)

w1.2

trees planted in rows for the intense production of non-food crops.

Tree: planted/ cultivated (food)

w1.3

trees planted in rows for the production of food crops.

Tree: planted/ cultivated (landscaping)

w1.4

trees planted in mostly urban/suburban settings (e.g. gardens, along streets, and nurseries).

Tussock grass

g3.0

grasses forming discrete but open tufts usually with distinct individual shoots. These include the common agricultural grasses.

Vine

v1.0

climbing, twining, winding or sprawling plants usually with a woody stem.

Woody plant (indeterminate tree or shrub)

w2.0

plants with woody tissues. For the purposes of vegetation classification here, also those plants that achieve a growth form similar to that of woody plants (e.g. cycads, palms, tree ferns). Includes both trees and shrubs.

Cover and crown type At Level 2, cover and crown type are classified as described for Level 1 in the section ‘Cover and crown type’ (page 80).

Height In the field, height should be measured, rather than the height class estimated. Height can be measured using measuring tapes or poles for low vegetation. Clinometers, laser or sonic ranging instruments, visual sighting instruments or LIDAR can be used for tall vegetation (see Brack 1998; Abed and Stephens 2003). Inaccuracy in measurements increases as crown closure and height increases. Record the height from the ground to the highest part of the plant above ground. Where the height of flower stalks (e.g. in grasses, grass trees) or leaves

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(e.g. in palms, cycads, grass trees, tree ferns) add significantly to plant height and contribute significantly to a stratum, then record two measurements: total height from ground level to the top of the highest part of the plant, and height from ground level to the top of the leaves (e.g. Xanthorrhoea johnsonii 2.5 m/1.3 m; Sorghum intrans 1.9 m/1.3 m). This provides an accurate record and allows various uses in analysis. The recorded heights can then be converted to height classes as shown in Table 20.

Foliage cover of the lower stratum Use the methods described in the section ‘Cover and crown type’ (page 80) to classify the foliage cover of the lower stratum.

Emergents Some plants can rise above the level of the dominant stratum and because their total cover is small, they are considered to be emergents rather than a separate stratum. As a guideline, emergents are recognised if their foliage cover is less than 5% of the crown cover of the dominant stratum (see Figure 8 for a tree example). Care is needed in classifying tall plants as emergents, and the 5% guideline can be expected to vary depending on vegetation type and season – especially if the ground layer is the dominant stratum. In some borderline cases, taller plants can occur over a lower stratum that elsewhere forms the dominant stratum of a well-known vegetation type. In this situation it is acceptable to continue to call the tallest stratum emergents where it is considered unhelpful to create a new vegetation type solely on the basis of the unusually slightly higher cover of the tallest plants. Record the total crown cover percentage, median height and/or maximum height, and the genus (and species if possible) of the emergent layer. Measure height and cover as for other plant attributes described earlier. When the tallest stratum is not the most significant stratum, the guidelines vary for different kinds of vegetation as follows. s Where the vegetation is dominated by trees or shrubs, and the tallest layer emerges above a dominant canopy (i.e. cover >5%) and has generally less than 5% total cover, then the tallest trees or shrubs are called emergents. The genus or species of emergents should be recorded, if possible, followed by the word ‘emergents’ (e.g. ‘with hoop pine emergents’; ‘with Araucaria emergents’; ‘with Eucalyptus emergents’). 94

Vegetation

Table 20 Height classes, codes and names Height class code

Height (m)

Life form w (woody plants)

Life form nw (non-woody plants)

10

>50.01

Giant

NAa

9

35.01–50

Extremely tall

NA

8

20.01–35

Very tall

NA

7

10.01–20

Tall

NA

6

5.01–10

Medium

Giant

5

2.01–5.0

Low

Extremely tall

4

1.01–2

Dwarf

Very tall

3

0.51–1

Miniature

Tall

2

0.26–0.5

Micro

Medium

1

0.05–0.25

Nano

Low

0

<0.05

NA

Dwarf

a NA, not applicable.

s Where the vegetation is dominated by perennial grasses, for example Triodia, and a taller layer of woody plants emerges above it with less than 5% of the Triodia cover, then the tallest plants are called emergents and should be named as in the example above. s Where the vegetation is seasonally or sporadically dominated by annual plants in a mix of perennial plants that form a taller layer, then in most cases the dominant layer is the taller perennial layer. For example, ‘sparse eucalypt trees with seasonally dominant Sorghum in the understorey’ or ‘sparse acacia trees with periodically dominant annual herbs of Asteraceae and other families’. s For ephemeral wetlands, where the dominant layer is present only periodically and there is no taller woody layer, the dominant layer is the ephemeral layer. It is recorded as ephemeral (e.g. ‘ephemeral mixed herbs’).

BROAD FLORISTIC FORMATION (LEVEL 3) AND SUBDIVISIONS (LEVELS 4 TO 6) A species or genus name (shown as ‘X’ in Table 21, see page 98) is added to the structural formation name of Level 2 to give Level 3, the broad floristic 95

Australian Soil and Land Survey Field Handbook

formation. For Level 3, only the dominant species in the dominant stratum is used. More species names can be added to this stratum or to lower strata to distinguish vegetation types (and these added details result in levels conceptually equivalent to the more detailed levels IV–VI in NVIS). The method can be summarised as follows: s First species: Select the most abundant or physically predominant species in the dominant stratum. s Second species: If a second species is always present and conspicuous in the dominant stratum (a co-dominant species) then add that species to the name. If a co-dominant species is not present, select the most abundant or physically predominant species of the next most conspicuous stratum. s Third species: Select an indicator species, or a species that distinguishes a particular vegetation association. This may be in any stratum, but is usually in a lower stratum. This species will have known environmental preferences and will be conspicuously abundant. s Subsequent species: In some cases more species are required to separate subassociations; select as for the third species. The species selected in the field can be modified later based on numerical analysis or to conform to an agreed list of vegetation types. The main problem with using the dominant species to qualify the structural formation is that dominance can vary spatially. Due care needs to be given to adequately sample representative areas. Given adequate sampling, this problem, however, is best resolved after the field survey is completed and various descriptions have been tried. Ideally, all species present in the sample site at the time of sampling should be recorded. As a minimum, the dominant species in each stratum should be recorded.

Species codes A code using the first two letters of the genus and the first three letters of the species is more convenient than writing names in full. For the few species with the same code, replace the last letter with a number. Some people use four letters for genus and four letters for species to avoid sequences that may be confusing; others use a ‘pick list’ to record full scientific names. Examples of floristic codes are:

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EUPOP

Eucalyptus populnea (dominant species in dominant stratum)

ERMIT

Eremophila mitchellii (dominant species in mid-stratum)

BODEC

Bothriochloa decipiens (dominant species in lower stratum)

ERGLA

Eremophila glabra

ERGL2

Eremocitrus glauca

Floristics Floristics is the list of plant species found at a sample site. Record the name of each species, native and non-native, unless a list of what to include or exclude has been defined for your project. It is preferable to use the full scientific name to avoid ambiguities and to make it easier to combine datasets. If using ad hoc species names, ensure that voucher specimens are collected and records are updated with scientific names. Each State and Territory maintains comprehensive lists of plant species. The major State, Territory and national herbaria have established the Australian Plant Census to produce a national list of scientific names with major synonyms. This Census will contain the names used in Australia’s Virtual Herbarium (2007). Comprehensive species lists prepared by State and Territory environment departments or herbaria are available for some vegetation types and parts of Australia. These lists should be used as part of the field recording proforma to speed recording and to direct attention to unusual species records requiring detailed notes and possibly voucher specimens or photographs. Prepare this list as an initial checklist. Flora of Australia (Commonwealth of Australia 2007) is available online, as are State-level identification tools. Interactive multi-entry digital keys to major plant groups are available and more can be expected. Specimens should be collected to provide reference material to verify or confirm species identifications, or as tools to help ensure consistent identifications between workers and over time. It is not always necessary to collect plant specimens, especially at the formation and structural formation levels. However, good field-based floristic work is based on the following practices:

97

Tree

w1.0

98

Tree: planted/ cultivated (non-food)

Tree: planted/ cultivated (food)

Tree: 2–50 planted/ cultivated (landscaping)

Woody plant (indeterminate tree or shrub)

Mallee (tree or shrub)

w1.2

w1.3

w1.4

w2.0

w2.1 0.1–30

0.1–10

2–50

2–50

Tree: rainforest

w1.1 2–50

2–50

Growth form of dominant Height stratumd range (m)

Closed X mallee

Closed X woody plants

Closed X trees

Closed X trees

Closed X trees

Closed X trees

Closed X trees

M Mid-dense

D Closed or dense

Cover code & name

Growth form codec

0–0.25

<0

Crown separation ratio

Mid-dense X mallee

V Very sparse

1–20

20–0.25

10–0.2

I Isolated plants

>20

<0.25

<0.2

Sparse X trees

Sparse X trees

Sparse X trees

Sparse X trees

Sparse X trees

Sparse X mallee

Very sparse X mallee

Very sparse X woody plants

Very sparse X trees

Very sparse X trees

Very sparse X trees

Very sparse X trees

Very sparse X trees

Isolated X mallee

Isolated X woody plants

Isolated X trees

Isolated X trees

Isolated X trees

Isolated X trees

Isolated X trees

Broad floristic formation classese

S Sparse or open

0.25–1

50–20

30–10

Cover characteristics

Mid-dense X Sparse X woody plants woody plants

Mid-dense X trees

Mid-dense X trees

Mid-dense X trees

Mid-dense X trees

Mid-dense X trees

80–50

>80

Crown cover (%)

70–30

100–70

Foliage cover (%)

Table 21 Broad floristic formations (Level 3) a

Isolated clumps of X mallee

Isolated clumps of X woody plants

Isolated clumps of X trees

Isolated clumps of X trees

Isolated clumps of X trees

Isolated clumps of X trees

Isolated clumps of X trees

L Isolated clumps

>20

<0.25

<0.2

X mallee

X woody plants

X trees

X trees

X trees

X trees

X trees

E Emergents

>3

<5b

<3b

Australian Soil and Land Survey Field Handbook

Chenopod shrub

Samphire shrub

Shrub: planted/ cultivated (food)

Shrub: planted/ cultivated (non-food)

w3.2

w3.3

w3.4

w3.5

99

Hummock grass

Tussock grass <5

Grass: planted/ cultivated

Grass: planted/ cultivated (pasture)

Grass: planted/ cultivated (cereals)

g2.0

g3.0

g4.0

g4.1

g4.2 <5

<4

<3

<2

Grass

g1.0 0.01–5

<10

<8

<3

<3

Heath or <8 kwongan or wallum shrub

w3.1

<20

Shrub

w3.0

Closed X cereals

Closed X pasture

Closed X grasses

Closed X tussock grasses

Closed X hummock grasses

Closed X grasses

Closed X industrial shrubs

Closed X food shrubs

Closed X samphire shrubs

Closed X chenopod shrubs

Closed X heath shrubs

Closed X shrubs

Mid-dense X cereals

Mid-dense X pasture

Mid-dense X grasses

Mid-dense X tussock grasses

Mid-dense X hummock grasses

Mid-dense X grasses

Mid-dense X industrial shrubs

Mid-dense X food shrubs

Mid-dense X samphire shrubs

Mid-dense X chenopod shrubs

Mid-dense X heath shrubs

Mid-dense X shrubs

Sparse X cereals

Sparse X pasture

Sparse X grasses

Sparse X tussock grasses

Sparse X hummock grasses

Sparse X grasses

Sparse X industrial shrubs

Sparse X food shrubs

Sparse X samphire shrubs

Sparse X chenopod shrubs

Sparse X heath shrubs

Sparse X shrubs Isolated X heath shrubs

Isolated X shrubs

Very sparse X cereals

Very sparse X pasture

Very sparse X grasses

Very sparse X tussock grasses

Very sparse X hummock grasses

Very sparse X grasses

Very sparse X industrial shrubs

Very sparse X food shrubs

Very sparse X samphire shrubs

Isolated X cereals

Isolated X pasture

Isolated X grasses

Isolated X tussock grasses

Isolated X hummock grasses

Isolated X grasses

Isolated X industrial shrubs

Isolated X food shrubs

Isolated X samphire shrubs

Very sparse Isolated X X chenopod chenopod shrubs shrubs

Very sparse X heath shrubs

Very sparse X shrubs

X samphire shrubs

X chenopod shrubs

X heath shrubs

X shrubs

Isolated clumps of X cereals

Isolated clumps of X pasture

Isolated clumps of X grasses

Isolated clumps of X tussock grasses

Isolated clumps of X hummock grasses

Isolated clumps of X grasses

X cereals

X pasture

X grasses

X tussock grasses

X hummock grasses

X grasses

Isolated X X industrial industrial shrubs shrubs

Isolated clumps X food of X food shrubs shrubs

Isolated clumps of X samphire shrubs

Isolated clumps of X chenopod shrubs

Isolated clumps of X heath shrubs

Isolated clumps of X shrubs

Vegetation

Grass: planted/ cultivated (other industrial)

Sedge

Rush

Forb

Herb

Herb: planted/ cultivated (perennial, non-food)

Herb: planted/ cultivated (annual, non-food)

Herb: planted/ cultivated (perennial, food)

Herb: planted/ cultivated (annual, food)

g4.3

g5.0

g6.0

h1.0

h2.0

h2.1

h2.2

100

h2.3

h2.4 <2

<2

<2

<2

<2

<2

<3

<3

<3

Growth form of dominant Height stratumd range (m)

Growth form codec

Table 21 (cont.)

Closed X herbs

Closed X herbs

Closed X herbs

Closed X herbs

Closed X herbs

Closed X forbs

Closed X rushes

Closed X sedges

Closed X grasses

Mid-dense X herbs

Mid-dense X herbs

Mid-dense X herbs

Mid-dense X herbs

Mid-dense X herbs

Mid-dense X forbs

Mid-dense X rushes

Mid-dense X sedges

Mid-dense X grasses

Sparse X herbs

Sparse X herbs

Sparse X herbs

Sparse X herbs

Sparse X herbs

Sparse X forbs

Sparse X rushes

Sparse X sedges

Sparse X grasses

Very sparse X herbs

Very sparse X herbs

Very sparse X herbs

Very sparse X herbs

Very sparse X herbs

Very sparse X forbs

Very sparse X rushes

Very sparse X sedges

Very sparse X grasses

Isolated X herbs

Isolated X herbs

Isolated X herbs

Isolated X herbs

Isolated X herbs

Isolated X forbs

Isolated X rushes

Isolated X sedges

Isolated X grasses

Broad floristic formation classese

Isolated clumps of X herbs

Isolated clumps of X herbs

Isolated clumps of X herbs

Isolated clumps of X herbs

Isolated clumps of X herbs

Isolated clumps of X forbs

Isolated clumps of X rushes

Isolated clumps of X sedges

Isolated clumps of X grasses

X herbs

X herbs

X herbs

X herbs

X herbs

X forbs

X rushes

X sedges

X grasses

Australian Soil and Land Survey Field Handbook

Seagrass: marine

a2.0

101 <30

Record thick-ness of layer

<2

<2

0.5–30

<0.05

<5

<2

<2

Bare groundf

Closed X marine algae

Closed X algae

Closed X seagrasses

Closed X aquatic plants

Closed X vines

Closed X crusts

Closed X lichens

Closed X bryophytes

Closed X ferns

Sparse X vines

Sparse X crusts

Sparse X lichens

Sparse X bryophytes

Sparse X ferns

Mid-dense X marine algae

Mid-dense X algae

Mid-dense X seagrasses

Sparse X marine algae

Sparse X algae

Sparse X seagrasses

Mid-dense X Sparse X aquatic plants aquatic plants

Mid-dense X vines

Mid-dense X crusts

Mid-dense X lichens

Mid-dense X bryophytes

Mid-dense X ferns

Isolated X aquatic plants

Isolated X vines

Isolated X crusts

Isolated X lichens

Isolated X bryophytes

Isolated X ferns

Very sparse X marine algae

Very sparse X algae

Isolated X marine algae

Isolated X algae

Very sparse Isolated X X seagrasses seagrasses

Very sparse X aquatic plants

Very sparse X vines

Very sparse X crusts

Very sparse X lichens

Very sparse X bryophytes

Very sparse X ferns

Isolated clumps of X marine algae

Isolated clumps of X algae

Isolated clumps of X seagrasses

Isolated clumps of X aquatic plants

Isolated clumps of X vines

Isolated clumps of X crusts

Isolated clumps of X lichens

Isolated clumps of X bryophytes

Isolated clumps of X ferns

X marine algae

X algae

X seagrasses

X aquatic plants

X vines

X crusts

X lichens

X bryophytes

X ferns

a For consistency in naming broad floristic formation classes in this table, two changes to Walker and Hopkins (1990) have occurred: the terms ‘forest’ and ‘woodland’ have been replaced with ‘trees’, and the suffix ‘land’ has been removed. b For emergents, ‘<3’ means ‘up to 3% of total foliage cover’ and ‘<5’ means ‘up to 5% of the total crown cover’. c Cells shaded grey in this column are woody life forms (w) while the unshaded cells are non-woody life forms ( nw). d See page 88 for definitions of growth forms. e In each class name, replace the ‘X’ with the taxonomic name from either the dominant genus or genus group making up the dominant stratum. Not all classes require a separate taxonomic name (e.g. mid-dense mallee). In other cases the ‘X’ name is optional, for example sparse chenopod shrubs versus sparse Atriplex chenopod shrubs or sparse Atriplex shrubs. f The classes for bare surface are deliberately not given a name but can be coded.

Bare surface

Aquatic higher plants

a1.0

b1.0

Vine

v1.0

Algae: marine

Surface crusts

c1.0

a4.0

Lichen

l1.0

Algae: fresh or brackish

Bryophyte

m1.0

a3.0

Fern (excluding tree ferns)

f1.0

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Australian Soil and Land Survey Field Handbook

s Ensure that appropriate collecting permits and/or permissions are obtained before collecting. Each State/Territory/Commonwealth has its own regulations and procedures. In many instances these can be accessed from web pages of the relevant authority. s Know what constitutes an adequate specimen for the various types of plants you will encounter. Contact your local or State/Territory herbarium, or an experienced field collector, for advice if need be. Guidelines are also available from various websites. s Know what rare flora may be encountered, how to identify it and what to do if any are found. There may be limits on collecting such material. Photographs may suffice as records for rare flora. s Record in a field notebook, especially maintained for plant collections, the basic information for voucher specimens: plant name, location where collected (geocoordinates, distance/direction from known geographic feature), date, collector and collector’s number, habitat (e.g. soil, vegetation type), plant height, phenological state (e.g. flowering, fruiting, leafing, dormant, colours of plant parts). s Tag each specimen, recording the collector’s name/initials and field number, which should be unique to the collector or the project and which will also be recorded on the field data sheets. s Preserve the plants by drying in a plant press. Some types of plants may need special treatment (e.g. mosses, lichens, fungi, algae, aquatic plants, succulents, very large plants/leaves). s If using field names and ID numbers, ensure subsequent updating of records when formal identification is complete. s Where possible, arrange to deposit voucher specimens in an appropriate herbarium. Voucher collections can be of two types. The first type is a reference set for field workers. This collection may be taken into the field and consists only of snippets of relevant plant parts, or scanned and printed images of such plants, to aid in field identification. The second type of voucher collection is deposited in a herbarium; higher collecting and recording standards may then apply.

EXAMPLES OF STANDARD CLASSIFICATION As seen in Table 14, the first step in a standard classification is identifying the strata. The attributes for each stratum are then measured in the field as described earlier in this chapter; each level of classification requires the 102

Vegetation

attributes as listed in Table 14. Once these data are gathered, the vegetation type in each stratum can be named and coded as shown in Figure 8. Multiple strata can be named and coded following the sequence: upper stratum height/ cover/growth form; mid-stratum or strata height/cover/growth form; ground stratum height/cover/growth form. For the example shown in Figure 8, a hypothetical site with four strata and emergent trees is used. The full names and codes at four different levels of classification are as follows: Formation (Level 1) Name:

‘Mid-dense woody plants’

Code:

Mw

Structural formation (Level 2) Name:

‘Emergent very tall trees with very tall mid-dense trees’

Code:

E8w1.0 /8Mw1.0

Broad floristic formation (Level 3) Name:

‘Emergent very tall Angophora with very tall mid-dense Eucalyptus trees’

Code:

E8Angophoraw1.0 /8MEucalyptusw1.0

Broad floristic subformation (Level 4) Name:

‘Emergent very tall Angophora trees over very tall mid-dense Eucalyptus trees with tall sparse Eucalyptus tree understorey over dwarf very sparse Eremophila shrubs with a tall sparse Bothriochloa tussock grass ground stratum’

Code:

E8Angophoraw1.0 /8MEucalyptusw1.0 /7SEucalyptusw1.0 /4VEremophilaw3.0 /3SBothriochloag3.0

Further detail may be added. For example, some vegetation types such as wetlands or rainforests may require additional attributes, or the surveyor might wish to assess the growth stage or condition of the vegetation.

WETLANDS Wetlands are defined by the Ramsar Convention (Anon. 1994) as ‘… areas of marsh, fen, peatland or water, whether natural or artificial, permanent or 103

Australian Soil and Land Survey Field Handbook

E

E

Emergent (E)

A Upper (U)

B Mid-stratum 1 (M1)

C D

Mid-stratum 2 (M2) Ground (G)

Figure 8 A hypothetical site with four strata (top heights A, B, C and D) and emergent trees (top height E). Refer to text (page 103) and the table opposite for the full codes and names at four levels of classification for this example.

temporary, with water that is static or flowing, fresh, brackish or salt, including areas of marine water the depth of which at low tide does not exceed six metres’. Some wetland vegetation types overlap with dryland vegetation types while other types are unique. The presence or degree of inundation may not always be discernable at the time of sampling. Ephemeral and periodic wetlands pose recording issues similar to those of ephemeral annual dryland plants. Because changes that affect vegetation structure, cover, height and floristic composition are much faster than for most dryland sites, special sampling programs are required to record the essential aspects of wetlands. If the wetland is ephemeral, intermittent or fluctuating, field workers may not be able to identify the plants’ growth form at the time of sampling. In such cases, record the plants as they are seen and indicate whether the site appears to be a wetland and whether the water level appears to be changing. Record the type of wetland as per those listed later in this chapter in ‘Aquatic and wetland types’ and the dominant growth forms as per Table 22.

104

Tree (w1.0)

Growth formc (code)

105 Eucalyptus 8MEucalyptusw1.0

8MEucalyptusw1.0

Emergent very tall trees Angophora E8Angophoraw1.0

E8Angophoraw1.0

Descriptionc

Broad floristic formation (Level 3) full code

Broad floristic subformation (Level 4) full code

a b c d

See ‘Life form’, page 80. See Table 17 and Table 18. See ‘Growth form’ (page 88) and Table 21. See Table 20.

Genus or species

Very tall mid-dense trees

28 m (very tall, 8)

Heightd (name, code)

21 m (very tall, 8)

Tree (w1.0)

67% 0.1 (mid-dense, M)

3% 4.0 (emergent, E)

Woody plants (w)

Dominant stratum (U)

A

Crown separation ratiob (name, code)

Woody plants (w)

Emergent (E)

E

Crown coverb

Life forma (code)

Stratum name (code)

Top height

Figure 8 (cont.)

7SEucalyptusw1.0

Eucalyptus

Tall sparse trees

11 m (tall, 7)

Tree (w1.0)

0.9 (sparse, S)

22%

Woody plants (w)

Mid-stratum 1 (M1)

B

4VEremophilaw3.0

Eremophila

Dwarf very sparse shrubs

2 m (dwarf, 4)

Shrub (w3.0)

1.5 (very sparse, V)

13%

Woody plants (w)

Mid-stratum 2 (M2)

C

3SBothriochloag3.0

Bothriochloa

Tall sparse tussock grasses

0.7 m (tall, 3)

Tussock grass (g3.0)

0.8 (sparse, S)

25%

Non-woody plants (nw)

Ground stratum (G)

D

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Australian Soil and Land Survey Field Handbook

Table 22 Wetland growth forms Code

Type

Notes

1

Emergent, permanent

Woody or herbaceous, not ephemeral

2

Emergent, ephemeral

Herbaceous, ephemeral

3

Floating stems with leaves at the surface but roots in substrate

Herbaceous, leaves at surface

4

Floating mats

Predominantly herbaceous (e.g. grass mats not attached to substrate)

5

Fully submerged with roots attached to substrate

Herbaceous with whole plant below surface; in some cases flowers may be emergent

6

Fully submerged, floating

Unattached plant, submerged (e.g. freefloating herbs or algae)

Wetland-specific sampling methods may be found in Anderson (1999) and Brock and Casanova (2000). Use site observations (especially at planned times of year or relative to drought–non-drought cycles), aerial photographs and maps. Brock and Casanova (2000) provide detailed methods for sampling in wetlands. The method presented here allows the major types of wetlands to be identified. Additional attributes would be needed for detailed analysis of wetlands.

Aquatic and wetland types The 40 aquatic and wetland types listed here are taken from the Directory of important wetlands in Australia (Commonwealth of Australia 2001). The definition of wetland is consistent with that adopted by the Ramsar Convention, Article 1.1 (Anon. 1994). Marine vegetation below 6 m depth is not covered in this manual. A – Marine and coastal zone wetlands 1

Marine waters – permanent shallow waters less than 6 m deep at low tide; includes sea bays, straits

2

Subtidal aquatic beds; includes kelp beds, seagrasses, tropical marine meadows

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Vegetation

3

Coral reefs

4

Rocky marine shores; includes rocky offshore islands, sea cliffs

5

Sand, shingle or pebble beaches, sand bars, spits, sandy islets

6

Estuarine waters; includes permanent waters of estuaries and estuarine systems of deltas

7

Intertidal mud, sand or salt flats

8

Intertidal marshes; includes salt marshes, salt meadows, raised salt marshes, tidal brackish and freshwater marshes

9

Intertidal forested wetlands; includes mangrove swamps, nipa swamps, tidal freshwater swamp forests

10

Brackish to saline lagoons and marshes with one or more relatively narrow connections with the sea

11

Freshwater lagoons and marshes in the coastal zone

12

Non-tidal freshwater forested wetlands

B – Inland wetlands 13

Permanent rivers and streams; includes waterfalls

14

Seasonal and irregular rivers and streams

15

Inland deltas (permanent)

16

Riverine floodplains; includes seasonally flooded grassland, savanna and palm savanna; river flats; flooded river basins

17

Permanent freshwater lakes (>8 ha); includes large oxbow lakes

18

Seasonal/intermittent freshwater lakes (>8 ha), floodplain lakes

19

Permanent saline/brackish lakes

20

Seasonal/intermittent saline lakes

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Australian Soil and Land Survey Field Handbook

21

Permanent freshwater ponds (<8 ha), marshes and swamps on inorganic soils; emergent vegetation is waterlogged for at least most of the growing season

22

Seasonal/intermittent freshwater ponds and marshes on inorganic soils; includes billabongs, sloughs, potholes, seasonally flooded meadows, sedge marshes

23

Permanent saline/brackish marshes

24

Seasonal saline marshes

25

Shrub swamps; includes shrub-dominated freshwater marsh, shrub carr, alder thicket on inorganic soils

26

Freshwater swamp forest – seasonally flooded forest or wooded swamps on inorganic soils

27

Peatlands; includes forest, shrub or open bogs

28

Alpine and tundra wetlands; includes alpine meadows, tundra pools, temporary waters from snow melt

29

Freshwater springs, oases and rock pools

30

Geothermal wetlands

31

Inland subterranean karst wetlands

C – Human-made wetlands 32

Water storage areas; includes reservoirs, barrages, hydroelectric dams, impoundments (generally >8 ha)

33

Ponds; includes farm and stock ponds, small tanks (generally <8 ha)

34

Aquaculture ponds; includes fish ponds, shrimp ponds

35

Salt exploitation; includes salt pans, salines

36

Excavations; includes gravel pits, borrow pits, mining pools

37

Wastewater treatment, sewage farms, settling ponds, oxidation basins

108

Vegetation

38

Irrigated land and irrigation channels; includes rice fields, canals, ditches

39

Seasonally flooded arable land, farm land

40

Canals

RAINFOREST In Australia, there are patches of rainforest across the tropical north, down the east coast, and in Tasmania. They are usually easy to distinguish from adjacent forests, which are typically dominated by Eucalyptus and related genera. Rainforests tend to have closed canopies that are usually dark green and easily distinguished from the generally greyish and reddish-green canopies of surrounding forests. The ‘dry scrubs’ of south-east Queensland are closely related to rainforests and are classified as such. The ‘dry’ rainforests in the Northern Territory, Western Australia and parts of Queensland, as well as the temperate rainforests in south-eastern mainland Australia, are usually classified using the standard methods (see ‘Overview of the classification’, page 75). Due to their structural complexity, however, it may not be practical to classify the wet tropical and subtropical rainforests of Australia using the attributes and methods used for other vegetation types. The cool temperate rainforests of Tasmania can also be complex in structure. These two varieties of rainforests may be sampled using either the standard classification, or methods supplemented with extra structural attributes to fully reflect the additional complexity (Table 23). The rest of this section deals separately with these two special cases.

Tropical and subtropical rainforests Australian tropical rainforests are situated above 18° latitude whereas subtropical rainforests are between about 18° and 33° latitudes.

Complexity Tropical and subtropical rainforests of eastern Australia are classified as simple, simple–complex or complex depending on their structural complexity.

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Australian Soil and Land Survey Field Handbook

Table 23 Additional attributes used to classify two special cases of rainforest Wet tropical or subtropical rainforest

Tasmanian cool temperate rainforest

For dominant stratum only, record: 1. Complexity 2. Leaf size 3. Species 4. Indicator growth form 5. Crown cover (crown separation) and height 6. Emergents (if any) 7. Sclerophyll species present

Identify dominant stratum and any other strata present. For at least the dominant stratum and understorey strata, record: 1. Dominant species 2. Type of crown 3. Height 4. Species present (at least the dominants)

S

Simple

Forests showing most or all of the following properties: s the tendency for one or a few species to dominate the canopy (e.g. coachwood or myrtle beech) s a reduced number of structural features (e.g. plant buttresses absent, or most stems unbuttressed or with star buttresses) s a tendency for one or two growth forms to be more conspicuous (e.g. trunks not usually obscured by climbing plants and epiphytes, but when they do one growth form usually dominates; or understorey layers may have a conspicuous growth form such as a tree fern layer, ground fern layer, shrub or palm layer) s the stem diameters of the canopy trees are usually uniform in size s discrete strata (e.g. a tree fern layer, an understorey tree layer or shrubs).

X

Simple– complex

Forests with features of simple and complex forests. Use this category if in doubt or if the vegetation does not possess at least four out of the five properties listed for the other categories.

110

Vegetation

C

Complex

Forests characteristically showing all or most of the following properties: s the tallest stratum, excluding emergent, has many species s a large range of structural features (e.g. plant buttresses, spur buttresses, unbuttressed stems, compound leaves, simple leaves, lobed and deeply divided leaves, strap-like leaves) s a large range of growth forms, none of which tends to dominate (e.g. trunk bases usually obscured by climbing pandans, palms, ferns and aroids; robust and slender lianes are present; complex understorey consisting of shrubs, seedlings of larger trees, palms, gingers, pandans and ferns) s the vegetation is not usually arranged into distinguishable, discrete strata s the stem diameters of the tallest non-emergent trees are usually uneven in size.

Leaf size Leaf size classes for classifying wet tropical and subtropical rainforests are based on the sizes of the leaves of the tallest stratum trees. Precise calculation of leaf area is not required. Record the length and width of a representative sample of canopy leaves (leaves that are exposed to the full sun during their early development, as occurs at the top of the canopy). Numerical values and a field sheet of actual leaf sizes are given in Figure 9; precision greater than the classes shown is not required. The forest is described using one of nine terms depending on the proportion of individual trees in the tallest stratum with leaves in each of the leaf size categories (Table 24). Leaf size is assessed by examining leaves from 10 adjacent canopy trees in the sample plot. The following rules should be used: s Where the average leaf size of a tree appears to be intermediate between size classes (e.g. the leaf length of a lanceolate leaf is about 75 mm), the larger size class should be nominated.

111

mm

150 140 130 120 110

100 90 80 70

less than

60

less than

50

less than

40

between c and 2d

a Nanophyll b Microphyll c Notophyll d Mesophyll between 2x d and 8x the size of the rectangle

30 20

Macrophyll 10

0

Leaf size category Macrophyll Mesophyll Notophyll Microphyll Nanophyll

Leaf area (mm 2)

Approx. length of lanceolate leaf (mm)

Approx. length of cordate or peltate leaf (mm)

>18225 4500 −18225 2025 − 4500 225 −2025 25 −225

>250 125 −250 75 −125 25 −75 <25

>160 80 −160 60 − 80 20 − 60 <20

Figure 9 Actual leaf size categories for rainforest trees. From Walker and Hopkins (1990) based on Raunkiaer (1934) and Webb (1959).

Vegetation

Table 24 Terms for describing leaf size in the tallest stratum of tropical or subtropical rainforest Term describing leaf size of forest stand

Number of individual trees (maximum 10) with specified leaf sizes

Percentage of individuals in tallest stratum with specified leaf size

1

Macrophyll

>5 macro

>50% macro

2

Macrophyll–mesophyll

3–5 macro and 1–4 meso

30–50% macro and 10–40% meso

3

Mesophyll

>5 meso

>50% meso

4

Mesophyll–notophyll

3–5 meso and 1–4 noto

30–50% meso and 10–40% noto

5

Notophyll

>5 noto

>50% noto

6

Notophyll–microphyll

3–5 noto and 1–4 micro

30–50% noto and 10–40% micro

7

Microphyll

>5 micro

>50% micro

8

Microphyll–nanophyll

3–5 micro and 1–4 nano

30–50% micro and 10–40% nano

9

Nanophyll

>5 nano

>50% nano

s Only leaves that are exposed to the sun should be considered. Because these leaves are usually at the top of a tree, a shotgun or catapult may be necessary. An alternative is to locate recently fallen leaves on the ground. s Leaves of palms, aroids and vines should not be considered. s The size of the leaflet of a compound leaf should be considered. Two possible, but unlikely, combinations of leaf sizes cannot be described adequately by this scheme. If all leaf sizes are represented equally (20% each), the forest should be described as notophyll. If any three size classes are represented equally (e.g. 30% macrophyll, 30% mesophyll and 30% notophyll), the intermediate leaf size term mesophyll should be selected.

Species The type of rainforest is named after the most abundant species of the dominant stratum, using the following system. M

Mixed

No one or two species combined make 50% or more of the crown cover in the tallest stratum.

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Australian Soil and Land Survey Field Handbook

S

One or two species description

The one or two species described constitute 50% or more of the crown cover of the tallest stratum. Common, generic or specific names can be used (e.g. coachwood–crabapple; Ceratopetalum– Schizomeria; Ceratopetalum apetalum–Schizomeria ovata). Use species name abbreviations for coding (e.g. CEAPE.SCOVA) except for fan or feather palms, which should not be used as common names because they are used to denote structural features (see ‘Indicator growth forms’). Include sclerophyll species if they constitute 50% or more of the crown cover of the tallest stratum.

X

Mixed plus one species

Although no species or two species combined make up 50% of the crown cover of the dominant stratum, one species (the one species nominated) is conspicuously abundant. As above, common, generic or specific names can be used except for feather or fan palms (e.g. Mixed Booyong; Mixed Argyrodendron; Mixed Argyrodendron trifoliolatum or ARTRI). This floristic term can be used to nominate species of particular indicator value to the user.

Many rainforest species occur in clusters of five or six trees. Care should be taken to ensure that the species of the tallest stratum are found over a much wider area than a few trees if the species qualifications are used.

Indicator growth forms Many of the simple rainforests and some of the complex and simple–complex rainforests develop strata dominated by particular growth forms. These growth forms are illustrated in Webb et al. (1976). Record the growth form name or code as follows. 1

Moss

Forests in which mosses and lichens almost completely replace vascular epiphytes and vines on the trunks and in the crowns.

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Vegetation

2

Fern

Tree ferns form a dense/closed (80–100% crown cover) and discrete understorey stratum.

3

Fan palm

Forests in which fan palms (palms with branches spreading out in a fan shape, e.g. Licuala or Livistona) form a dense/closed stratum (80–100% crown cover) below the tallest stratum. If they form a closed stratum within the upper stratum, it would be registered as the third example in the section ‘Coding tropical or subtropical rainforests’.

4

Feather palm

Forests in which feather palms (palms, e.g. coconut palms, with narrow long leaves that appear feather-like from a distance) form a dense/closed (80–100% crown cover) understorey stratum.

5

Vine

Forests in which vines or twining or scrambling plants drape at least 60% of the tallest stratum and emergent trees.

6

None

If none of the five growth forms above reaches the required level of dominance nominated, the description should record ‘no dominant indicator growth form’.

These terms are inserted before or within the structural formation class: for example, ‘tall sparse fern forest’; ‘very tall closed fan palm forest’; ‘low closed vine shrubland’; ‘tall closed feather palm forest’.

Crown cover and height Cover and height classes have been defined previously (see Tables 17 and 20).

Emergents Emergents are plants, usually trees, that are clearly above the dominant stratum and whose crown cover is less than 5% of the total crown cover (see ‘Emergents’, page 94). Trees that have a greater crown cover and project above a rainforest are coded and named using the standard classification (see Tables 17, 20 and 21).

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Australian Soil and Land Survey Field Handbook

Record the genus and, if possible, species of emergents followed by the word ‘emergents’. For example: ‘with hoop pine emergents’; ‘with Araucaria emergents’; ‘with Eucalyptus emergents’. If no emergents are present, no qualifying character is nominated. E

Common sclerophyllous emergents over rainforest include species of Eucalyptus, Corymbia, Acacia, Syncarpia, Casuarina, Lophostemon and Melaleuca.

A

Common non-sclerophyllous rainforest emergents include Agathis, Podocarpus, Araucaria, Flindersia and Erythrina.

Emergents are usually identified visually by experienced workers, but are confirmed by actual records of cover. The crown cover of emergents may exceed 5% of the total crown cover in some instances. For example, in some forest stands Araucaria trees emerge above a closed rainforest canopy with their crown cover exceeding 5% of the total crown cover in some places. These patches should not be classified as separate vegetation types.

Sclerophyll species in dominant stratum Record the presence of any sclerophyll genera. Common sclerophyll genera are Eucalyptus, Corymbia, Acacia, Syncarpia, Casuarina, Allocasuarina, Lophostemon, Tristaniopsis and Melaleuca. In this rainforest schema, Agathis, Podocarpus and Araucaria are not classed as sclerophyll. S

If sclerophyll species (defined above) are present in the dominant stratum, these should be recorded by adding the qualifying term ‘and sclerophylls’. If the sclerophylls can be identified, ‘sclerophyll’ should be replaced by the specific, generic or common name (e.g. ‘and wattles’). Where sclerophyll species are 50% of the crown cover of the canopy, this will have been recorded and need not be repeated.

Coding tropical/subtropical rainforests Table 25 summarises codes for the tropical/subtropical rainforest classification. Examples are shown in Table 26.

Tasmanian rainforests Tasmanian rainforests can be sampled using the standard classification in the previous chapters of these guidelines. However, a method widely in use 116

S Simple X Simple– complex C Complex

Complexity

8 Microphyll–nanophyll 9 Nanophyll

6 Notophyll–microphyll 7 Microphyll

4 Mesophyll–notophyll 5 Notophyll

1 Macrophyll 2 Macrophyll–mesophyll 3 Mesophyll

Leaf size of trees in dominant stratum M Mixed S Described by one or two species X Mixed plus one species description

Species of trees in dominant stratum

Core attributes

1 Moss 2 Fern 3 Fan palm 4 Feather palm 5 Vine 6 None

Indicator growth form See Tables 17 and 20

Crown cover and height

Table 25 Attributes and codes used to classify tropical or subtropical rainforests

With (species name) emergent E or A E Sclerophyll emergents A Non-sclerophyll emergents

Emergents

S

With (or ‘and’) sclerophylls (or species name)

Sclerophyll species in dominant stratum

Qualifying attributes

Vegetation

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Table 26 Examples to illustrate coding for both the standard and tropical or subtropical rainforest classification Tropical/subtropical rainforest classification Notes

Standard classificationa

Description

Code

Code (Level 2)

Complex mesophyll mixed tall closed forest

C3M6

Simple notophyll very tall closed coachwood forest with Lophostemon confertus emergents

S5S6

E for emergents is coded with structure

E8w1.1 /8Dw1.1

Simple notophyll tall closed mixed fan palm forest and Acacia

S5M3S

The last S is for sclerophylls in upper stratum

7Dw1.1

Simple notophyll tall closed Schizomeria forest with Syncarpia emergents and eucalypts

S5S6S

The last S is for sclerophylls in upper stratum

E7w1.1 /7Dw1.1

Complex mesophyll mixed extremely tall closed black-bean forest

C3M6

Simple macrophyll–mesophyll low closed Macaranga– Trichospermum forest with Acacia emergents (young secondary forest)

S2S6S

Mixture of Eucalyptus regnans giant very sparse trees above a simple microphyll very tall closed Atherosperma moschatum forest

S7S6

7Dw1.1

9Dw1.1

The last S is for sclerophylls in upper stratum

E5w1.1 /5Dw1.1

10Vw1.1 /8Dw1.1

a This is the standard classification as summarised in ‘Examples of standard classification’ (page 102) and Figure 8. Rainforests may be classified using either this standard classification alone, or using the more specialised tropical/subtropical rainforest classification shown in the first three columns of this table.

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119

Thamnic

Implicate

T

I

Myrtle beech

Myrtle beech

Low forests dominated by Athrotaxis cupressoides and less commonly by A. selaginoides. The canopy is usually open with widely spaced trees, though dense clumps may occur. The understorey is dominated by low shrubs, grasses or mosses (Sphagnum). Shrub heights range from half to two-thirds the height of the canopy. Woody species diversity is relatively high.

Low forest, with broken uneven canopies. Dominance is usually shared by several species including Nothofagus cunninghamii, N. gunnii (rarely), Eucryphia lucida, E. milliganii, Phyllocladus aspelniifolius, Athrotaxis selaginoides, Lagerostrobus franklinii, Diselma archeri, Leptospermum nitidum, L. glaucescens, L. scoparium, L. lanigerum, Melaleuca squarrosa and Acacia mucronata. The understorey is tangled and mostly forms a continuous layer from the ground to the canopy; emergents may be present. Species diversity is relatively high for trees and shrubs.

Medium height forest dominated by two to five species, mostly of: Nothofagus cunninghamii, N. gunnii (rarely), Eucryphia lucida, E. milliganii, Atherosperma moschatum, Phyllocladus aspelniifolius, Lagerostrobus franklinii and Athrotaxis selaginoides. Trees well formed; a distinct shrub layer present.

Medium to tall forest dominated by Nothofagus cunninghamii and/or Atherosperma moschatum. Trees well formed and widely spaced; understorey open, shady and park-like. Low diversity of woody species, which are sparse and inconspicuous in the understorey of most communities.

Description

5Sw1.1 /4Mw3.0 /0Dm1.0

(E) /5Mw1.1 /4Sw3.0

6Mw1.1 /5Mw3.0

6–7Dw1.1

Code (Level 2)

Standard classificationa

a This is the standard classification as summarised in ‘Examples of standard classification’ (page 102) and Figure 8. Rainforests may be classified using either this standard classification alone, or using the more specialised Tasmanian rainforest classification shown in the first four columns of this table.

M

Callidendrous

C

Myrtle beech

Montane

Suballiance

Code

Alliance

Tasmanian rainforest classification

Table 27 Distinguishing characteristics of Tasmanian rainforests

Vegetation

Australian Soil and Land Survey Field Handbook

in Tasmania classifies rainforest based on the work of Jarman et al. (1991) and Reid et al. (1999). This system uses a combination of floristics and structure that can be coded into the NVIS vegetation hierarchy at Level IV (Table 16). The system divides Tasmanian rainforests into two alliances: myrtle beech and montane forest. Myrtle beech is the most widespread and, although recognised as comprising a continuum, it is divided into three suballiances: callidendrous, thamnic and implicate. The characteristics of these four units are presented in Table 27.

GROWTH STAGE The growth stage of vegetation is its phase in the life cycle. Accurately assessing growth stage can be difficult in unfamiliar vegetation. Growth stage is better known for trees, and less well-known for vegetation dominated by non-woody plants. Vegetation appearance can be affected by condition (see ‘Condition’) as well as growth stage. It may not be possible to distinguish the effects of age from responses due to stress caused by environmental factors such as pests, diseases or land use. Walk through the site and immediate surrounding area, looking for signs that indicate the history of the development of the vegetation. Record the code from Table 28 as well as the features on which the assessed stage is based. Where the vegetation is dominated by trees, especially eucalypts in southeastern and south-western parts of Australia, the signs of ageing are evident and well documented (Jacobs 1955; Eyre et al. 2002; Figure 10a). Growth stages of trees in sparse vegetation (‘woodland’ trees) are similar to those in mid-dense and closed vegetation (‘forest’ trees), but the overall tree-form is shorter and wider (Figure 10b). There is little documentation of growth stages for shrubs. Lange and Purdie (1976) indicate the general cycle of ageing of western myall (Acacia papyrocarpa) shrubs in inland Australia, which can be used as guide for other shrubs (Figure 10c).

CONDITION Condition refers to the state of vegetation relative to some specified benchmark. A benchmark is a set of attributes with values determined from either a single

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or a number of reference sites that represent the variability of the vegetation type (Thackway et al. 2006). The reference sites should be located precisely and their benchmark values recorded at known times. A single site may be assessed from more than one perspective, depending on the focus of the condition assessment (Table 29). For example: s a ‘native vegetation integrity’ perspective would interest a biodiversity manager and should be compared to ‘fully natural’ benchmarks s a ‘fodder production’ perspective would interest a grazing property manager and should be compared to ‘best-practice sustainable production’ benchmarks s a ‘carbon sequestration’ perspective would interest a climate-change mitigation manager and should be compared to ‘optimum sustainable carbon capture or storage’ benchmarks. Vegetation that is native, non-native or at different growth stages should each have its own benchmark. For native vegetation, the benchmarks should be based on the best examples representing pre-European conditions (sometimes called ‘fully natural’). For vegetation managed for economic production, benchmarks should be based on reference sites with best-practice, fully ecologically sustainable conditions. Determine whether a benchmark exists for the vegetation being sampled, or whether published descriptions of the attributes of such sites exist. Record the benchmark for the sample site. Vegetation Assets States and Transitions (VAST) may offer an approach for translating, classifying and reporting the condition scores or states of vegetation at a range of scales. It is a classification approach that identifies a minimum of six states relative to the level of ‘modification’ and management of vegetation in the landscape (Thackway and Lesslie 2006). The diagnostic attributes for VAST include floristics, structure and regenerative capacity. For assessing site-based remnant vegetation, particularly for biodiversity condition in native forest in south-eastern Australia, the attributes in Parkes et al. (2003) may be suitable. Although the biodiversity condition of rangelands has received considerable research attention, final recommendations for assessing condition are not yet available (Smyth et al. 2003). Eyre et al. (2006) are using similar attributes to Parkes et al. (2003) and applying them to all vegetation in Queensland for biodiversity condition. Rangeland condition with respect to pastoral production

121

Advanced regeneration

2

Uneven age

Early regeneration

1

3

Growth stage

Code

122 Mixed size and age classes, usually identified by two or more strata dominated by the same species, but can also be sites with different species regenerating in the understorey of an older canopy.

Dominated by dense to sparse, well-developed, immature plants. Large emergents can be present with crown cover <5% of the total crown cover. However, if the cover is >5%, classify as ‘uneven age’. Trees have welldeveloped stems (poles). Crowns have small branches. The height is below maximum height for the stand type. Apical dominance still apparent in vigorous trees.

Dominated by small, juvenile, dense to very sparse regenerating plants, with or without a few older, widely spaced, emergent plants.

Trees dominant

Table 28 Indicators of growth stage

Mixed size and age classes; usually two or more strata dominated by the same species, but includes sites with different species regenerating in the understorey of an older canopy.

Dominated by dense to sparse, well-developed but not mature plants. If large emergent plants are present, then they occupy <5% crown cover of the dominant stratum; if >5%, classify as ‘uneven age’.

Dominated by small, juvenile, dense to very sparse regenerating plants. A few older, widely spaced emergents may be present.

Shrubs dominant

A mixture of mature, perennial and immature annual species present on site.

Vegetative growth abundant; plants approaching full mature size but reproductive material absent or in early stages only; soil surface largely obscured in average sites.

Plants small and juvenile stages predominate; bare soil or old litter common.

Grasses and herbs dominant

A mixture of mature reproductive plants with immature regeneration.

Cover of plants high for the site; some reproduction may be evident.

Thin growth of young plants or widely spaced clumps of young plants.

Cryptogams dominant (mosses and lichens)

Australian Soil and Land Survey Field Handbook

Growth stage

Mature phase

Senescent phase

Code

4

5 Dominated by overmature plants particularly in the dominant stratum; evidence of senescence in many plants, some without obvious links to disturbance. Tree crowns show signs of contracting: dead branches and decreased crown diameter and leaf area. Distorted branches and burls may be common. Dead trees may be present.

Well-spaced mature-sized plants or densely packed plants with crowns touching, with or without emergent senescent plants. Trees at maximum height for the type and conditions. Crown at full lateral development in unlocked stands. No apical dominance.

Trees dominant

Dominated by old plants (thick stems and primary branches, crowns either extremely dense with much dead wood or thin and open if species sheds dead branches), particularly in the dominant stratum. Many senescent plants, some without obvious links to disturbance.

May have well-spaced mature-sized plants, or have very densely packed plants with crowns touching, with or without emergent senescent plants.

Shrubs dominant

In largely annual vegetation, reproduction is complete and plants are dying or mostly dead; in perennial vegetation, plants have lost vigour, are breaking down; large areas of soil are exposed. Litter accumulation may be high.

Most plants of reproductive age; depending on vegetation type, reproduction evident, or would be if environmental conditions were appropriate (e.g. water availability).

Grasses and herbs dominant

Clear evidence of the degeneration of plants or clumps; dead older parts of plants may be conspicuous.

Swards of plants common; plants of mature physiognomy (clump sizes and forms); reproduction common at appropriate times of year or drought/rain cycle; overall health and vigour high.

Cryptogams dominant (mosses and lichens)

Vegetation

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(a) forests (Preston 1997)

1

2

4

5

5

5

5

(b) woodland

1

2

4

5

5

(c) shrubs (Lange and Purdie 1976)

1

1

2

2

4

5

Figure 10 Growth stages. The numbers underneath refer to growth stage categories in Table 28.

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Table 29 Scoring vegetation using benchmarks This example scores three vegetation types based on two different benchmarks. The score in each cell has a potential maximum of 100.

Score relative to preEuropean benchmark

Score relative to sustainable production benchmark (grazing cattle)

Remnant native closed to mid-dense trees (forest)

90

20

Grazed sparse trees (woodland)

55

85

Wheat field

5

25

Type/use

has been assessed for many decades with on-ground surveys (Holm et al. 1987). If a benchmark is available, compare the sample site to the standard for each of the attributes identified for that type of condition (for example biodiversity, commercial production, water resource). Rank the site accordingly. Parkes et al. (2003 and 2004) describe how to deal with site and reference site variability; they also suggest methods for evaluating and scoring sites. McCarthy et al. (2003) provide suggestions for improvements. If no benchmark is available, and the sample is native vegetation, provide a qualitative assessment using the attributes provided in Thackway and Lesslie (2005), where VAST I is the benchmark.

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L A N D SU R FAC E R.C. McDonald, R.F. Isbell and J.G. Speight

This chapter is concerned mainly with surface phenomena affecting land use and soil development that have traditionally been noted at the point of soil observation. Most of the attributes for land surface that are described have implications regarding the use of land; some may also reflect significant processes occurring within the soil (e.g. microrelief). Some attributes (e.g. disturbance of site, erosion) may reflect the influence of present or past land use practice, but it is important that their status be recorded at a known time. It may be difficult to provide a reasonable estimate of some other required attributes (e.g. likely inundation), but the field observer usually has the benefit of some local experience and is better placed to make such an estimate than a subsequent user of the data.

ASPECT Give as compass bearing to nearest 10 degrees. On level lands (less than 1% slope), aspect need not be recorded.

ELEVATION Means of evaluation of elevation L

Levelled from survey datum or estimated from contour plan (1:10 000 or larger scale)

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M

Interpolated from contour map with contour interval of 20 m or less

A

Determined by altimeter

E

Estimate

Elevation value Give in metres above sea level.

DRAINAGE HEIGHT This is the height of the point of soil observation above the flat, depression or stream channel that forms the effective bottom of the toposequence (page 28).

Means of evaluation of drainage height As in the previous section ‘Elevation’.

Drainage height value Give drainage height in metres.

DISTURBANCE OF SITE These are broad categories of disturbance. Users may subdivide where considered necessary. 0

No effective disturbance; natural

1

No effective disturbance other than grazing by hoofed animals

2

Limited clearing (e.g. selective logging)

3

Extensive clearing (e.g. poisoning, ringbarking)

4

Complete clearing; pasture, native or improved, but never cultivated

5

Complete clearing; pasture, native or improved, cultivated at some stage

6

Cultivation; rainfed

7

Cultivation; irrigated, past or present

8

Highly disturbed (e.g. quarrying, road works, mining, landfill, urban)

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MICRORELIEF Microrelief refers to relief up to a few metres about the plane of the land surface. It includes gilgai, hummocky, biotic and other microrelief. Give the type of microrelief within the site: Z

Zero or no microrelief

Gilgai microrelief Gilgai is surface microrelief associated with soils containing shrink–swell clays. It does not include microrelief that apparently results from repeated freezing and thawing, solifluxion or faunal activity. Gilgai consist of mounds and depressions showing varying degrees of order, sometimes separated by a subplanar or slightly undulating surface. In order of increasing dimensions, gilgai types are: C

Crabhole gilgai

irregularly distributed, small depressions and mounds separated by a more or less continuous shelf. Vertical interval usually less than 0.3 m. Horizontal interval usually 3–20 m, surface almost level.

N

Normal gilgai

irregularly distributed, small mounds and subcircular depressions varying in size and spacing. Vertical interval usually less than 0.3 m, horizontal interval usually 3–10 m, surface almost level.

L

Linear gilgai

long, narrow, parallel, elongate mounds and broader elongate depressions more or less at right angles to the contour. Usually in sloping lands. Vertical interval usually less than 0.3 m, horizontal interval usually 5–8 m.

A

Lattice gilgai

discontinuous, elongate mounds and/or elongate depressions more or less at right angles to the contour. Usually in sloping lands, commonly between linear gilgai on lower slopes and plains.

M

Melonhole gilgai

irregularly distributed, large depressions, usually greater than 3 m in diameter or greatest dimension, subcircular or irregular and varying from closely spaced

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in a network of elongate mounds to isolated depressions set in an undulating shelf with occasional small mounds. Some depressions may also contain sinkholes of gilgai usually greater than 0.3 m; horizontal interval usually 5–6 m; surface almost level. G

Contour gilgai

long, elongate depressions and parallel adjacent downslope mounds, which follow the contour. These depression–mound associations are separated from each other by shelves 10–100 m wide. Depressions are up to 0.5 m deep and 30–50 m wide. Mounds are low, usually less than 0.5 m high, and often poorly defined (after Lawrie 1978).

Proportions of gilgai components Give the proportions of gilgai components within the site, thus: A

Equal mounds and depressions; no shelf present

B

More mounds than depressions; no shelf present

C

Fewer mounds than depressions; no shelf present

D

Mound, shelf and depressions; shelf forms prominent part of gilgai

Hummocky microrelief Hummocky microrelief is not thought to be associated with the shrink–swell process involved in gilgai microrelief. D

Debil-debil

small hummocks rising above a planar surface. They vary from rounded, both planar and vertically, to flattopped, relatively steep-sided and elongate. They are usually closely and regularly spaced, ranging from 0.06 m to 0.6 m in both vertical and horizontal dimensions. They are common in northern Australia on soils with impeded internal drainage and in areas of short seasonal ponding. Many observers consider them to be formed by biological activity.

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W

Swamp hummock

steep-sided hummocks rising above a flat surface. Hummocks are frequently occupied by trees or shrubs while the lower surface may be vegetation free or occupied by sedges or reeds. They are subject to prolonged seasonal flooding.

Biotic microrelief This relief is caused by biotic agents (e.g. termite mounds, rabbit warrens, wombat burrows, pig wallows, constructed terraces, stump holes, vegetation mounds). No subdivision of any of the types of biotic microrelief according to the specific agent or component of relief is given here. For example, vegetation mounds are mounds of soil material found at the base of plants such as Dillon bush (Nitraria billardieri) or spinifex (Triodia species). Users may subdivide types of biotic microrelief where considered necessary, such as specifying the particular species of vegetation involved in the case of vegetation mounds. For example, termite mounds would be coded TM.

Agent N

Animal

M

Man

B

Bird

T

Termite

A

Ant

V

Vegetation

O

Other

Component of relief M

Mound

E

Elongate mound

D

Depression

L

Elongate depression

H

Hole

T

Terrace

O

Other

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Other microrelief U

Mound/ depression microrelief

undifferentiated, irregularly distributed or isolated mounds and/or depressions set in a planar surface.

K

Karst microrelief

depressions in limestone country.

I

Sinkhole

closed depression with vertical or funnel-shaped sides.

S

Mass movement microrelief

hummocky microrelief on the surface of landslides, slumps, earth flows, debris avalanches.

R

Terracettes

small terraces on slopes resulting either from soil creep or trampling by hoofed animals.

T

Contour trench

trenches typically 0.2 m deep and 0.6 m wide, with near vertical walls, alternating with flatcrested ridges about 1.3 m wide, which extend along the contour for several metres or tens of metres. Contour trenches are known in areas in south-eastern Australia above 350 m altitude with a high effective rainfall, where they are associated with a grassland or heathland vegetation on undulating rises (compare with McElroy 1952).

P

Spring mound

Mound associated with water flowing from rock or soil without human intervention.

H

Spring hollow

Depression associated with water flowing from rock or soil without human intervention.

O

Other microrelief

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Vertical interval Give vertical distance, in metres, between base of depression or flat and horizontal line joining crests of mounds or hummocks.

Horizontal interval Give horizontal distance, in metres, between crests of mounds or tops of hummocks.

Component of microrelief sampled Give the component of the microrelief in which the described soil profile is located. M

Mound

convex; long axis8 not more than 3 times the shorter axis.

E

Elongate mound

convex; long axis8 more than 3 times the shorter axis.

D

Depression

concave; occurs as closed form.

L

Elongate depression

concave; occurs as open-ended form.

S

Shelf

more or less planar; occurs between mounds and depressions.

K

Hummock

rises above a flat or planar surface. Sides vary from rounded to near vertical and tops from rounded to flat.

F

Flat

surface in which hummocks, mounds, depressions or sinkholes are set.

EROSION This section is concerned with accelerated erosion rather than natural erosion. Natural or geologic erosion is the type and rate of movement of land surface material in its undisturbed natural environment. Accelerated erosion is the 8

Axis in the plane of the land surface.

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more rapid erosion that follows the destruction or loss of protective cover often resulting from people’s influence on the soil, vegetation or landform. It is not always easy to distinguish between accelerated and natural erosion in some landscapes where both are closely interrelated, nor is it always clear whether wind or water is the dominant agent. This is particularly so in the case of scald formation (Warren 1965). The complexity of erosion forms creates difficulties in both defining and quantitatively estimating the extent of erosion within the dimensions of the site. Hence, the observer is advised to record the following simple parameters. Assess the erosion observed at the time of the description, not the likelihood of erosion. For erosion, aggradation and inundation assessment, the extent of the site is 20 m radius.

State of erosion A

Active

one or both of the following conditions apply: evidence of sediment movement; sides and/or floors of erosion form are relatively bare of vegetation.

S

Stabilised

one or both of the following conditions apply: no evidence of sediment movement; sides and/or floors of erosion form are revegetated.

P

Partly stabilised

evidence of some active erosion and some evidence of stabilisation.

Wind erosion W Give presence/absence or extent of accelerated erosion. X

Not apparent

0

No wind erosion

1

Minor or present

some loss of surface.

2

Moderate

most or all or surface removed leaving soft or loose material.

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3

Severe

most or all of surface removed, leaving hard material.

4

Very severe

deeper layers exposed, leaving hard material (e.g. subsoil, weathered country rock or pans).

Scald erosion C This is the removal of surface soil by water and/or wind, often exposing a more clayey subsoil which is devoid of vegetation and relatively impermeable to water. Scalds are most common in arid or semi-arid lands. 0

No scalding

1

Minor scalding <5% of site scalded. Moderate scalding 5–50% of site scalded. Severe scalding >50% of site scalded.

2 3

Water erosion Give type and presence/absence or extent of accelerated erosion. For sheet, rill and gully erosion there is no consensus in Australia on a quantitative or precise definition of what constitutes minor, moderate and severe erosion. This derives partly from the difficulty of measuring actual soil loss at a site. It also derives partly from the wide range of soils, climates and land uses, variations in any or all of which may alter the concept of minor, moderate or severe erosion. The observer wishing to record the severity of erosion may record it as minor, moderate or severe, basing the assessment on local knowledge and guided by indicators that may be present as described below (after Morse et al. 1987). Note the actual depth of soil loss where this can be reliably assessed.

Sheet erosion S This is the relatively uniform removal of soil from an area without the development of conspicuous channels. Indicators of sheet erosion include soil deposits in downslope sediment traps, such as fencelines or farm dams, and pedestalling, root exposure or exposure of subsoils.

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X

Not apparent

0

No sheet erosion

1

Minor

indicators may include shallow soil deposits in downslope sediment traps (fencelines, farm dams). Often very difficult to assess as evidence may be lost with cultivation, pedoturbation or revegetation.

2

Moderate

indicators may include partial exposure of roots, moderate soil deposits in downslope sediment traps (fencelines, farm dams).

3

Severe

indicators may include loss of surface horizons, exposure of subsoil horizons, pedestalling, root exposure, substantial soil deposits in downslope sediment traps (fencelines, farm dams).

Rill erosion R A rill is a small channel up to 0.3 m deep, which can be largely obliterated by tillage operations (Houghton and Charman 1986). 0 1 2 3

No rill erosion Minor Moderate Severe

occasional rills. common rills. numerous rills forming corrugated ground surface.

Gully erosion G A gully (see page 39) is a channel more than 0.3 m deep. 0

No gully erosion

1

Minor

gullies are isolated, linear, discontinuous and restricted to primary or minor drainage lines.

2

Moderate

gullies are linear, continuous and restricted to primary and minor drainage lines.

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Land Surface

3

Severe

gullies are continuous or discontinuous and either tend to branch away from primary drainage lines and on to footslopes, or have multiple branches within primary drainage lines.

Gully depth This gives the maximum depth within the site. 1

<1.5 m

2

1.5–3.0 m

3

>3 m

Tunnel erosion T This is the removal of subsoil by water while the surface soil remains relatively intact (Crouch 1976). X

Not apparent

0

No tunnel erosion

1

Present

Stream bank erosion B This is the removal of soil from a stream bank, typically during periods of high stream flow. X

Not apparent

0

No stream bank erosion

1

Present

Wave erosion V Erosion of beaches, beach ridges and/or dunes. This is the removal of sand or soil from the margins of beaches, beach ridges, dunes, lakes or dams by wave action. X

Not apparent

0

No wave erosion

1

Present

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Mass movement M This includes all relatively large downslope movement of soil, rock or mixture of both (e.g. landslides, slumps, earth flows, debris avalanches and solifluxion). 0

No mass movement

1

Present

AGGRADATION This refers to the presence of material deposited on a pre-existing surface as a result of wind and/or water erosion. X

Not apparent

0

No aggradation

1

Present

INUNDATION Inundation includes flooding from overbank flow, inundation from local runon and overland flow. Although the importance of this information is considerable, in most instances it cannot be assessed at each site. Some evidence may be available from past events (e.g. accumulation of debris in trees or on fences). Otherwise information is usually obtained from local enquiry.

Frequency Give long-term average of inundation. Among alluvial plains, flood plains typically fall in categories 4 and 3. 0

No inundation

1

Less than one occurrence per 100 years

2

One occurrence in between 50 and 100 years

3

One occurrence in between 10 and 50 years

4

One occurrence in between 1 and 10 years

5

More than one occurrence per year

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Land Surface

Duration (annual) Give likely duration of an inundation event. 1

Less than 1 day

2

Between 1 and 20 days

3

Between 20 and 120 days

4

More than 120 days

Depth (annual) Give likely maximum depth of water in an inundation event. 1

<50 mm

2

50–100 mm

3

100–300 mm

4

300–1000 mm

5

>1000 mm

Runon velocity As a guide, the surface velocity in a river is typically 1–2 m/s. L

Low velocity <300 mm/s

H

High velocity >300 mm/s

COARSE FRAGMENTS Coarse fragments are particles coarser than 2 mm. They include unattached rock fragments and other fragments such as charcoal and shells. Coarse fragments are distinguished from segregations of pedogenic origin (see page 195) in that they are not, or not considered to be, of pedogenic origin. Both coarse fragments and segregations of pedogenic origin can occur on the surface. Where segregations of pedogenic origin occur on the surface, they should be described as on page 195.

Abundance of coarse fragments The percentage is estimated by eye using the charts in Figure 11 for comparison.

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0 1 2 3

4 5 6

No coarse fragments 0 Very slightly or very few, for example very slightly fine gravelly; very few small pebbles <2% Slightly or few, for example slightly stony; few stones 2–10% No qualifier or common, for example medium gravelly; stony, common medium pebbles; common stones 10–20% Moderately or many Very or abundant Extremely or very abundant

20–50% 50–90% >90%

Size of coarse fragments The scale adopted uses class boundaries at (2 × 10n/2) mm, where n is an integer. This system is an extension of that used for particles smaller than 2 mm both in the scheme of the British Standards Institution and the Massachusetts Institute of Technology (see Figure 15, page 162) and the original Atterberg (1905) scheme on which the International Scheme was based. It is thus compatible with both the International Scheme referred to in the field texture section (page 161) and the grain size criteria for substrate materials (page 206). The terms used to describe size apply to fragments of any shape. The average maximum dimension of fragments is used to determine the class interval. 1 2 3 4 5 6 7

9

Fine gravelly9 or small pebbles Medium gravelly or medium pebbles Coarse gravelly or large pebbles Cobbly or cobbles

2–6 mm 6–20 mm 20–60 mm 60–200 mm

Stony or stones Bouldery or boulders Large boulders

200–600 mm 600–2000 mm >2000 mm

Note that in preparing soils for laboratory analysis, the greater than 2 mm size fraction is commonly recorded as ‘gravel’.

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Figure 11 Chart for estimating abundance of coarse fragments (page 139), mottles (pages 159–60), and segregations of pedogenic origin (page 195). Each quarter of any one square has the same area of black.

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Shape of coarse fragments Give shape using Figure 12 as a visual guide. A S U

Angular Subangular

UP

Subrounded Rounded Angular tabular Subangular tabular Subrounded tabular Rounded tabular Angular platy Subangular platy Subrounded platy

RP

Rounded platy

R AT ST UT RT AP SP

Lithology of coarse fragments M

Same as substrate material (page 209)

R

Same as rock outcrop (pages 143–4)

Where the lithology of coarse fragments is different from that of either the substrate material, the rock outcrop or both, describe it as for lithology of substrate material (see Table 35, page 214). Some coarse fragments are commonly encountered that are not listed in any category above. These include: IS SS CC PU OW OT

Ironstone (where not considered of pedogenic origin) Shells Charcoal Pumice Opalised wood Other

Strength of coarse fragments Same as for ‘Strength of material’ (see page 209).

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Land Surface

Roundness

Tabular

Platy

R

R

RT

RP

R

R

RT

RP

Rounded

Subrounded U

U

UT

UP

Subangular S

S

ST

SP Angular

A

A

AT

AP

Sphericity Figure 12 Coarse fragment shape.

ROCK OUTCROP This refers to any exposed area of rock that is inferred to be continuous with underlying bedrock.

Abundance of rock outcrop 0 1 2

No rock outcrop Very slightly rocky Slightly rocky

no bedrock exposed. <2% bedrock exposed. 2–10% bedrock exposed. 143

Australian Soil and Land Survey Field Handbook

3 4 5

Rocky Very rocky Rockland

10–20% bedrock exposed. 20–50% bedrock exposed. >50% bedrock exposed.

Lithological type of rock outcrop Where the lithology of the rock outcrop is different from that of the substrate material, record it as for lithology of substrate material (see page 214, Table 35).

DEPTH TO FREE WATER Give depth to free water at the site of soil observation, in metres, either above or below the soil surface, excluding litter and living vegetation. Prefix the depth above or below the soil surface as follows: +

Above soil surface

–

Below soil surface

If there is no free water, record: 0

No free water

RUNOFF Runoff is the relative rate at which water runs off the soil surface. It is largely determined by slope, surface cover and soil infiltration rate. 0

No runoff

1

Very slow

free water on surface for long periods, or water enters soil immediately. Soils usually either level to nearly level or loose and porous.

2

Slow

free water on surface for significant periods, or water enters soil relatively rapidly. Soils usually either nearly level to gently sloping or relatively porous.

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Land Surface

3

Moderately rapid

free water on surface for short periods only; moderate proportion of water enters soil.

4

Rapid

large proportion of water runs off; small proportion enters soil. Water runs off nearly as fast as it is added. Soils usually have moderate to steep slopes and low infiltration rates.

5

Very rapid

very large proportion of water runs off; very small proportion enters soil. Water runs off as fast as it is added. Soils usually have steep to very steep slopes and low infiltration rates.

145

SOI L PROF I L E R.C. McDonald and R.F. Isbell

A soil profile is a vertical section of a soil from the soil surface through all its horizons to parent material, other consolidated substrate material or selected depth in unconsolidated material. A soil profile can be seen as an individual (Macvicar 1969, page 143; Northcote 1979, page 22) that is described by giving a single value to each property. This is distinct from the pedon (Soil Survey Staff 1975), a threedimensional soil body that can only be described by a range of values for each property. Considering the variability inherent in soils, ideally a soil description would give a range of values for each property recorded in each of the three dimensions in each horizon. In practice this is not possible as the pedologist can describe factually only the very small parts of the soil body actually seen. Most soil descriptions are given with a single value for each property described and thus refer to soil profiles.

TYPE OF SOIL OBSERVATION The soil profile may be described from the following (listed in order of preference): P

C

Soil pit Existing vertical exposure Relatively undisturbed soil core

A

Auger boring

E

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Australian Soil and Land Survey Field Handbook

To characterise a soil profile fully, it should be examined to the depth of the parent material or other consolidated material. However, because soil depth varies between very wide limits and because soils are examined for a wide variety of purposes, the depth of examination in practice frequently may not exceed 1.5–2 m.

HORIZONS A soil horizon is a layer of soil, approximately parallel to the land surface, with morphological properties different from layers below and/or above it. Tongues of material from one horizon may penetrate into adjacent horizons. Give horizon notation as described below. As horizon notation is deduced from the profile description data (Northcote 1979) and in some instances laboratory data, record it after the profile is described. Horizons may be difficult to name, but should be named in the field. Opinions formed at the time of description are useful for later reference. With regard to horizon notation, the long-established usage in horizon designation is adopted. Emphasis is on factual objective notation rather than assumed genesis, as genetic implications are often uncertain and difficult to establish. Thus the notation ‘E’ indicating eluvial horizon (International Society of Soil Science 1967) has not been used, even though this has been adopted by several organisations in other countries (e.g. Hodgson 1974; Soil Survey Staff 1990). O

horizons

These are horizons dominated by organic materials in varying stages of decomposition that have accumulated on the mineral soil surface. They are usually divided into O1 and O2 horizons. O1 horizon

consists of undecomposed organic debris, usually dominated by leaves and twigs. The original form of the debris can be recognised with the naked eye.

O2 horizon

consists of organic debris in various stages of decomposition. The original form of most of the debris cannot be recognised with the naked eye.

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Soil Profile

P

horizons

These are horizons dominated by organic materials in various stages of decomposition that have accumulated either under water or in conditions of excessive wetness. They have long been known as peat. The organic material consists of the remains of plants that have been growing in place. They may be divided into P1 and P2 horizons as in O1 and O2 above. When such horizons are buried, they may be designated in a manner similar to designations for buried mineral soils (page 156), for example 2P1, 3P2, etc. P1 horizon

consists primarily of undecomposed or weakly decomposed organic material (fibric peat). Plant remains are distinct and readily identifiable.

P2 horizon

consists primarily of moderately to completely decomposed organic material (hemic to sapric peat). Plant remains vary from being difficult to identify to completely amorphous.

A

horizons

These are horizons either consisting of one or more surface mineral horizons with some organic accumulation and usually darker in colour than the underlying horizons, or consisting of surface and subsurface horizons that are lighter in colour but have a lower content of silicate clay and/or sesquioxides than the underlying horizons. A1 horizon

mineral horizon at or near the soil surface with some accumulation of humified organic matter, usually darker in colour than underlying horizons and with maximum biologic activity for any given soil profile. It may be divided into subhorizons and of these the A11 horizon is usually the more organic, or darker coloured uppermost portion. The A12 differs in either hue, value or chroma from the A11, usually being lighter in colour. It is not pale enough to qualify as an A2 horizon. The A1 may be further divided into subhorizons if necessary (e.g. A13, A14).

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Australian Soil and Land Survey Field Handbook

A2 horizon

mineral horizon having, either alone or in combination, less organic matter, sesquioxides, or silicate clay than immediately adjacent horizons. It is usually differentiated from the A1 horizon by its paler colour, that is, by having colour value at least one unit higher and usually less organic matter. It is usually differentiated from the B horizon by having colour value at least one unit higher and chroma at least two units lower, by coarser texture or by a combination of these attributes.

A3 horizon

transitional horizon between A and B, which is dominated by properties characteristic of an overlying A1 or A2.

B

horizons

These are horizons consisting of one or more mineral soil layers characterised by one or more of the following: a concentration of silicate clay, iron, aluminium, organic material or several of these; a structure and/or consistence unlike that of the A horizons above or of any horizons immediately below; stronger colours, usually expressed as higher chroma and/or redder hue, than those of the A horizons above or those of the horizons below. B1 horizon

transitional horizon between A and B, which is dominated by properties characteristic of an underlying B2.

B2 horizon

horizon in which the dominant feature is one or more of the following: s ANILLUVIAL RESIDUALOROTHERCONCENTRATIONOFSILICATE clay, or iron, aluminium or humus, either alone or in combination s M AXIMUMDEVELOPMENTOFPEDOLOGICORGANISATION10 as evidenced by a different structure and/or consistence, and/or stronger colours than the A horizons above or any horizon immediately below. It may be divided into subhorizons (e.g. B21, B22, B23).









10

Pedologic organisation is a broad term used to include all changes in soil material resulting from the effect of physical, chemical and biologic processes, that is, soil formation. Results of these processes include horizontation, colour differences, presence of pedality, and texture and/or consistence changes.

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Soil Profile

B3 horizon

C

transitional horizon between B and C or other subsolum material in which properties characteristic of an overlying B2 dominate, but intergrade to those of the underlying material.

horizons

These are layers below the solum (AB profile) of consolidated or unconsolidated material, usually partially weathered, little affected by pedogenic processes, and either like or unlike the material from which the solum presumably formed. The C horizon lacks properties characteristic of O, P, A, B or D horizons. It is recognised by its lack of pedological development and/or the presence of geologic organisation frequently expressed as sedimentary laminae or as ghost rock structure as in saprolite. C horizons include consolidated rock and sediments that, when moist, can be dug with hand tools. Rock strength is generally weak or weaker. Because of their nature, C horizons may be described as detailed in this chapter or as substrate (see page 205). D

horizons

These are considered here to be any soil material below the solum that is unlike the solum in its general character, is not C horizon, and cannot be given reliable horizon designation as described in ‘Lithologic discontinuities’ or ‘Buried soils’ (see page 156). Thus, a D horizon may be recognised by the contrast in pedologic organisation between it and the overlying horizons. R

horizons

These horizons consist of continuous masses (not boulders) of moderately strong to very strong rock (excluding pans, page 192) such as bedrock. R horizons may have cracks but these are few enough and/or fine enough that few roots penetrate and there is no significant displacement of rock. It is usually too strong to dig with hand tools, even when moist.

Transitional horizons Two main kinds are distinguished: s transitional horizons that have subordinate properties of both horizons but are not dominated by properties characteristic of either horizon. For example, AB, AC, BC horizons.

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Australian Soil and Land Survey Field Handbook

s transitional horizons in which distinct parts have recognisable properties of two kinds of horizons indicated by capital letters (Soil Survey Staff 1990). The two capital letters are separated by a virgule (/) as A/B, A/C, B/C. Most of the individual parts of at least one of the components are surrounded by the other. The first symbol is that of the horizon that makes up the greater volume.

Bleached horizons Some horizons are white, near white or much paler than adjacent horizons. Bleached horizons most commonly occur as A2 horizons but are not restricted to them. Bleached horizons are defined in terms of Munsell notations for dry soil: s for all hues, value 7 or greater with chroma 4 or less s where adjacent horizons have hues 5YR or redder, value 6 or greater with chroma 4 or less. Two kinds of bleached horizons are recognised: Conspicuously bleached: 80% or more of the horizon is bleached. Sporadically bleached: bleach occurs: s irregularly through the horizon s as blotches, often less than 6 mm thick, at the interface of horizons, most commonly A and B horizons s as nests of bleached grains of soil material at the interface of horizons, most commonly A and B horizons, when no other evidence of a bleached horizon may occur.

Cracking clays The A and B horizons in cracking clays are defined and recognised on the basis of structure rather than colour (McDonald 1977). The A horizon in cracking clays may be structured or massive. The structural A horizon is the granular, subangular blocky, angular blocky or polyhedral surface horizon where ped faces are not accommodated and have irregular coarse voids between them. This is exemplified in soils with a self-

152

Soil Profile

mulching surface. The A horizon structure is unstable only in the sense that relatively rapid wetting and drying continually creates new peds and voids. The B horizon is the coarse angular blocky and/or lenticular horizon where ped faces are all accommodated and usually have only narrow planar voids between them. The B horizon structure is stable because of relatively slow wetting and drying. The B horizon will usually occur within 200 mm of the surface, but the structural change must be confirmed using a spade or exposure to examine the soil. The boundary may often be gradual or diffuse, but can be clear or abrupt.

Horizon suffixes b11

used for buried soil horizons. Used in mineral soils only. The suffix is written last (e.g. 2B2b).

c

used for horizons with accumulation of concretions or nodules of iron and/or aluminium and/or manganese, as in B2c.

d

used for densipans. Very fine, sandy, earthy pan (see page 194).

e

used for conspicuously bleached horizons (e.g. A2e).

f

used when faunal accumulation, such as worm casts, dominates certain A1 horizons (e.g. A1f in some soils under rainforest).

g

indicates strong gleying, as in B2g. Gleying is indicative of permanent or periodic intense reduction due to wetness; it is characterised by greyish, bluish or greenish colours, generally of low chroma. Mottling may be prominent; mottles may have reddish hues and higher chromas if oxidising conditions occur periodically. Roots may have rusty or yellowish outlines; hence horizons such as A1g can occur.

h

used where horizons contain accumulation of amorphous, organic matter–aluminium complexes in which iron contents are very low. The dominantly organic matter–aluminium complexes occur as discrete pellets between clean sand grains or completely fill the voids; occasionally they may coat sand grains. Such horizons may be soft or

11

This suffix should only be used according to the definition of buried soils on page 156.

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Australian Soil and Land Survey Field Handbook

cemented and form the characteristic B horizon of poorly drained soils known as podzols or Podosols. j

used for sporadically bleached horizons (e.g. A2j).

k12

used for horizons with accumulation of carbonates, commonly calcium carbonate, as in B2k.

m

used for horizons with strong cementation or induration. It is confined to irreversibly cemented horizons that are essentially continuous (>90%) though they may be fractured.

p

used for horizons where ploughing, tillage practices or other disturbance by humans has occurred (e.g. deep ripping). This suffix is used only with A, as in Ap2. Where the plough layer clearly includes what was once B horizon and it is no longer possible to infer with any reliability what the texture and depth of the A horizon was, the plough layer is designated Ap. An Ap horizon may be subdivided into subhorizons (e.g. Ap1, Ap2). Note: An Ap2 horizon is not the same as an A2 horizon but a subdivision equivalent to A12.

q

used for horizons with accumulation of secondary silica. If silica cementation is continuous or nearly continuous, ‘qm’ is used.

r

used for horizons with layers of weathered rock (including saprolite) that, although consolidated, can be dug with hand tools.

s

used for horizons with an accumulation of sesquioxide–organic matter complexes in which iron is dominant relative to aluminium. These complexes coat sand grains, occur as discrete pellets, or, with moderate amounts of iron, may fill voids forming cemented patches. The content of organic matter is variable and its distribution is often irregular. The suffix ‘s’ is often used in combination with ‘h’ (as in

12

These suffixes are usually recorded only if there is a common or larger abundance of these segregations (see page 195). Horizons with few (2–10%) or very few (<2%) segregations are not usually given these horizon notations. These suffixes indicate relative accumulations compared with other horizons. Thus, in a soil with no carbonate except for one horizon with few segregations, this horizon could be designated with a suffix ‘k’ (e.g. B22tk). However, in a soil with few segregations of carbonate throughout, no horizon would be given the suffix ‘k’ unless it had common or more segregations (i.e. a relatively larger amount than adjacent horizons).

154

Soil Profile

Bhs) where both organic and iron components are significant; s or Bhs horizons may be soft or hard and form the characteristic B horizon of free-draining podzols or Podosols. t

used for horizons with accumulation of silicate clay (from German ton, clay). Different mechanisms (e.g. illuviation, formation in situ) may be responsible for the clay accumulation, but these may be difficult to confirm. This suffix is used only with the B, for example B2t, to indicate the nature of the B.

w

used where development of colour and/or structure, or both, in the B horizon is observed, with little or no accumulation of sesquioxide– organic matter complexes.

x

used for fragipans or earthy pans. A horizon with high bulk density relative to the horizon above, seemingly cemented when dry, but showing a moderate to weak cementation when moist (see page 193).

y 12

used for horizons with accumulation of calcium sulfate (gypsum), as in B21, B22.

z

used for horizons with accumulation of salts more soluble than calcium sulfate and calcium carbonate.

?

query. Used where doubt is associated with the nomenclature of the horizon, with the query following the horizon notation (e.g. ‘D?’).

Subdivision of horizons All horizon subdivisions are numbered consecutively from the top of each horizon downward, as in A11, A12, A2, B21, B22, B23. The numeric suffix always precedes the alphabetic suffix except with the alphabetic suffix ‘p’ where the number always follows the letter. The above horizon nomenclature will cover most soils, but there will be instances where there are buried soils (pedologic discontinuities) (see Figure 14) and also where a profile has formed on what are obviously different parent materials (lithologic discontinuities) (Figure 13). Where there are buried soils and it is not possible to identify reliably the horizon as A or B, then these are D horizons (e.g. Profile E, Figure 13).

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Australian Soil and Land Survey Field Handbook

Lithologic discontinuities Where obvious contrasts in lithology exist between different horizons in the soil profile, or between the soil profile and the underlying lithology, the different lithologic layers are given a numeric prefix (Figure 13). Each layer may consist of one or more horizons. The different layers are numbered from the top downward. The upper layer is not numbered 1, this being understood. Numbering starts with the second layer, which is designated 2. Even though a layer below material 3, for example, is similar to material 2, it is designated 4 in the sequence (see Profiles C and D in Figure 13). Discrimination of lithological discontinuities from soil horizon boundaries will depend in each case upon the degree of pedological organisation and the contrast between lithological units (e.g. see Profiles C and D in Figure 13). Where lithologic discontinuities are suspected in the profile but there is no clear evidence, either the numeric prefix should not be used or a query should be added to indicate doubt. It is better used only where there is clear evidence. Whether the numeric prefix is used or not, the horizon naming, with appropriate suffixes, remains the same, as illustrated in Figure 13 examples.

Buried soils Where there are buried soils, and it is possible to designate reliably the horizon nomenclature in the buried profiles, the buried horizons are given the suffix ‘b’ which is written last. Number the different soils from the top downward. The upper soil, or modern soil, is not numbered 1, this being understood. Two examples are given in Figure 14.

DEPTH OF HORIZONS The upper and lower depths, in metres, of each horizon are measured from the soil surface, excluding O horizons. O horizon depths are measured above the mineral soil surface (e.g. O1 0.12–0.10 m; O2 0.1–0.0 m). A scaled horizon diagram may be useful where horizons are irregular.

DEPTH TO R HORIZON OR STRONGLY CEMENTED PAN Give depth to R horizon or strongly cemented pan (see page 192) in metres.

156

Soil Profile

Figure 13 Lithologic discontinuities and soil horizon nomenclature. In Profile C, the degree of development of the B22 horizon overrides any lithologic discontinuity between the B22 and 2B22 horizon; hence, no soil horizon boundary is shown between them. In Profile D, lithologic characteristics allow recognition of separate sedimentary layers in the upper solum. The horizon boundary between the A11 and 2A12 is also recognised by the pedological differences within the A1 horizon. However, the gross characteristics of the A2 horizon (e.g. a conspicuous bleach) have developed in two different lithologies in layers 2A2 and 3A2. In Profile E, layer 3D is equivalent to layer 5D in Profiles C and D.

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Australian Soil and Land Survey Field Handbook

Profile Profile A B Present land surface A1 A1 A3

A3

B21

B21

B22

B22

Sedimentary layer 1

Surface of buried soil

2A1b 2A2b

2Db

2B2b

2Cb

Su

e fac

of

Sedimentary layer 2

il so d rie bu

r

3Db

3A1b

Sedimentary layer 3

3Bb 3Cb Figure 14 Buried soils and soil horizon nomenclature. In Profile A, the buried soils have reliably identified horizons; in Profile B, they do not. Buried soils will always be overlain by a sedimentary layer that is different from the material in which they occur. Therefore, lithologic discontinuities in the profile must be designated.

158

Soil Profile

The purpose of recording this depth is to include in the soil description those materials that may be relatively easily moved by earth-moving equipment or may be relatively easily penetrated by roots. Strong or very strong rock or pan that may require ripping or blasting to move, and/or has little or no root penetration, is excluded.

COLOUR Record colours by comparing soils with colour charts using the Munsell Color system, for example the Munsell Soil Color Charts or the Revised Standard Soil Color Charts (Oyama and Takehara 1970). Hue, value and chroma of the matrix colour are recorded, for example 10YR4/2. Soil colours rarely match the chart colour chips perfectly. They should be matched to the chip closest in colour, or the nearest whole number in chroma where chips are not provided (e.g. chromas 5 and 7). The soil colour is measured on the surface of a freshly broken aggregate of moist soil. Moisten the soil if it is dry. Record the colour when the visible moisture film disappears from the surface of the moistened broken aggregate. The aggregate should be held as close as possible to the colour chips. Take care not to smear the broken surface, as this can give an incorrect recording of the colour of the soil matrix. Dry colours may also be recorded.

Moisture status for colour description M

Moist

D

Dry

MOTTLES AND OTHER COLOUR PATTERNS Mottles are spots, blotches or streaks of subdominant colours different from the matrix colour and also different from the colour of the ped surface. Segregations of pedogenic origin are not considered to be mottles and are recorded elsewhere (page 195). Colour patterns due to biological or mechanical mixing and inclusions of weathered substrate material are described separately.

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Australian Soil and Land Survey Field Handbook

Type M

Mottles

X

Colour patterns due to biological mixing of soil material from other horizons (e.g. worm casts).

Y

Colour patterns due to mechanical mixing of soil material from other horizons (e.g. inclusions of B horizon material in Ap horizons).

Z

Colour patterns due to inclusions of weathered substrate material.

Abundance The percentage is estimated by eye using the chart in Figure 11 for comparison (see page 141). 0 1 2 3 4

No mottles or other colour patterns Very few Few Common Many

0 <2% 2–10% 10–20% 20–50%

Size Measure size along the greatest dimension, except in streaks or linear forms where width is measured. 1 2 3 4

Fine Medium Coarse Very coarse

<5 mm 5–15 mm 15–30 mm >30 mm

Contrast F D P

Faint Distinct Prominent

indistinct; evident only on close examination. readily evident although not striking. striking and conspicuous.

160

Soil Profile

Colour This should be described in terms of Munsell or Revised Standard Soil colours, but the following abbreviated forms can be used: R O B Y G D L P

Red Orange Brown Yellow Grey Dark Gley Pale

values 3 or less and chromas 2 or less for all hues. gley charts only. values 7 or more and chromas 2 or less for all hues.

Distinctness of boundaries S C D

Sharp Clear Diffuse

knife-edge boundary between colours. colour transition over less than 2 mm. colour transition over 2 mm or more.

FIELD TEXTURE Soil texture is determined by the size distribution of mineral particles finer than 2 mm; that is, only material that will pass a 2 mm sieve should be used in determination of field texture. Organic soils are discussed on pages 169–70. In Australia, field texture classes or field texture grades (Northcote 1979) are based on field determination of texture and not on laboratory determinations of particle size, as is done in USA for example (Soil Survey Staff 1975). There is only an approximate relationship between field texture and particle size distribution (see Marshall 1947), as factors other than clay, silt and sand content influence field texture. Figure 15 gives a comparison between International particle size fractions, used in Australia, and those of other major classifications. Figure 16 is an example of a triangular texture diagram based on International fractions.

161

CLAY

0.002

0.002

SILT

SILT

0.002

162 10

9

8

7

SILT FINE

6

0.02

5

4

3

0.1

0.074

0.05

FINE

2

0.25

0.212

Figure 15 Size fractions in several major classification systems.

0.075

0.6

1

0.42

2.0

2.0

0

2.36

-1

2.0

6.0

MEDIUM GRAVEL

-2

4.8

6.7

-3

FINE

20

20

COARSE GRAVEL

19

-4

19

-5

63

-6

2000

2000

BOULDERS

600

-7

-8

300

COBBLES

250

-9

-10

BOULDERS

600

2000

2000

COBBLES STONES BOULDERS

76

76

STONES

200

STONES

COBBLES

60

GRAVEL COARSE

GRAVEL

GRAVEL

FINE GRAVEL

COARSE

2.0

V-CSE

1.0

SAND MEDIUM

0.5

CSE

COARSE

COARSE

SAND FINE MED

0.25

SAND

0.2

SAND

EQUIVALENT AUSTRALIAN STANDARD SIEVE APERTURES

11

PHI SCALE

<0.0002

CLAY OR SILT

UNIFIED (CASAGRANDE)

<0.0002

CLAY

FINE

COARSE V-FINE

0.02

0.02

FINE

Particle diameters given in millimetres under each scale

US DEPARTMENT OF AGRICULTURE

<0.0002

CLAY

INTERNATIONAL

0.0002

FINE CLAY

RECOMMENDED SCALE

Australian Soil and Land Survey Field Handbook

Soil Profile

100% CLAY

90

10

80

20

70

30

en

tC

40

60 CLAY LOAM

30

SILTY CLAY LOAM

70

20

SANDY LOAM

100% SAND

50

ilt

40

SANDY CLAY LOAM

SAND

SILTY CLAY

50

Pe rc

SANDY CLAY

S nt rce Pe

lay

CLAY 60

80 LOAM

SILTY LOAM

10

90 LOAMY SAND 90

80

70

60 50 40 Percent Sand

30

20

10

100% SILT

Figure 16 Triangular texture diagram based on International fractions (Marshall 1947).

Mineral soils The following description of determination of field texture is adapted from Northcote (1979). Field texture is a measure of the behaviour of a small handful of soil when moistened and kneaded into a ball and then pressed out between thumb and forefinger. Take a sample of soil sufficient to fit comfortably into the palm of the hand. Moisten the soil with water, a little at a time, and knead until the ball of soil, so formed, just fails to stick to the fingers. Add more soil or water to attain this condition, known as the sticky point, which approximates field capacity for that soil. Continue kneading and moistening until there is no apparent change in

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the soil ball, usually a working time of 1–2 minutes. The soil ball, or bolus, is now ready for shearing manipulation, but the behaviour of the soil during bolus formation is also indicative of its field texture. The behaviour of the bolus and of the ribbon produced by shearing (pressing out) between thumb and forefinger characterises the field texture. Do not assess field texture grade solely on the length of ribbon. The recommended field texture grades as characterised by the behaviour of the moist bolus are set out below. The approximate percentage content of clay (particles <0.002 mm in diameter) and silt (particles 0.02–0.002 mm in diameter) are given as a guide. These percentages must not be used to determine a field texture; that is, do not use them to convert a laboratory particle size value to a field texture grade. Similarly, do not adjust a field texture grade when laboratory particle size data become available.

Field texture grade

Behaviour of moist bolus

Approximate clay content (%)

S

Sand

coherence nil to very slight, cannot be moulded; sand grains of medium size; single sand grains adhere to fingers.

commonly <5%

LS

Loamy sand

slight coherence; sand grains of medium size; can be sheared between thumb and forefinger to give minimal ribbon of about 5 mm.

about 5%

CS

Clayey sand

slight coherence; sand grains of medium size; sticky when wet; many sand grains stick to fingers; will form minimal ribbon of 5–15 mm; discolours fingers with clay stain.

5–10%

SL

Sandy loam

bolus coherent but very sandy to touch; will 10–20% form ribbon of 15–25 mm; dominant sand grains are of medium size and are readily visible.

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Soil Profile

L

Loam

bolus coherent and rather spongy; smooth about 25% feel when manipulated but with no obvious sandiness or ‘silkiness’; may be somewhat greasy to the touch if much organic matter present; will form ribbon of about 25 mm.

ZL

Silty loam

coherent bolus; very smooth to often silky when manipulated; will form ribbon of about 25 mm.

about 25% and with silt 25% or more

SCL

Sandy clay loam

strongly coherent bolus, sandy to touch; medium-size sand grains visible in finer matrix; will form ribbon of 25–40 mm.

20–30%

CL

Clay loam

coherent plastic bolus, smooth to 30–35% manipulate; will form ribbon of 40–50 mm.

CLS

Clay loam, sandy

coherent plastic bolus; medium-size sand grains visible in finer matrix; will form ribbon of 40–50 mm.

30–35%

ZCL

Silty clay loam

coherent smooth bolus, plastic and often silky to the touch; will form ribbon of 40–50 mm.

30–35% and with silt 25% or more

LC

Light clay

plastic bolus; smooth to touch; slight resistance to shearing between thumb and forefinger; will form ribbon of 50–75 mm.

35–40%

LMC

Light plastic bolus; smooth to touch; slight to 40–45% medium moderate resistance to ribboning shear; will clay form ribbon of about 75 mm.

MC

Medium smooth plastic bolus; handles like plasticine 45–55% clay and can be moulded into rods without fracture; has moderate resistance to ribboning shear; will form ribbon of 75 mm or more.

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MHC

Medium smooth plastic bolus; handles like heavy plasticine; can be moulded into rods clay without fracture; has moderate to firm resistance to ribboning shear; will form ribbon of 75 mm or more.

HC

Heavy clay

50% or more

smooth plastic bolus; handles like stiff 50% or more plasticine; can be moulded into rods without fracture; has firm resistance to ribboning shear; will form ribbon of 75 mm or more.

All the above field texture grades in which sand is recorded (e.g. LS, SL) are defined as having medium-sized sand. Coarse or fine sand grades can be given, as below: K

Coarse sandy

coarse sand is obviously coarse to touch. Sand grains are very readily seen with the naked eye.

F

Fine sandy

fine sand can be felt and often heard when manipulated. Sand grains are clearly evident under a ×10 hand lens.

Record K or F immediately preceding S in the texture codes (e.g. LKS, KSL, CLFS). Each of the clay field texture grades may also be modified according to the sand or silt fractions, where K is coarse sandy, S is medium sandy, F is fine sandy and Z is silty. These modifiers immediately precede the clay texture codes (e.g. KSLC for coarse sandy light clay; SLC for sandy light clay; ZLC for silty light clay).

Field texture qualification The non-clay field texture grades (clay loams and coarser) may be qualified according to whether they are at, or near, the light (lower clay content) or heavy (higher clay content) end of the range for that particular field texture grade. Note that codes on pages 165–6 provide for light and heavy qualifiers in the clays and hence – and + are not required.

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– +

Light Heavy

It is strongly recommended that this option be used only where considered essential. If too freely used, it can lead to excessive, unnecessary detail of doubtful usefulness. If the soils are appreciably organic, they are qualified thus: A

Sapric

organic and non-fibrous; dark organic stain discolours fingers; greasy feel in clayey textures and coherence in sandy textures. Fibres (excluding living roots) or plant tissue remains are not visible to naked eye and little or none visible with ×10 hand lens.

I

Fibric

organic and fibrous; dark organic stain discolours fingers; greasy feel in clayey textures and coherence in sandy textures. Fibres (excluding living roots) or plant tissue remain visible to naked eye or easily visible with ×10 hand lens.

These codes are given after the field texture. For example, light sandy clay loam is coded SCL–, heavy sandy clay loam is coded SCL+, and fibric sandy loam is coded SLI.

Soil properties affecting determination of field texture grade Several soil properties affect field texture. These include: s Clay (particles less than 0.002 mm in diameter) confers cohesion, stickiness and plasticity to the bolus and increases its resistance to deformation. s The type of clay mineral influences the tractability of the bolus. Montmorillonitic clays tend to make the bolus resist deformation and therefore it can be stiff to ribbon. Thus, a long ribbon may suggest a finer (more clayey) field texture than the percentage clay content would indicate. By contrast, kaolinitic clays make the field texture appear less

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s

s

s

s

s

s

clayey than the percentage clay content would indicate, as they tend to produce a short thin ribbon from the bolus. Silt (particles 0.002–0.02 mm in diameter) often confers a silky smoothness on field textures, as it fills in the particle size range between sand (particles >0.02 mm in diameter) and clay. Organic matter confers cohesion to sandy field textures and a greasiness to clayey field textures; it tends to produce a short thick ribbon from the bolus. Some soils containing about 40–50% clay-sized particles and sufficient organic matter (>20%) will behave as clay loams and light clays instead of medium or heavy clays. Large amounts of organic matter in dry soils may resist wetting and make bolus preparation difficult. When present in significant amounts, oxides – chiefly those of iron and aluminium – may require extra water for the soil to form the bolus. This may shear readily to produce a short ribbon, indicating a less clayey field texture than the clay content suggests. Such soil materials are subplastic. Calcium and magnesium carbonates in the fine earth fraction (particles <2 mm in diameter) will usually impart a porridge-like consistency to the bolus. They tend to increase the apparent clay content of sandy and loamy field textures such that amounts of 10–30% calcium carbonate cause the field texture to increase about one grade above that obtained when the carbonates are removed from the fine earth fraction. Carbonates may also make clay field textures appear less clayey by shortening the ribbon produced from the bolus. Cation composition. In general, calcium-dominant clays accept water readily and are easy to knead and smooth to field texture. Sodiumdominant and magnesium-dominant clays, however, are often difficult to wet and knead, producing a slimy, tough bolus, resistant to shearing and often appearing to have a more clayey field texture than would be indicated by the actual clay content. Strong, fine-structural aggregation will tend to cause an underestimation of clay content, due to the incomplete breakdown of the structural units during bolus preparation. Longer and more vigorous kneading is necessary to produce a homogeneous bolus.

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Soil Profile

The above properties occur in soils to differing degrees and specific allowance cannot be made for them. Field texture must remain a subjective but reproducible measure of the behaviour of a handful of soil moistened and kneaded into an adequately prepared bolus and subjected to shearing manipulation between thumb and forefinger. However, this method provides a very useful assessment of the physical behaviour of soil in the field.

Organic soils Strictly speaking, organic soils do not have textural names, as soil texture is determined by the size of mineral particles finer than 2 mm (page 161). In a sense, organic soils do have a texture related to the plant materials from which they formed and the degree of decomposition, exposure and drying. The following names may be used to characterise materials that on field examination are considered to be clearly dominated by organic matter. Peats may be assessed by examining the degree of decomposition and distinctness of plant remains. The following is adapted from Soil Survey Staff (1975) and Avery (1980): IP

Fibric peat

(fibrous peat) undecomposed or weakly decomposed organic material. Plant remains are distinct and readily identifiable.

HP

Hemic peat

(semi-fibrous peat) moderately to welldecomposed organic material. Plant remains vary from most being difficult to identify to most being unidentifiable. It is intermediate in degree of decomposition between the less decomposed fibric peat and the more decomposed sapric peat.

AP

Sapric peat

(humified peat) strongly to completely decomposed organic material. Plant remains vary from few being identifiable to completely amorphous.

SP

Sandy peat

bolus is sandy to touch.

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LP

Loamy peat

bolus has obvious mineral particle content but no obvious sandiness to touch and is smooth, non-sticky when wet, and weakly coherent.

CP

Clayey peat

bolus has obvious fine mineral particle content, is sticky when wet, and is coherent.

On drying, peat may change irreversibly. GP

Granular peat

dominantly decomposed organic material, which has dried irreversibly to fine granules through exposure and drying and/or cultivation. Granules are about 1–2 mm in diameter and have granular or subangular blocky structure.

COARSE FRAGMENTS Coarse fragments may occur throughout the profile. Their abundance, size, shape, lithology and strength are described in exactly the same way as are coarse fragments on the surface (see page 139); in addition, their distribution is described.

Coarse fragment distribution U

Undisturbed

all fragments are remnants of the underlying bedrock and their orientation closely parallels that of the joint or bedding planes of the bedrock.

R

Reoriented

all fragments are remnants of the underlying bedrock but their orientation is not related to the joint or bedding planes of the bedrock.

S

Stratified

fragments occur in bands, usually parallel with the soil surface (excluding those parallel with joint or bedding planes of the bedrock). They may include materials other than those from the underlying bedrock.

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Soil Profile

D

Dispersed

fragments are scattered randomly throughout the soil and may be of mixed origin.

STRUCTURE Soil structure refers to the distinctness, size and shape of peds. A ped is an individual natural soil aggregate consisting of a cluster of primary particles. Peds are separated from adjoining peds by surfaces of weakness that are recognisable as natural voids or by the occurrence of cutans (Brewer 1960). Soil structure can only be described reliably in a relatively fresh vertical exposure or relatively undisturbed soil core, not from an auger boring. Vertical exposures that have been exposed for a long time (road cuttings, gullies) are unsuitable for the determination of structure that may alter due to daily or seasonal changes in moisture and temperature.

Grade of pedality Grade of pedality is the degree of development and distinctness of peds. In virtually all material that has structure, the surface of individual peds will differ in some way from the interior of peds. The degree of development expresses the relative difference between the strength of cohesion within peds and the strength of adhesion between adjacent peds. Determination of grade of structure in the field depends on the proportion of peds that hold together as entire peds when displaced and also on the ease with which the soil separates into discrete peds. Grade of pedality varies with the soil water status. It is important to record the soil water status of the described profile, and it is desirable to describe the grade of pedality at the soil water status most common for the horizon. Apedal soils have no observable peds and are divided into: G

13

Single grain

loose, incoherent13 mass of individual particles. When displaced, soil separates into ultimate particles.

Incoherent means that less than two-thirds of the soil material will remain united at the given moisture state without very small force (force 1, see ‘Consistence’ on page 186) having been applied.

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V

Massive

coherent.14 When displaced, soil separates into fragments (see page 181), which may be crushed to ultimate particles.

Pedal soils have observable peds and are divided into: W

Weak

peds indistinct and barely observable in undisplaced soil. When displaced, up to one-third of the soil material consists of peds, the remainder consisting of variable amounts of fragments and ultimate particles.

M

Moderate

peds well-formed and evident but not distinct in undisplaced soil. Adhesion between peds is usually firm or stronger. When displaced, more than one-third of the soil material consists of entire peds, the remainder consisting of broken peds, fragments and ultimate particles.

S

Strong

peds quite distinct in undisplaced soil. Adhesion between peds is usually firm or weaker. When displaced, more than two-thirds of the soil material consists of entire peds.

Size of peds The average least dimension of peds is used to determine the class interval. Use Figure 17 on pages 174–9 as a guide. The least dimension is the vertical dimension for platy structure; the horizontal dimension for prismatic, columnar, blocky and polyhedral peds; the maximum separation of convex faces for lenticular peds; and the diameter for granular peds. 1

<2 mm

2

2–5 mm

3

5–10 mm

14

Coherent means that two-thirds or more of the soil material will remain united at the given moisture state unless force is applied.

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Soil Profile

4 5 6 7 8 9

10–20 mm 20–50 mm 50–100 mm 100–200 mm 200–500 mm >500 mm

Type of pedality The types of structure are described below. Figure 17 illustrates these in diagrammatic form. PL

Platy

soil particles arranged around a horizontal plane and bounded by relatively flat horizontal faces with much accommodation to the faces of surrounding peds.

PR

Prismatic

soil particles arranged around a vertical axis and bounded by well-defined, relatively flat faces with much accommodation to the faces of surrounding peds. Vertices between adjoining faces are usually angular.

CO

Columnar

as for prismatic but with domed tops.

AB

Angular blocky

soil particles arranged around a point and bounded by six relatively flat, roughly equal faces. Re-entrant angles between adjoining faces are few or absent. There is usually much accommodation of ped faces to the faces of surrounding peds. Most vertices between adjoining faces are angular.

SB

Subangular similar to angular blocky except peds are bounded by flat blocky and rounded faces with limited accommodation to the faces of surrounding peds. Many vertices are rounded.

PO

Polyhedral

soil particles arranged around a point and bounded by more than six relatively flat, unequal, dissimilar faces. Re-entrant angles between adjoining faces are a feature. There is usually much accommodation of ped faces to the faces of surrounding peds. Most vertices are angular.

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Platy Peds 1 <2 mm thick

2 2 –5 mm

3 5 –10 mm

4 >10 mm

Figure 17 Ped size.

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Soil Profile

Prismatic and Columnar Peds 3

5–10 mm wide

4

5

20 –50 mm

6

50 –100 mm

7

>100 mm

Figure 17 (continued) Ped size. 175

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Australian Soil and Land Survey Field Handbook

Angular and Subangular Blocky Peds 2

2–5 mm wide

3

5 –10 mm

4

10 –20 mm

5

20 –50 mm

6

>50 mm

Figure 17 (continued) Ped size. 176

Soil Profile

Polyhedral Peds 2

2–5 mm wide

3

5 –10 mm

4

10 –20 mm

5

20 –50 mm

6

>50 mm

Figure 17 (continued) Ped size.

177

Lenticular Peds 2

2 –5 mm length of short axis

3

5 –10 mm

4

10 –20 mm

5

20 –50 mm

6

>50 mm

Figure 17 (continued) Ped size.

Soil Profile

Granular Peds 1

<2 mm diameter

2

2 –5 mm

3

5 –10 mm

4

>10 mm

Figure 17 (continued) Ped size.

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LE

Lenticular

soil particles arranged around an elliptical or circular plane and bounded by curved faces with much accommodation to the faces of surrounding peds. Most vertices are angular and acute.

GR

Granular

spheroidal with limited accommodation to the faces of surrounding peds.

CA

Cast

although faunal casts are strictly not peds, they may be described in a similar manner. They are formed from, or are deposited in, the O horizons or the soil solum and include: s excreta of soil fauna which may be discrete particles, for example insect faeces or the dense, coherent, globular forms of earthworm excreta. They are generally spherical or ovate in shape and have a strong conchoidal fracture. s soil masticated with salivary secretions into globular forms, for example, by ants, crickets, wasps.

Compound pedality Compound pedality occurs where large peds part along natural planes of weakness to form smaller peds, which may again part to smaller peds, and so on to the smallest or primary peds. Primary peds are the simplest peds occurring in soil material; they cannot be divided into smaller peds, but may be packed together to form compound peds of a higher level of organisation (Brewer 1964). The order of peds and relationship of one to the other is important and may be described as the larger peds parting to the smaller and further where necessary. For example, ‘strong 50–100 mm columnar, parting to moderate 20–50 mm prismatic, parting to moderate 10–20 mm angular blocky’. The word ‘parting’ and not ‘breaking’ is used. The term ‘breaking’ is used when soil is fractured along planes other than natural planes of weakness. 1 2 3

Largest peds (in the type of soil observation described), parting to Next size peds, parting to Next size peds, ... and further, if required, to the primary ped.

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Soil Profile

Clods and fragments Cultivated horizons (Ap horizons) often consist of artificial aggregates formed by cultivation or work being done on the soil. The distinction between artificial aggregates and peds can be difficult. In cultivated horizons, where the pedologist is confident the aggregates are natural peds, they should be recorded as such. If the pedologist is doubtful, or the aggregates are obviously artificial, they should be recorded as clods or fragments. CL FR

Clod Fragment

artificial aggregate with diameter 100 mm or more. artificial aggregate with diameter less than 100 mm.

FABRIC The definition of soil fabric in Australia is incomplete. The following description is adapted from Northcote (1979). Fabric describes the appearance of the soil material (under ×10 hand lens). Differences in fabric are associated with the presence or absence of peds, the lustre or lack of lustre of the ped surfaces, and the presence, size and arrangement of pores (voids) in the soil mass. The descriptions given below apply primarily to B horizons.

Earthy (or porous) fabric The soil material is coherent and characterised by the presence of pores (voids) and few, if any, peds. Ultimate soil particles (sand grains, for example) are coated with oxides and/or clays and are arranged (clumped) around the pores.

Sandy fabric The soil material is coherent, with few, if any, peds. The closely packed sand grains provide the characteristic appearance of the soil mass.

Rough-ped fabric Peds are evident, and characteristically more than 50% of the peds are roughfaced (i.e. they have relatively porous surfaces). (Rough-faced peds generally have less clearly defined faces than smooth-faced peds and the pedality of the soil may be questioned. However, if the soil mass is pressed gently, the characteristic size and shape of the soil aggregates will confirm its pedality.)

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Granular peds with common or many macropores are always rough-faced, but this condition varies in other ped forms.

Smooth-ped fabric Peds are evident, and characteristically more than 50% of them are dense and smooth-faced, although the degree of lustre may vary. E

R

Earthy Sandy (grains prominent) Rough-ped

S

Smooth-ped

G

CUTANS A cutan is a modification of the texture, structure or fabric at natural surfaces in soil materials; it arises from concentration of particular soil constitutents or in situ modification of the plasma. Cutans comprise any of the component substances of the soil material (Brewer 1964). Cutans may be observed in the field (a ×10 hand lens is usually necessary) but their nature is often difficult to determine unless a thin section is made. Hence, the following simple classification.

Types of cutans Z

Zero or no cutans

U

Unspecified

nature of cutans cannot be determined.

C

Clay skins

coatings of clay often different in colour from the matrix of the ped. They are frequently difficult to distinguish from stress cutans, which are not true coatings.

M

Mangans

coatings of manganese oxides or hydroxides. The material may have a glazed appearance and is very dark brown to black.

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Soil Profile

S

Stress cutans

in situ modifications of natural surfaces in soil materials due to differential forces such as shearing. They are not true coatings.

K

Slickensides

stress cutans with smooth striations or grooves.

O

Other cutans

may be composed of iron oxides, organic matter, calcium carbonate or gypsum.

Abundance of cutans 0 1 2 3

No cutans Few Common Many

0 <10% of ped faces or pore walls with cutans. 10–50% of ped faces or pore walls with cutans. >50% of ped faces or pore walls with cutans.

Distinctness of cutans This refers to the ease and certainty with which a cutan is identified. Distinctness relates to thickness and to the colour contrast with the adjacent material; it may change markedly with moisture content. F

Faint

evident only on close examination with ×10 magnification. Little contrast with adjacent material.

D

Distinct

can be detected without magnification. Contrast with adjacent material is evident in colour, texture or other properties.

P

Prominent

conspicuous without magnification when compared with a surface broken through the soil. Colour, texture or some other property contrasts sharply with properties of the adjacent material, or the feature is thick enough to be conspicuous.

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VOIDS This is a general term for pore space and other openings in soils not occupied by solid mineral matter. The most important are cracks (planar voids) and pores, which are approximately circular in cross-section.

Cracks Width 1 2 3 4 5

Fine Medium

<5 mm 5–10 mm

Coarse Very coarse Extremely coarse

10–20 mm 20–50 mm >50 mm

Pores Pores are divided into: Micropores less than 0.075 mm diameter Macropores greater than 0.075 mm diameter Only macropores can be seen with the naked eye (Figure 18). All visible pores, holes and tubes within peds, clods, fragments or apedal soil are recorded in the classes below.

Abundance of macropores There are two groups: Very fine and fine macropores (less than 2 mm diameter) 0

No very fine or fine macropores

1

Few Common Many

2 3

<1 per 100 mm2 1–5 per 100 mm2 >5 per 100 mm2

(10 mm × 10 mm) (10 mm × 10 mm) (10 mm × 10 mm)

Medium and coarse macropores (greater than 2 mm diameter) 0

No medium or coarse macropores

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Soil Profile

Size of Macropores Very fine <1 mm

Fine 1–2 mm

Medium 2–5 mm

Coarse >5 mm

Figure 18 Size of macropores.

5

Few Common

<1 per 0.01 m2 1–5 per 0.01 m2

(100 mm × 100 mm) (100 mm × 100 mm)

6

Many

>5 per 0.01 m2

(100 mm × 100 mm)

4

Diameter of macropores Use Figure 18 as a guide to average diameter. 1 2 3 4

Very fine Fine Medium Coarse

0.075–1 mm 1–2 mm 2–5 mm >5 mm 185

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SOIL WATER STATUS Give soil water status of the soil at the time of description (Table 30). It may also be relevant to note the weather conditions immediately prior to examination of the soil if these are known; for example a soil may be wet because of local rain or from seepage. The following guidelines may be used as a crude approximation of soil water status: s Dry is below wilting point. Material becomes darker or has lower colour value when moistened. s Moderately moist is the drier half of the available moisture range. s Moist is the wetter half of the available moisture range. s Wet is at, or exceeding, field capacity. Will wet and/or stick to fingers when moulded. These guidelines may not apply with sodic 2:1 clays, as, for example, they may be moderately moist but below wilting point.

CONSISTENCE Consistence refers to the strength of cohesion and adhesion in soil. Strength will vary according to soil water status. Note that soil water status must be recorded with strength. Table 30 Soil water status Behaviour of soils subjected to field test Soil water status

Sands, sandy loams

Loams

Clay loams, clays

D

Dry

will flow through fingers or fragments will powder.

will not ball when squeezed in hand. Fragments will powder.

will not ball when squeezed in hand. Fragments will break to smaller fragments or peds.

T

Moderately moist

appears dry. Ball will not hold together.

forms crumbly ball on squeezing in hand.

will ball. Will not ribbon.

M

Moist

forms weak ball but breaks easily.

will ball. Will not ribbon.

will ball. Will ribbon easily.

W

Wet

ball leaves wet outline on hand when squeezed, or is wetter.

ball leaves wet outline on hand when squeezed, or is wetter. Sticky.

ball leaves wet outline on hand when squeezed, or is wetter. Sticky.

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Soil Profile

Strength Strength of soil is the resistance to breaking or deformation. Strength is determined by the force just sufficient to break or deform a 20 mm diameter piece of soil when a compressive shearing force is applied between thumb and forefinger. The 20 mm piece of soil may be a ped, part of a ped, a compound ped or a fragment.

Force15 0

Loose

no force required. Separate particles such as loose sands.

1

Very weak

very small force, almost nil.

2

Weak

small but significant force.

3

Firm

moderate or firm force.

4

Very firm

strong force but within power of thumb and forefinger.

5

Strong

beyond power of thumb and forefinger. Crushes underfoot on hard, flat surface with small force.

6

Very strong

crushes underfoot on hard, flat surface with full body weight applied slowly.

7

Rigid

cannot be crushed underfoot by full body weight applied slowly.

Stickiness Stickiness is determined on wet soil by pressing the wet sample between thumb and forefinger and then observing the adherence of the soil to the fingers.

15

Forces 0 to 5 are equivalent to the following dry consistence classes in the USDA soil survey manual (Soil Survey Staff 1951): 0 1 2

Loose Soft Slightly hard

3 4 5

Hard Very hard Extremely hard

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0

Non-sticky

little or no soil adheres.

1

Slightly sticky

soil adheres to thumb and forefinger but is not stretched notably and comes off rather cleanly.

2

Moderately sticky

soil adheres to thumb and forefinger and tends to stretch rather than pull free of fingers.

3

Very sticky

soil adheres strongly to thumb and forefinger and stretches notably.

Type of plasticity The type of plasticity refers to the degree to which the either the consistence, field texture or both properties of a soil suggest the amount of clay-sized particles it contains (Butler 1955). It may be identified by determining two field textures: one after an initial 1 to 2 minute working of the soil sample, and another after a prolonged 10 minute kneading. The change in field texture from the initial to the prolonged working of the soil sample indicates the type of plasticity. Field texture change after 10 minute kneading S

Superplastic

N

Normal plasticity

U

Subplastic Strongly subplastic

T

decreases one or more field texture groups of Northcote (1979). negligible change. increases one to two field texture groups. increases two or more field texture groups.

Degree of plasticity Plasticity is the ability to change shape and retain the new shape after the stress is removed. The degree of plasticity given below applies only to normal plasticity. The degree of plasticity is determined at the soil moisture content used for field texturing (i.e. just below sticky point). The soil is rolled between the palms of the hand and, if possible, 40 mm long rolls are formed. The rolls are dangled

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Soil Profile

from the thumb and forefinger. Plasticity is determined on the following scale of behaviour of rolls of varying thickness. Dimensions and behaviour of rolls Length Diameter Behaviour 0

Non-plastic 40 mm

6 mm

will not form.

1

Slightly plastic

40 mm

6 mm

will form and will support its own weight.

40 mm

4 mm

will form but will not support its own weight.

Moderately 40 mm plastic

4 mm

will form and will support its own weight.

40 mm

2 mm

will form but will not support its own weight.

Very plastic 40 mm

2 mm

will form and will support its own weight.

2

3

CONDITION OF SURFACE SOIL WHEN DRY Many surface soils have a characteristic appearance when dry. Because surface conditions are often relevant to the use of the soil and indicative of particular kinds of soil, every effort should be made to observe the surface condition in the dry state. The following conditions are not necessarily mutually exclusive: G

Cracking

cracks at least 5 mm wide and extending upwards to the surface or to the base of any plough layer or thin (<0.03 m) surface horizon.

M

Self-mulching

strongly pedal loose surface mulch forms on wetting and drying. Peds commonly less than 5 mm in least dimension.

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L

Loose

incoherent16 mass of individual particles or aggregates. Surface easily disturbed by pressure of forefinger.

S

Soft

coherent17 mass of individual particles or aggregates. Surface easily disturbed by pressure of forefinger.

F

Firm

coherent17 mass of individual particles or aggregates. Surface disturbed or indented by moderate pressure of forefinger.

H

Hard setting

compact, hard, apparently apedal condition forms on drying but softens on wetting. When dry, the material is hard below any surface crust or flake that may occur, and is not disturbed or indented by pressure of forefinger.

C

Surface crust

distinct surface layer, often laminated, ranging in thickness from a few millimetres to a few tens of millimetres, which is hard and brittle when dry and cannot be readily separated from, and lifted off, the underlying soil material.

X

Surface flake

thin, massive surface layer, usually less than 10 mm thick, which on drying separates from, and can be readily lifted off, the soil below. It usually consists mainly of dispersed clay, and may become increasingly fragile as the soil dries.

Y

Cryptogam surface

thin, more or less continuous crust of biologically stabilised soil material usually due to algae, liverworts and mosses.

16

Incoherent means that less than two-thirds of the soil material, whether composed of peds or not, will remain united at the given moisture state without very small force (force 1, see ‘Consistence’ on page 186) having been applied.

17

Coherent means that two-thirds of the soil material, whether composed of peds or not, will remain united at the given moisture state unless force is applied.

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Soil Profile

T

Trampled

soil that has been extensively trampled under dry conditions by hoofed animals.

P

Poached

soil that has been extensively trampled under wet conditions by hoofed animals.

R

Recently cultivated

effect of cultivation is obvious.

Z

Saline

surface has visible salt, or salinity is evident from the absence or nature of the vegetation or from soil consistence. These conditions are characterised by their notable difference from adjacent non-saline areas.

O

Other

WATER REPELLENCE Water repellence of some soils, usually sandy, is caused by a series of longchain polymethylene waxes, made up of acids, alcohols and esters, attached to the sand grains (Ma’shum et al. 1988). These soils occur Australia-wide but are more widespread in southern Australia (McGhie and Posner 1980; Wetherby 1984). Degree of repellence is assessed by determining the concentration of ethanol required to wet the sand in 10 seconds (King 1981). An abbreviated form of this method is recommended for routine field situations. N

Non water repellent

water is absorbed into soil in 10 seconds or less.

R

Water repellent

water takes greater than 10 seconds and 2 Molar ethanol takes 10 seconds or less to be absorbed into soil.

S

Strongly water repellent

2 Molar ethanol takes greater than 10 seconds to be absorbed into soil.

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Note: Soil temperature at testing should be between 15ºC and 25ºC. Higher temperatures will increase, and lower decrease, rates of absorption. Industrialgrade methylated spirits, available from chemists, at a concentration of 23.9 mL per 200 mL water can be substituted for the 2 Molar ethanol to obtain approximate values.

PANS A pan is an indurated and/or cemented soil horizon.

Cementation of pan Place a 30 mm diameter piece of the pan in water for 1 hour. If it slakes, it is uncemented; if not, it is cemented. The degree of cementation is assessed on the following scale after the 1 hour soaking in water. 0

Uncemented

slakes.

1

Weakly cemented

can be crushed between thumb and forefinger.

2

Moderately cemented

beyond power of thumb and forefinger. Crushes underfoot on hard, flat surface with weight of average person (80 kg) applied slowly.

3

Strongly cemented cannot be crushed underfoot by weight of average person applied slowly. Can be broken by hammer.

4

Very strongly cemented

cannot be broken by hammer, or only with extreme difficulty.

Type of pan Z

Zero or no pan

K

Calcrete

any cemented, terrestrial carbonate accumulation that may vary significantly in morphology and degree of cementation. Also known as carbonate pan, calcareous pan, caliche, kunkar, secondary

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Soil Profile

limestone, travertine. All show slight to strong effervescence with 1 Molar HCl. L

Silcrete

strongly indurated siliceous material cemented by, and largely composed of, forms of silica, including quartz, chalcedony, opal and chert.

R

Red-brown hardpan

earthy pan, which is normally reddish brown to red with dense yet porous appearance; it is very hard, has an irregular laminar cleavage and some vertical cracks, and varies from less than 0.3 m to over 30 m thick. Other variable features are bedded and unsorted sand and gravel lenses; wavy black veinings, probably manganiferous; and, less commonly, off-white veins of calcium carbonate. (The presence of calcium carbonate is not common and the red-brown hardpan in which it occurs may be relatively brittle and finely laminar.) The red-brown hardpan is usually present below the soil profile and is not a feature of any particular soil group. (It has some similarity with other silica pans such as duripans of arid climates). In many instances, it is not known if the red-brown hardpan is a paleosol or a cemented sediment (Wright 1983). If thought to be the latter, it may be described as a substrate material (page 205).

D

Duripan

earthy pan so cemented by silica that dry fragments do not slake in water and are always brittle, even after prolonged wetting. (Described by Soil Survey Staff 1975.)

F

Fragipan

earthy pan, which is usually loamy. A dry fragment slakes in water. A wet fragment does not slake in water but has moderate or weak brittleness. Fragipans are more stable on exposure than overlying or underlying horizons. (Described by Soil Survey Staff 1975.) 193

Australian Soil and Land Survey Field Handbook

N

Densipan

earthy pan, which is very fine sandy (0.02– 0.05 mm). Fragments, both wet and dry, slake in water. Densipans are less stable on exposure than overlying or underlying horizons. (Described by Smith et al. 1975.)

I

Thin ironpan

commonly thin (2–10 mm), black to dark reddish pan cemented by iron, iron and manganese, or iron–organic matter complexes. Rarely 40 mm thick. Has wavy or convolute form and usually occurs as a single pan. This is a placic horizon (described by Soil Survey Staff 1975, page 33).

E

Ferricrete

indurated material rich in hydrated oxides of iron (usually goethite and hematite) occurring as cemented nodules and/or concretions, or as massive sheets. This material has been commonly referred to in local usage around Australia as laterite, duricrust or ironstone.

A

Alcrete (bauxite)

indurated material rich in aluminium hydroxides. Commonly consists of cemented pisoliths and usually known as bauxite.

M

Manganiferous pan

indurated material dominated by oxides of manganese.

T

Ortstein

horizon strongly cemented by iron and organic matter. It has marked local variability in colour, both laterally and vertically. It may occur in the B horizon of podzols.

C

Organic pan

horizon relatively high in organic matter but low in iron. It is relatively thick and weakly to strongly cemented by aluminium and usually becomes progressively more cemented with depth. It is usually relatively uniform in appearance laterally. It is commonly the B horizon of humus podzols, where it is often known as coffee rock or sandrock. 194

Soil Profile

V

Cultivation pan

O

Other pans

subsurface soil horizon having higher bulk density, lower total porosity, and lower permeability to both air and water than horizons directly above and below as a result of cultivation practices. (After Morse et al. 1987.)

Continuity of pan C

Continuous

extends as a layer with little or no break across 1 m or more.

D

Discontinuous

broken by cracks but original orientation of fragments is preserved.

B

Broken

broken by cracks and fragments are disoriented.

Structure of pan V

Massive

no recognisable structure.

S

Vesicular

sponge-like structure having large pores, which may or may not be filled with softer material.

C

Concretionary

spheroidal concretions cemented together.

N

Nodular

nodules of irregular shape cemented together.

L

Platy

plate-like units cemented together.

R

Vermicular

worm-like structure and/or cavities.

SEGREGATIONS OF PEDOGENIC ORIGIN This refers to discrete segregations that have accumulated in the soil because of the concentration of some constituent, usually by chemical or biological action. 195

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Segregations may be relict or formed in situ by current pedogenic processes.

Abundance of segregations Use Figure 11 as a guide (see page 141). 0 1 2 3 4 5

No segregations Very few Few Common Many Very many

0 <2% 2–10% 10–20% 20–50% >50%

Nature of segregations U K Y M N F A S Z H G L E O

Unidentified Calcareous (carbonate) Gypseous (gypsum) Manganiferous (manganese) Ferromanganiferous (iron–manganese) Ferruginous (iron) Aluminous (aluminium) Sulfurous (sulfur) (e.g. in acid sulfate soils) Saline (visible salt) Organic (humified, well-decomposed organic matter) Ferruginous–organic (iron–organic matter) Argillaceous (clayey) Earthy (dominantly non-clayey) Other

Form of segregations C

Concretions

spheroidal mineral aggregates. Crudely concentric internal fabric can be seen with naked eye. Includes pisoliths and ooliths. 196

Soil Profile

N

Nodules

irregular, rounded mineral aggregates. No concentric or symmetric internal fabric. Can have hollow interior.

F

Fragments

broken pieces of segregations.

X

Crystals

single or complex clusters of crystals visible with naked eye or ×10 hand lens.

S

Soft segregations

finely divided soft segregations. They contrast with surrounding soil in colour and composition but are not easily separated as discrete bodies. Boundaries may be clearly defined or diffuse.

V

Veins

fine (<2 mm wide) linear segregations.

R

Root linings

linings of former or current root channels.

T

Tubules

medium or coarser (>2 mm wide) tube-like segregations, which may or may not be hollow.

L

Laminae

planar, plate-like or sheet-like segregations.

Size of segregations Approximately equidimensional segregations (concretions, nodules) are measured in the greatest dimension. Segregations where one dimension is much greater than the other two (tubules, root linings, veins, laminae) are measured in the least dimension. 1 2 3 4 5

Fine Medium Coarse Very coarse Extremely coarse

<2 mm 2–6 mm 6–20 mm 20–60 mm >60 mm

Strength of segregations Strength may be recorded where appropriate. 197

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1 2

Weak Strong

can be broken between thumb and forefinger. cannot be broken between thumb and forefinger.

Magnetic attributes of segregations N M

Non-magnetic Magnetic

not attracted onto surface of hand-held magnet. attracted onto surface of hand-held magnet.

EFFERVESCENCE OF CARBONATE IN FINE EARTHa N

Non-calcareous

S

Slightly calcareous slightly audible but no visible effervescence.

M

Moderately calcareous

H

Highly calcareous moderate visible effervescence.

V

Very highly calcareous

no audible or visible effervescence.

audible and slightly visible effervescence.

strong visible effervescence.

a Using two or three drops of 1 Molar HCl.

FIELD pH The soil pH is determined in the field using a field pH kit based on the specifications of Raupach and Tucker (1959). Estimate to 0.5 of a unit. Portable pH meters may also be used. Record depth at which pH is determined, in metres. The pH may be measured either: s by horizons, or s where horizons are thick (>0.5 m) and horizon boundaries are diffuse, at selected intervals down the profile. This system gives useful data in some soils when important pH changes may occur independently of visible horizon changes (e.g. the change from alkaline to strongly acid conditions in some cracking clays). 198

Soil Profile

ROOTS Record the presence of roots observed in each horizon in areas 100 mm square on a cleaned exposure face.

Root size 1

Diameter <1 mm 1–2 mm 2–5 mm >5 mm

Very fine Fine Medium Coarse

2 3 4

Root abundance Table 31 Root abundance Number of roots per 0.01 m2 (100 mm × 100 mm) Very fine and fine roots

Medium and coarse roots

0

No roots

0

0

1

Few

1–10

1–2

2

Common

10–25

2–5

3

Many

25–200

>5

4

Abundant

>200

>5

BOUNDARIES BETWEEN HORIZONS Boundary distinctness Width of boundary S A C G D

Sharp Abrupt Clear Gradual Diffuse

<5 mm 5–20 mm 20–50 mm 50–100 mm >100 mm 199

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Boundary shape S W

Smooth Wavy

almost a plane surface. undulations with depressions wider than they are deep.

I

Irregular

T

Tongued

undulations with depressions deeper than they are wide. depressions considerably deeper than they are wide.

B

Broken

discontinuous.

SOIL WATER REGIME Traditional approaches to soil drainage do not adequately differentiate between hydrological setting and permeability of the material of the profile. For example, a very permeable, coarse-textured soil occurring in a wet depression would have to be classed as very poorly drained. Hence, there is a need to consider permeability, which refers to the potential of a soil to transmit water internally, and drainage, which refers to the rapidity and extent of water removal from the soil profile or site. Both these aspects of internal drainage may be difficult to assess in the field, and cannot be based solely on profile morphology. Mottling may, but not always, reflect drainage status, since mottling may be a relict feature. Vegetation and topography may be useful guides. The concepts of permeability and drainage given below are largely based on Canada Soil Survey Committee (1978).

Soil permeability Permeability is independent of climate and drainage, and – as applied to a soil – is controlled by the potential to transmit water (saturated hydraulic conductivity, Ks) of the least permeable layer in the soil. Therefore it is inferred from attributes of the soil such as structure, texture, porosity, cracks and shrink–swell properties. In the classes given below, the rate of transmission of water in the profile is based on the assumption that loss by evapotranspiration is minimal. The Ks ranges are compatible with those of Nowland in Canada, as reported by McKeague et al. (1982).

200

Soil Profile

1

Very slowly permeable Ks range: <5 mm/day Drainage time: months

2

Slowly permeable

3

Moderately permeable

vertical transmission of water in the least permeable horizon is very slow; the profile would take a month or more after thorough wetting to reach field capacity if there were no obstructions to movement from the profile. Structure may vary, but cracks or spaces between peds when dry close on wetting. Texture is usually clay or silty clay, and there are no pores visible (with a hand lens) that could conduct water when wet.

vertical transmission of water in the least permeable horizon is slow; the profile Ks range: 5–50 mm/day would take a week or more after thorough wetting to reach field capacity if there were Drainage time: weeks no obstructions to movement from the profile. Structure may vary, usually from massive to moderate grade. Texture is usually clay or silty clay, and there will be few pores visible (with a hand lens) that conduct water when wet. If texture is coarser, the interparticle voids are filled with fine mineral.

Ks range: 50–500 mm/ day Drainage time: days

vertical transmission of water in the least permeable horizon is such that the profile would take no more than 1–5 days after a thorough wetting to reach field capacity if there were no obstructions to water movement from the profile. The soil may vary in structure but grade is usually at least moderate, and blocky or polyhedral peds are common. If massive, the soil material is always porous. The pores and channels that remain open when wet are clearly visible with a hand lens.

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4

Highly permeable

vertical transmission of water in the least permeable horizon is such that the profile Ks range: >500 mm/day would take no more than 1–12 hours after a thorough wetting to reach field capacity if Drainage time: hours there were no obstructions to water movement from the profile. Horizons have large, continuous and clearly visible connecting pores and cracks that do not close with wetting. Texture is usually sandy and nodules or gravel are commonly present. Soil horizons are usually apedal, but some medium-textured to finetextured soils with strong granular structure or cementation of aggregates can be highly permeable.

Although Ks data are limited for Australian soils, values for some well-known soils may be found in Bonell et al. (1983), Talsma (1983) and Williams (1983).

Drainage Drainage is a useful term to summarise local soil wetness conditions; that is, it provides a statement about soil and site drainage likely to occur in most years. It is affected by several attributes, both internal and external, that may act separately or together. Internal attributes include soil structure, texture, porosity, hydraulic conductivity and water-holding capacity, while external attributes are source and quality of water, evapotranspiration, gradient and length of slope, and position in the landscape. 1

Very poorly drained

water is removed from the soil so slowly that the watertable remains at or near the surface for most of the year. Surface flow, groundwater and subsurface flow are major sources of water, although precipitation may be important where there is a perched watertable and precipitation exceeds evapotranspiration. Soils have a wide range in texture and depth, and often occur in

202

Soil Profile

depressed sites. Strong gleying and accumulation of surface organic matter are usually features of most soils. 2

Poorly drained

water is removed very slowly in relation to supply. Subsurface and/or groundwater flow, as well as precipitation, may be a significant water source. Seasonal ponding, resulting from runon and insufficient outfall, also occurs. A perched watertable may be present. Soils have a wide range in texture and depth; many have horizons that are gleyed, mottled, or possess orange or rusty linings of root channels. All horizons remain wet for several months.

3

Imperfectly drained

water is removed only slowly in relation to supply. Precipitation is the main source if available water storage capacity is high, but subsurface flow and/or groundwater contribute as available water storage capacity decreases. Soils have a wide range in texture and depth. Some horizons may be mottled and/or have orange or rusty linings of root channels, and are wet for several weeks.

4

Moderately well-drained

water is removed from the soil somewhat slowly in relation to supply, due to low permeability, shallow watertable, lack of gradient, or some combination of these. Soils are usually medium to fine in texture. Significant additions of water by subsurface flow are necessary in coarse-textured soils. Some horizons may remain wet for as long as one week after water addition.

5

Well-drained

water is removed from the soil readily but not rapidly. Excess water flows downward

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Australian Soil and Land Survey Field Handbook

readily into underlying, moderately permeable material or laterally as subsurface flow. The soils are often medium in texture. Some horizons may remain wet for several days after water addition. 6

Rapidly drained

water is removed from the soil rapidly in relation to supply. Excess water flows downward rapidly if underlying material is highly permeable. There may be rapid subsurface lateral flow during heavy rainfall provided there is a steep gradient. Soils are usually coarse-textured, or shallow, or both. No horizon is normally wet for more than several hours after water addition.

204

S U B S T R AT E J.G. Speight and R.F. Isbell

This chapter deals with materials and masses of earth (see pages 211 and 216) or rock that do not show pedological development. They are not soils, but typically underlie them. The substrate includes the R horizon and that part of the C horizon that shows no pedological development (page 151), but excludes the solum, buried soil horizons (including D horizons), and pans. The substrate beneath a soil profile may or may not be the parent material of the soil. The properties of the substrate should be described as objectively as possible. The first group of properties refers to the material or substance in an intact state, as would be seen in a hand-sized specimen without cracks. Such properties serve to identify the type of rock, such as sandstone, or unconsolidated material, such as clay. A second group of properties comprising spacing of discontinuities, alteration and mass strength refers to substrate masses. These require observations of areas of greater dimensions. Types of substrate mass are classified mainly according to their inferred origin. Examples are alluvium, parna, ferricrete and saprolite. The substrate should be assessed at the point of the soil profile observation or as close to it as may be practicable. Large vertical exposures of the substrate may reveal the spatial variation of substrate features.

Type of observation of substrate material P E

Soil pit Existing vertical exposure

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C A O

Undisturbed soil core Auger boring Outcrop, where presumed continuous with substrate

Distance Estimate the distance in metres of the point of observation of substrate material from the point of soil observation.

Confidence that substrate is parent material The observer should state the degree of confidence that the observed substrate material is the parent material of the observed soil profile or the major part of that profile (i.e. of the B horizon). N D P A

Not parent material Dubious, doubtful Probable Almost certain or certain

Depth Measure or estimate, in metres, the depth of the point of observation of substrate material below the land surface.

PROPERTIES OF SUBSTRATE MATERIAL The properties in this section refer to intact hand-sized samples or very small areas of outcrop. In many cases it will be necessary to use a ×10 hand lens to determine some of them.

Grain size It is informative to estimate the size of the most common particles of a substrate material whether the material is thought to be of sedimentary, metamorphic or igneous origin.

206

Substrate

1

<0.06 mm18

silt- or clay-sized; grains not visible (e.g. chert, shale, basalt, silt, coal).

2

0.06–2 mm18

sand-sized; grains visible (e.g. sand, sandstone, dolerite, porphyry, sandy tuff, graywacke, microgranite, schist, quartzite).

3

>2 mm

gravel-sized (e.g. gravel, conglomerate, breccia, pebbles, cobbles, stones, boulders, pegmatite, granite, agglomerate).

Texture F

Fragmental

consisting of mineral or rock particles that are broken or abraded.

X

Crystalline (non-porphyritic)

consisting of interlocking mineral crystals.

P

Porphyritic

crystalline, with individual larger crystals in a matrix of much smaller crystals or glass.

A

Amorphous

without visible crystalline or fragmental texture, even through a hand lens.

Structure V

Massive

no recognisable structure.

S

Vesicular

sponge-like structure having large pores, which may or may not be filled with softer material.

18

As shown by Figure 15, page 162, these size grade limits agree with the scale of Wentworth (1922), adopted by the United States National Research Council (Pettijohn 1957) and the American Geophysical Union (Lane et al. 1947), and with that of the Massachusetts Institute of Technology, also adopted by the British Standards Institution (1975) and the Standards Association of Australia (1977). The 0.06 mm boundary criterion (strictly 0.063 mm) separating sand and silt differs markedly from the value 0.02 mm of the International scheme (proposed originally by Atterberg, 1905, and accepted by the International Society of Soil Science); the 0.05 mm value of the United States Department of Agriculture (Soil Survey Staff 1975); and the 0.075 mm value of the Unified Soil Classification (US Army Corps of Engineers 1953).

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C

Concretionary

spheroidal concretions cemented together.

P

Platy

plate-like units cemented together.

R

Vermicular

worm-like structure and/or cavities.

B

Bedded

with planar surfaces marking successively deposited layers.

F

Fissile

easily split along closely spaced parallel planes.

L

Foliated

planar arrangement of textural or structural textures.

Porosity 0 1 2

Non porous; dense Slightly porous Porous

Mineral composition Make provision for recording one dominant mineral and one or two minor minerals, as identified by inspection of the hand specimen. Q F M D L K S G C Y

Quartz Feldspar Mica Dark minerals Clays (argillaceous) Carbonates (react with 1 Molar HCl) Sesquioxides Glauconite Carbonaceous material Gypsum

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Substrate

Table 32 Field estimation of strength class of intact rock material by cutting or striking with knife, pick or hammera Strength

Knife

Pick

Hammer (single blow)

VW

Very weak rock (1–25 MPa)

Deep cut

Crumbles

Flattened or powdered

W

Weak rock (25–50 MPa)

Shallow cut or scratch

Indents deeply

Shattered into many small fragments

M

Moderately strong rock (50–100 MPa)

Nil or slight mark

Indents shallowly

Breaks readily into a few large and some small fragments

S

Strong rock (100–200 MPa)

Nil

Nil

Breaks into one or two large fragments

VS

Very strong rock (>200 MPa)

Nil

Nil

Nil

a This table was developed through correspondence with MJ Selby (see Piteau 1971; Selby 1980; Hoek and Bray 1977, page 99; and compare with Anon. 1977).

Strength of material The strength of a specimen of soil substrate material may be crudely estimated in the field by striking it with the head-end or the pick-end of a geological hammer or by trying to cut it with a knife, and then referring to Table 32. These estimates refer to the unconfined (or uniaxial) compressive strength. The strength is that of the intact material rather than that of the mass, the strength of which has generally been reduced by the development of fractures and other phenomena.

Lithological type of substrate material The properties above will key out many of the rock types and unconsolidated materials listed in Tables 33 and 34. Record the rock type only if it is definitely known or is confidently presumed. An alphabetic checklist for types of substrate material, both rocks and unconsolidated materials, is given in Table 35. Only the more common materials are listed. Others can be recorded in free format.

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Table 33 Unconsolidated material classificationa Non-volcanic Without significant carbonate

Volcanic

Grain size class

Diameter (mm)

With significant carbonate

Very coarse grained

>60

BO SN CB

Boulders Stones Cobbles

BB

Bombs (or blocks)

Coarse grained

2–60

GV

Gravel

SK

Scoria (or lapilli)

Medium grained

0.06b –2

S

Sand

AS

Volcanic ash (sandy)

Fine grained

0.002–0.06

Z

Silt

AF

Volcanic ash (fine)

Very fine grained

<0.002

C

Clay

KS

ML

Calcareous sand

Marl

a Material that is loose, plastic, or does not exceed the strength of ‘Very weak rock’ in Table 32; can be dug with hand tools. b See footnote 18, page 207.

PROPERTIES OF SUBSTRATE MASSES These properties generally require observation of a near-vertical face 1 m2 or more in area.

Spacing of discontinuities Physical weathering opens up fissures or joints that reduce the strength of the rock mass relative to that of the intact rock material. These fissures generally increase in number towards the land surface. The following categories of discontinuity spacing apply (Deere 1968; Selby 1982): S M B F C

>3 m 1–3 m 300 mm – 1 m

solid; virtually unjointed. massive; few joints. blocky; moderately jointed.

50–300 mm <50 mm

fractured; intensely jointed. crushed or shattered.

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Substrate

Alteration Substrate materials may be so extensively altered (as in deep weathering profiles) that it may be difficult or impossible to determine their original nature. Certain constituents may be either depleted or enriched. Thus, in many laterite profiles, some horizons are ferruginised, partially ferruginised and partially kaolinised, and the pallid zone kaolinised. Silicification may also be associated with deep weathering profiles although not exclusively so; for instance, some limestones may be variably silicified. In contrast, calcification, which is widespread in parts of southern Australia, is not usually associated with deep weathering. F

Ferruginised

iron enriched.

L

Kaolinised

S

Silicified Calcified Other

clay enriched, usually pale coloured (e.g. the pallid zone of a laterite profile). silica enriched. calcium carbonate enriched. deeply weathered but no specific nature.

K O

In some instances more than one type of alteration may be present (e.g. the mottled zone of a laterite profile may be both ferruginised and kaolinised). Where both types of alteration occur, record both.

Mass strength The mass strength of bodies of earth or rock affects tree growth, land-forming processes and engineering works, but it is difficult to measure. Direct tests of mass strength are not proposed here. However, broad strength classes contribute to defining types of substrate mass. Table 36 orders types of substrate mass in terms of their unconfined compressive strength, using the same strength classes as in Table 32. In engineering usage, masses with an unconfined compressive strength less than 1.0 MPa (or 1.25 MPa; Anon. 1977) correspond to ‘soil’ or ‘earth’. The engineering definitions of soil and rock are given by Terzaghi and Peck (1967): ‘Soil is a natural aggregate of mineral grains that can be separated by such gentle mechanical means as agitation in water. Rock, on the other hand, is a natural

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Table 34 Rock type classification Developed from a classification by Dearman (Anon. 1977) and that in BW 5930 1981 (British Standards Institution 1981).

Texture

Fragmental (cryptocrystalline or amorphous)

Structure

CONGLOMERATE (grains rounded) Very coarse (Rudaceous) BRECCIA (grains angular) 2.0 mm

Grain size

Coarse (Arenaceous)

SANDSTONE QUARTZ SANDSTONE (mainly quartz) ARKOSE (mainly feldspar)

0.06 mm Fine (Argillaceous)

GRAYWACKE SILTSTONE MUDSTONE SHALE (fissile)

0.002 mm Very fine (Argillaceous)

Amorphous or cryptocrystalline

CLAYSTONE

Carbonate

LIMESTONE (CaCO3) DOLOMITE (CaMg (CO3)2)

Quartz, feldspar, rock fragments

Volcanic rock (juvenile)

Evaporite or organic matter

AGGLOMERATE (grains rounded) CALCIRUDITE VOLCANIC BRECCIA (grains angular)

HALITE (NaCl) ANHYDRITE (CaSO4)

CALCARENITE

CALCAREOUS MUDSTONE

Dominant mineral grains

Bedded

GYPSUM (CaSO4, 2H2O ) TUFF

CALCILUTITE MARL

CHERT, JASPER

COAL

Sedimentary rocks Genetic group Detrital (Sd)

212

Pyroclastic (Sp)

Chemical (Sc)

Substrate

Crystalline (or amorphous) Foliated Quartz, feldspar, mica

Massive (Various)

Quartz, potassic and sodic feldspar

Potassic Sodic feldspar, Calcic feldspar, dark minerals feldspar, (little quartz) (little quartz) dark minerals PEGMATITE

GNEISS

GRANITE

MIGMATITE

ADAMELLITE

SYENITE

PYROXENITE (mainly pyroxene) DIORITE

GABBRO

MICRODIORITE

DOLERITE

ANDESITE

BASALT

GRANODIORITE MARBLE (carbonate) QUARTZITE SCHIST

GRANULITE HORNFELS

Dark minerals

PERIDOTITE (mainly olivine)

MICROGRANITE MICROSYENITE

APLITE QUARTZ PORPHYRY (porphyritic texture)

PORPHYRY (porphyritic texture)

RHYOLITE

TRACHYTE

AMPHIBOLITE PHYLLITE

SLATE (strongly fissile)

SERPENTINITE GREENSTONE

MYLONITE (intensely deformed)

Metamorphic rocks (Me)

VOLCANIC GLASS

Igneous rocks (Ig) Felsic

Mafic

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Table 35 Alphabetical checklist of lithological type of rock material and unconsolidated materiala AD AG AC AM AN AH AP AR AF AS BA BB BR KA KM KS KL KR KC CH C CO CG CU SD DI DR DM FC GA GS GN GD GR GV GW GE GY HA HO IG

Adamellite Agglomerate Alcrete (bauxite) Amphibolite Andesite Anhydrite Aplite Arkose Ash (fine) Ash (sandy) Basalt Bombs (volcanic) Breccia Calcarenite Calcareous mudstone Calcareous sand Calcilutite Calcirudite Calcrete Chert Clay Coal Conglomerate Consolidated rock (unidentified) Detrital sedimentary rock (unidentified) Diorite Dolerite Dolomite Ferricrete Gabbro Gneiss Granite Granodiorite Granulite Gravel Graywacke Greenstone Gypsum Halite Hornfels Igneous rock (unidentified)

(Ig) (Sp) (Sc) (Me) (Ig) (Sc) (Ig) (Sd) (Uc) (Uc) (Ig) (Uc) (Sd) (Sd) (Sd) (Uc) (Sd) (Sd) (Sc) (Sc) (Uc) (Sc) (Sd)

(Ig) (Ig) (Sd) (Sc) (Ig) (Me) (Ig) (Ig) (Me) (Uc) (Sd) (Me) (Sc) (Sc) (Me)

JA LI MB ML ME MD MG MS MI MU MY PG PE PL PH PC PO PY QZ QU QP QS RB RH S SA ST SK SR SH LC Z ZS SL SY TR TU UC VB VG

Jasper Limestone Marble Marl Metamorphic rock (unidentified) Microdiorite Microgranite Microsyenite Migmatite Mudstone Mylonite Pegmatite Peridotite Phonolite Phyllite Porcellanite Porphyry Pyroxenite Quartz Quartzite Quartz porphyry Quartz sandstone Red-brown hardpan Rhyolite Sand Sandstone Schist Scoria Serpentinite Shale Silcrete Silt Siltstone Slate Syenite Trachyte Tuff Unconsolidated material (unidentified) Volcanic breccia Volcanic glass

(Sc) (Sd) (Me) (Uc)

(lg) (Ig) (Ig) (Me) (Sd) (Me) (Ig) (Ig) (Ig) (Me) (Sc) (Ig) (Ig) (Ig) (Me) (Ig) (Sd) (Sc) (Ig) (Uc) (Sd) (Me) (Uc) (Ig) (Ig) (Sc) (Sd) (Uc) (Sd) (Me) (Ig) (Ig)

(Sp) (Ig)

a Parenthesised abbreviations indicate genetic types: Ig – igneous rocks; Me – metamorphic rocks; Sc – sedimentary rocks, chemical or organic; Sd – sedimentary rocks, detrital; Sp – sedimentary rocks, pyroclastic; Uc – unconsolidated material.

214

215 25

1.0

2.1

3.0

2.7

2.4

7000

3000

2000

1500

600

240

Seismic velocityb (m/s)

Igneous rocks (Harder) metamorphic rocks

(Harder) sedimentary rocks (Softer) metamorphic rocks

(Softer) sedimentary rocks (Softer) metamorphic rocks

Bedrock

Faintly weathered rock

Slightly weathered rock

Concrete Moderately weathered rock

Stabilised soil Till Evaporites (Harder) saprolite Highly weathered rock

Soil (Softer) saprolite Alluvium Colluvium Eolian sediment Beach sediment Lacustrine sediment Marine sediment Fill

Regolith

Zone

a See page 211. b Seismic velocity values given for weaker materials refer to the unsaturated state. Saturation with water may double the velocity. Data sources: CJ Braybrook (pers. comm.); FJ Taylor (pers. comm.); Dobrin 1960; Bartlett 1971; Kesel 1976; Polak and Pettifer 1976: Schmidt and Pierce 1976; Hoek and Bray 1977; Church 1981; Selby 1980, 1982.

300

S or VS Strong or very strong rock

100

M Moderately strong rock

50

Consolidated (R horizon) substrate masses: W Weak rock

VW Very weak rock

1.8

1.3

0.01

Unconsolidated substrate masses: E Earth or ‘soil’

Strength class

Bulk density (Mg/m3)

Unconfined compressive strength (MPa)

Table 36 Relative strength, density and seismic velocity of dry earth and rock masses in the regolith and bedrock zonesa

Substrate

Australian Soil and Land Survey Field Handbook

aggregate of minerals connected by strong and permanent cohesive forces.’ In this context, ‘soil’ and ‘earth’ are synonyms (Standards Association of Australia 1981). Since ‘soil’ takes its pedological meaning throughout this Handbook, these low-strength substrate materials and masses are referred to as ‘earth’. The grain size of earth material ranges from clay to gravel or larger fragments. The geological distinction between sediments and sedimentary rocks occurs at about 25 MPa. This higher value is also appropriate for the minimum strength of the ‘R (rock) horizon’ in soil profile description (page 151) that cannot be dug with hand tools. Table 36 distinguishes ‘Unconsolidated substrate masses’ from ‘Consolidated (R horizon) substrate masses’ at the 25 MPa value. The table also shows corresponding values of bulk density and seismic velocity. At suitable sites, the seismic velocity of various subsurface layers can be measured using portable equipment (Williams 1988). Seismic velocity varies directly with mass strength because of a functional relation to elastic constants. Bulk density happens to vary in the same sense for most earth and rock masses. The value of any one attribute indicates the likely values of the other two. For engineering works, the following broad generalisations can be made about the strength classes of Table 36. ‘Earth’ can be picked up and carried easily using earth-moving machines such as excavators and scrapers. When stronger materials are to be moved, the first step is to reduce their strength and density to that of ‘earth’. Such material is too weak to form roads or dams without being artificially stabilised to the status of ‘very weak rock’ by compaction or other techniques (Ingles and Metcalf 1972). ‘Very weak rock’ can be dislodged with a bulldozer blade (or hand tools, for that matter), but it is easier to move if it is first broken up by a tractor-mounted ripper (Anon. 1983). ‘Weak rock’ must be ripped before it can be removed; this can be done using tractors weighing less than 40 tonnes (gross), such as the Caterpillar D8N (Anon. 1987a) and the Komatsu D155A (Anon. 1987b). ‘Moderately strong rock’ can be ripped by the heaviest tractors, but ‘strong or very strong rock’ can be broken only with explosives.

GENETIC TYPE OF SUBSTRATE MASSES Bedrock and regolith zones The mantle of earth and rock, including weathered rocks and sediments, altered or formed by land surface processes is called the regolith. The underlying zone of rocks formed or altered by deep-seated crustal processes is the bedrock.

216

Substrate

Regolith and bedrock are regarded here as zones characterised by different processes, rather than as classes of material. The original definition of regolith by Merrill (1897) stresses the latter view and includes only unconsolidated materials. The depth of the regolith zone ranges from zero, where bedrock outcrops at the surface, to over 100 m in areas of deep weathering (Ollier 1984). In areas without much sediment, the lower boundary of the regolith is the weathering front (Mabbutt 1961) where features due to weathering first appear. Where sediments are very thick, their lower layers become isolated from land surface processes by their depth and by reduced permeability due to compaction. Here the base of the regolith, which could be called a ‘lithification front’, is where most of the sediments transform to sedimentary rocks. Sedimentary rocks are often folded and faulted but, at least in Australia’s stable environment, most unconsolidated sediments remain flat-lying. Masses within the regolith zone, in contrast with those within the bedrock zone, tend to have low density, very low strength, and little cohesion between their particles or fragments. Despite Merrill’s definition, not all materials follow this tendency. Strong and cohesive masses (e.g. ferricrete) may be characteristic of the regolith. However, some layers of sedimentary rock never become strong. Other rocks are weakened within the bedrock zone by deepseated processes. Table 36 assigns types of substrate mass to either the regolith zone or the bedrock zone.

Scheme of classification Table 37 presents a scheme of classification of soil substrate masses as they are found in soil and land surveys. The main classes represent rock masses not yet weathered, those now being weathered, those transported and deposited but not yet consolidated, and those hardened while still near the surface. Named classes in this table are defined in the following glossary, ‘Glossary of substrate mass genetic types’. Since this is a genetic classification, diagnostic attributes may be hard to specify. Associated landforms should not be used as recognition criteria for observed substrate masses. They can be used to infer the nature of substrate masses that cannot be observed. In the same way, substrate observations should not be used as recognition criteria for landforms.

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Table 37 Genetic classification of substrate masses 1

2

3

4

Unweathered rocks of the bedrock zone Igneous rocks IG Plutonic rocks PL Volcanic rocks VO Metamorphic rocks ME Sedimentary rocks SR Detrital sedimentary rocks (including eolianite) SD Pyroclastic rocks (including ignimbrite) SP Chemical and organic sedimentary rocks SC Weathered rocks Partially weathered rock PW Saprolite SA Decomposed rock DR Sediments (unconsolidated) Alluvium AL Colluvium CO Scree SE Landslide deposit LD Mudflow deposit MD Creep deposit CD Sheet flow deposit SH Eolian sediment ED Eolian sand ES Loess LO Parna PA Gypsum GY Volcanic ash VA Beach sediment BE Lacustrine sediment LA Marine sediment MA Till TI Fill FI Masses hardened in the regolith s #HEMICALLYHARDENEDMATERIALS Red-brown hardpan RB Ferricrete FC Alcrete (bauxite) AC Silcrete LC Porcellanite PC Calcrete KC s %VAPORITES Halite (rock salt) HA Gypsum GY Other evaporites EV s !RTIFICIALLYHARDENEDMATERIALS Stabilised soil SO Concrete CN Other artificially hardened materials AT

218

Substrate

GLOSSARY OF SUBSTRATE MASS GENETIC TYPES Aeolianite

see Eolianite.

AC

Alcrete (bauxite)

indurated material rich in aluminium hydroxides. Commonly consists of cemented pisoliths and usually known as bauxite.

AL

Alluvium

sediment mass deposited from transport by channelled stream flow or overbank stream flow.

BE

Beach sediment

sediment mass deposited from transport by waves or tides at the shore of a sea or lake.

KC

Calcrete

any cemented, terrestrial carbonate accumulation that may vary significantly in morphology and degree of cementation. Also known as carbonate pan, calcareous pan, caliche, kunkar, secondary limestone, travertine. All show slight to strong effervescence with 1 Molar HCl.

SC

Chemical and sedimentary rocks in which mineral grains or organic fragments are not important constituents. The sedimentary rocks group includes coal, chert and non-fragmental limestones as well as saline rocks (evaporites) such as halite (rock salt) and gypsum. Chemical and organic sedimentary rocks are common in the regolith zone.

CO

Colluvium

sediment mass deposited from transport down a slope by gravity (scree), landslide (landslide deposit), mudflow (mudflow deposit), creep (creep deposit) or sheet flow (sheet flow deposit), but not by stream flow. Compared with alluvium, colluvium lacks bedding structure; is more variable in grain size (i.e. more poorly sorted); contains much local material; and is generally much more angular. Coarse particles may have particular alignments.

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CN

Concrete

artificial conglomerate rock mass of selected size grade material that has been hardened using Portland cement or other kinds of cement. Concrete is a weak rock (about 35 MPa unconfined compressive strength) usually reinforced with steel to increase its tensile strength.

CD

Creep deposit

colluvium slowly displaced a short distance downslope as a result of small irregular movements, with the net movement increasing towards the land surface.

DR

Decomposed rock weathered material (typically soft and clay-rich) produced by thorough decomposition of rock masses due to exposure to land surface processes, but with no transport. It generally lacks any structures that may have been present in the unweathered rock (see also Saprolite and Partially weathered rock).

SD

Detrital sedimentary rocks composed of mineral grains or sedimentary rocks fragments derived from pre-existing rocks. Types are distinguished in Table 34.

ET

Eolianite

consolidated sedimentary rock consisting of clastic material deposited by the wind (Bates and Jackson 1987). Includes bioclastic calcarenites.

ES

Eolian sand

eolian sediment of sand size, often taking the form of dunes, with characteristic bedding structures.

ED

Eolian sediment

sediment mass deposited from transport by the wind.

EV

Evaporite

weak sedimentary rock or sediment formed by the precipitation of solutes from water bodies on the land surface, typically as lacustrine sediments. Includes halite and gypsum.

220

Substrate

FC

Ferricrete

indurated material rich in hydrated oxides of iron (usually goethite and hematite) occurring as cemented nodules and/or concretions, or as massive sheets. This material has been commonly referred to in local usage around Australia as laterite, duricrust or ironstone.

FI

Fill

mass of artificial sediment formed by earthmoving works. Fill is sometimes compacted to the status of a very weak rock mass (stabilised soil), but typically remains an earth mass (Table 36). Garbage forms a very low-density, low-strength fill.

GY

Gypsum

evaporite consisting of hydrated calcium sulfate. Non-hydrated calcium sulfate forms closely related masses called anhydrite. It may subsequently be transported by wind as fine crystals and form lunettes or more widespread sedimentary layers blanketing the landscape.

HA

Halite (rock salt)

evaporite consisting of sodium chloride.

IG

Igneous rocks

strong or very strong rock masses formed by solidification of molten rock matter (magma) derived from below the Earth’s surface. The rocks are mainly composed of interlocking crystals. Types are distinguished in Table 34. Plutonic rocks and volcanic rocks are included.

IN

Ignimbrite

very weak to strong volcanic rock mass deposited from a flow of ash, the stronger forms being welded together by residual heat during deposition.

LA

Lacustrine sediment

sediment mass deposited from transport by waves and from sediment solution and suspension in still water in a closed depression on land.

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LD

Landslide deposit

colluvium rapidly displaced many metres downslope by failure of a mass of earth or rock. If the mass is not already a part of the regolith, the landslide incorporates it in the regolith. Original rock structures are fragmented and disorganised by the action of the landslide.

LO

Loess

eolian sediment of silt size.

MA

Marine sediment

sediment mass deposited from transport by waves and from solution and suspension in sea water.

ME

Metamorphic rocks moderately strong to very strong rock masses formed by the chemical and physical alterations of igneous or sedimentary rocks under high temperatures and/or very high pressures within the Earth’s crust. Types are distinguished in Table 34.

MD

Mudflow deposit

colluvium mixed with water to form dense fluid, and rapidly displaced metres or kilometres downslope. The material is more thoroughly disaggregated than that of a landslide deposit and lacks the bedding and sorting of grain sizes seen in alluvium.

PA

Parna

fine-grained calcareous eolian sediment consisting of 30–70% clay.

PW

Partially weathered rock

weathered material produced by exposure of rock masses to land surface processes but with no transport. Partial decomposition results in changes in colour, texture, composition, strength or form of the parent rock mass (see also Decomposed rock and Saprolite).

PL

Plutonic rocks

igneous rocks solidified at depth within the Earth’s crust.

222

Substrate

PC

Porcellanite

dense argillaceous rock of varying degree of silicification with a conchoidal fracture and general appearance of unglazed porcelain.

SP

Pyroclastic rocks

sedimentary rocks resulting from the deposition of airborne materials produced by volcanic eruptions.

RB

Red-brown hardpan

an informal name used for a particular indurated earthy material (see ‘Pans’, page 193). Often it is not known if the red-brown hardpan is a paleosol or a cemented sediment (see Wright 1983).

SA

Saprolite

a particular form of decomposed rock. It is characterised by the preservation of structures (including ‘texture’ in the petrological sense) that were present in the unweathered rock.

SE

Scree

colluvium deposited after falling or rolling from cliffed or steep slopes, consisting of loose rock fragments of gravel size or larger and generally lacking a fine interstitial component.

SR

Sedimentary rocks weak or moderately strong rock masses formed by the hardening of sediments due to compaction, recrystallisation or cementation. These processes can occur within the regolith but are promoted by burial within the Earth’s crust. Major categories of sedimentary rocks are detrital sedimentary rocks, pyroclastic rocks, and chemical and organic sedimentary rocks.

SH

Sheet flow deposit colluvium deposited from transport by a very shallow flow of water as a sheet, or network of rills on the land surface. Sheet flow deposits are very thin except at the foot of a slope and beneath sheet-flood fans.

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LC

Silcrete

strongly indurated siliceous material cemented by, and largely composed of, forms of silica, including quartz, chalcedony, opal and chert.

ST

Stabilised soil

artificial mass with the strength grade of very weak rock. It results from the ‘stabilisation’ of an earth mass by a variety of processes: compaction; the admixture of lime, Portland cement, bitumen or other substances; heating; freezing; or electrohardening. Cement stabilisation can produce a mass as strong as 10 MPa unconfined compressive strength (Ingles and Metcalf 1972).

TI

Till

sediment mass deposited from transport in ice, as in a glacier. Till is neither bedded nor sorted; it has a matrix of clay or silt enclosing larger particles of unweathered rock ranging up to large boulders.

VA

Volcanic ash

eolian sediment consisting of relatively fine (<2 mm) pyroclastic material. It often contains a proportion of highly weatherable glass.

VO

Volcanic rocks

igneous rocks solidified after eruption on to the land surface.

224

A PPE N DI X 1: SOI L TA XONOM IC U N I T S R.F. Isbell and R.C. McDonald

This appendix gives coding of soil taxonomic units in soil classification schemes most likely to be used in Australian soil and land surveys. Classification schemes appropriate to the particular survey purpose will be chosen by each survey organisation or individual.

THE AUSTRALIAN SOIL CLASSIFICATION The Australian Soil Classification (Isbell 1996) is recommended for use in Australian soil and land surveys. A complete class list and codes are given in this publication. Concepts and rationale of the Australian soil classification (Isbell et al. 1997) is designed to be read in conjunction with the classification and gives the rationale for the establishment of various classes and diagnostic criteria. Codes for the 14 Orders are listed below. Anthroposols

AN

Calcarosols Chromosols Dermosols Ferrosols Hydrosols Kandosols

CA

Kurosols Organosols Podosols Rudosols Tenosols Sodosols Vertosols

CH DE FE HY KA

225

KU OR PO RU TE SO VE

Australian Soil and Land Survey Field Handbook

If the Order is indeterminable from the available information, the code should be YY.

SOIL TAXONOMY Codes for the 11 orders of Soil Taxonomy (Soil Survey Staff 1996) are listed below. Alfisols

A

Inceptisols

I

Andisols Aridisols Entisols Histosols

C

Mollisols Oxisols Spodosols Ultisols Vertisols

M

D E H

O S U V

WORLD REFERENCE BASE FOR SOIL RESOURCES (WRB) This classification system (IUSS Working Group WRB 2006) is the framework for international classification, correlation and communication. The WRB does not replace national soil classification systems and is a tool for correlation between national systems. Codes for the 32 reference soil groups of the WRB are listed below. Acrisols Albeluvisols Alisols Andosols Anthrosols Arenosols Calcisols Cambisols Chernozems Cryosols Durisols

AC

Kastanozems Leptosols Lixisols Luvisols Nitisols Phaeozems Planosols Plinthosols Podzols Regosols Solonchaks

AB AL AN AT AR CL CM CH CR DU

226

KS LP LX LV NT PH PL PT PZ RG SC

Appendix 1

Ferralsols Fluvisols Gleysols Gypsisols Histosols

FR

Solonetz Stagnosols Technosols Umbrisols Vertisols

FL GL GY HS

227

SN ST TE UM VR

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Northcote KH, Hubble GD, Isbell RF, Thompson CH, Bettenay E (1975) ‘A description of Australian soils.’ (CSIRO Aust.: Melbourne). Ollier C (1984) ‘Weathering (2nd edn).’ (Oliver and Boyd: Edinburgh). Olson GW (1973) ‘Soil survey interpretation for engineering purposes.’ FAO Soils Bull. No. 19. Oyama M, Takehara H (1970) ‘Revised standard soil color charts.’ (Frank McCarthy Color, 38 Marshall Ave, Kew, Victoria, Australia). Parkes D, Newell G, Cheal D (2003) Assessing the quality of native vegetation: the ‘habitat hectares’ approach. Ecological Management and Restoration 4, s29–s38. Parkes D, Newell G, Cheal D (2004) The development and raison d’etre of ‘habitat hectares’: a response to McCarthy et al. Ecological Management and Restoration 5, 28–29. Payne AL, Van Vreeswyk AME, Pringle HJR, Leighton KA, Hennig P (1998) ‘An inventory and condition survey of the Sandstone–Yalgoo–Paynes Find area, Western Australia.’ Technical Bulletin no. 90, Agriculture Western Australia, South Perth. PCA (1962) ‘PCA soil primer.’ (Portland Cement Association, Old Orchard Road, Skokie, Illinois, USA). Penridge LK, Walker J (1988) The crown-gap ratio (C) and crown cover: derivation and simulation study. Australian Journal of Ecology 13, 109–120. Pettijohn FJ (1957) ‘Sedimentary rocks (2nd edn).’ (Harper: New York). Piteau DR (1971) Geological factors significant to the stability of slopes cut in rock. In ‘Planning open pit mines.’ (Ed. PWJ van Rensburg) (AA Balkema: Amsterdam). Polak EJ, Pettifer GR (1976) ‘The use of surface geophysical methods in underground water investigations.’ Bur. Min. Res. Geol. Geophys. Australia, Record 1976/108. Raunkiaer C (1934) ‘The life forms of plants and statistical plant geography.’ (Oxford University Press: Oxford). Raupach M, Tucker BM (1959) The field determination of soil reaction. Journal of the Australian Institute of Agricultural Science 25, 129–133. Reid JB, Hill RS, Brown MJ, Hovenden MJ (1999) (Eds) ‘Vegetation of Tasmania.’ Flora of Australia Supplementary Series Number 8, University of Tasmania, Forestry Tasmania, CRC for Sustainable Production Forestry, Hobart. Schmidt PW, Pierce KL (1976) Mapping of mountain soils west of Denver, Colorado, for landuse planning. In ‘Geomorphology and engineering.’

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(Ed. DR Coates) (Dowden, Hutchinson and Ross: Stroudsburg, Pennsylvania) pp. 43–54. Selby MJ (1980) A rock mass strength classification for geomorphic purposes: with tests from Antarctica and New Zealand. Zeitschrift für Geomorphologie 24, 31–51. Selby MJ (1982) ‘Hillslope materials and processes.’ (Oxford University Press: Oxford). Smith GD, Arya LM, Stark J (1975) The densipan, a diagnostic horizon of densiaquults for soil taxonomy. Soil Science Society of America Proceedings 39, 369–370. Smyth A, James C, Whiteman G (2003) (Eds) ‘Expert technical workshop: biodiversity monitoring in the Rangelands: a way forward.’ Report to Environment Australia, vol. 1, Centre for Arid Zone Research, CSIRO Sustainable Ecosystems, Alice Springs. Soil Survey Staff (1951) ‘Soil survey manual.’ USDA Agricultural Handbook No. 18 (Government Printer: Washington, DC). Soil Survey Staff (1975) ‘Soil Taxonomy: a basic system of soil classification for making and interpreting soil surveys.’ USDA Agricultural Handbook No. 436 (Government Printer: Washington, DC). Soil Survey Staff (1990) ‘Keys to Soil Taxonomy (4th edn).’ SMSS Technical Monograph No. 6 (Virginia Polytechnic and State University: Blacksburg, Virginia). Soil Survey Staff (1996) ‘Keys to Soil Taxonomy (7th edn).’ (Pocahontas Press: Blacksburg, Virginia). Specht RL, Roe EM, Boughton VH (1974) (Eds) Conservation of major plant communities in Australia and Papua New Guinea. Australian Journal of Botany Supplement No. 7. Speight JG (1967) Appendix 1: explanation of land system descriptions. In ‘Lands of Bougainville and Buka Islands, Territory of Papua and New Guinea.’ (RM Scott, PB Heyligers, JR McAlpine, JC Saunders, and JG Speight.) CSIRO Aust. Land Res. Ser. No. 20, 174–184. Speight JG (1971) Log–normality of slope distributions. Zeitschrift für Geomorphologie 15, 290–311. Speight JG (1974) ‘A parametric approach to landform regions.’ Inst. Brit. Geography Special Publication No. 7, 213–230. Speight JG (1976) Numerical classification of landform elements from air photo data. Zeitschrift für Geomorphologie Suppl. 25, 154–168.

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Speight JG (1977) Landform pattern descriptions from aerial photographs. Photogrammetria 32, 161–182. Speight JG (1980) The role of topography in controlling through-flow generation: a discussion. Earth Surface Processes and Landforms 5, 187–191. Stace HCT, Hubble GD, Brewer R, Northcote KH, Sleeman JR, Mulcahy MJ, Hallsworth EG (1968) ‘A handbook of Australian soils.’ (Rellim Tech. Pubs: Glenside, SA). Standards Association of Australia (1977) ‘Australian standard 1289: methods of testing soils for engineering purposes.’ (Standards Association of Australia, Standards House, 80 Arthur Street, North Sydney, NSW). Standards Association of Australia (1981) ‘Site investigations, known as the SAA Site Investigation Code, AS 1726–1981.’ (Standards Association of Australia, Standards House, 80 Arthur Street, North Sydney, NSW). Talsma T (1983) Soils of the Cotter catchment area, ACT: distribution, chemical and physical properties. Australian Journal of Soil Research 21, 241–255. Terzaghi K, Peck RB (1967) ‘Soil mechanics in engineering practice (2nd edn).’ (Wiley: New York). Thackway R, Lesslie R (2005) Vegetation assets, states and transitions (VAST): accounting for vegetation condition in the Australian landscape. BRS Technical Report, Bureau of Rural Sciences, Canberra, [confirmed 9 March 2008]. Thackway R, Lesslie R (2006) Reporting vegetation condition using the Vegetation Assets, States, and Transitions (VAST) framework. Ecological Management and Restoration 7(s1), s53–s62. Thackway R, Neldner VJ, Bolton MP (2008) Vegetation. In ‘Guidelines for surveying soil and land resources (2nd edn).’ (Eds NJ McKenzie, MJ Grundy, R Webster and AJ Ringrose-Voase) (CSIRO Publishing: Melbourne). Thackway R, Sonntag S, Keenan R (2006) ‘Measuring ecosystem health and natural resource productivity: vegetation condition as an indicator of sustainable, productive ecosystems.’ (Science for Decision Makers, Bureau of Rural Sciences: Canberra, ACT). US Army Corps of Engineers (1953) ‘Unified soil classification system.’ US Army Corps of Engineers Waterways Experiment Station, Technical Manual 3–357, Vicksburg, Mississippi, USA. Walker J, Crapper PF, Penridge LK (1988) The crown-gap ratio (C) and crown cover: the field study. Australian Journal of Ecology 13, 101–108.

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239

INDEX

Where more than one page reference is given, the numbers in bold type indicate reference to definitions or principal discussion. accordance, surfaces of 45 aggradation 29, 138 sampling area for 5 site dimension for 5 air photo reference 10–1 alcove 32 alcrete (bauxite) 194, 219 algae fresh or brackish 88 marine 88 alluvial fan 58 alluvial plain 59 alluvium 219 altan units 19 alteration of substrate material 211 anastomotic plain 59, 61 angular blocky structure 173, 176 anti-gradational activity 29 apedal 171–2 aquatic higher plants 88 artificial levee 40 aspect 127 sampling area for 5 site dimensions for 5 attributes 1, 2 of landform elements 17–8 of landform pattern 44–5 soil and site 3 Australian Map Grid 8 backplain 32 badlands 61 bank 32

bar 32 bar plain 61 barchan dune 32 bare surface 88 bauxite (alcrete) 194, 219 beach 32 beach ridge 33 beach ridge plain 61 beach sediment 219 bed, see stream bed bedrock 216 bench 33 berm 33 bidirectional channel network 52 bleach conspicuous 152 sporadic 152 bleached A2 horizon 152 blow-out 33 bolus 164 boulders 140 boundary between horizons 199–200 breakaway 33 broad floristic formation 75, 95–102 broad floristic subformation 75, 77 bryophyte 89 buried soils 153, 156 calcrete 192–3, 219 caldera 62 carbonate 154, 155, 198 cast 180 centrifugal channel network 52 centripetal channel network 52 channel, see stream channel channel bench 33

240

channel network, see stream channel chenier plain 62 chenopod shrub 89 cirque 33 clay 162 clay skins 182 cliff 33 cliffed slope 19 cliff-footslope 33, 38 clod 181 closed depression 20 coarse fragments 139–43, 170–1 abundance 139–40, 141 distribution 170–1 lithology 142 shape 142, 143 size 140 soil profile 170–1 strength 142 surface 139 coarse gravel 162 coarse gravelly 140 coarse sand 162 coarse silt 162 cobbles 140, 162 coffee rock, see organic pan coherent 172, 190 collapse doline 38 colluvium 219 colour 159 colour patterns 159–61 columnar structure 173, 175 complexity, rainforest 109–11 concrete 220 condition surface soil 189–91 vegetation 120–1, 125 cone (volcanic) 38 consistence 186–9 degree of plasticity 188–9 stickiness 187–8

Index

strength 187 type of plasticity 188 conspicuous bleach 152 contour trench 132 convergent channel network 52 coordinates 7–9 coral reef 62 core-stones 44 course lines 28 cover classes 81 cover type 80–7 cover−abundance 86–7 covered plain 62–3 cracking clays 152–3 cracks 184, 189 crater 38 creep deposit 220 crest 20 crown type 80–7 crown separation ratio 82–3 cryptogam 89 cryptogam surface 190 cultivation pan 195 cutans 182–3 cut face 38 cut-over surface 38 dam 38 date 13 datum 7–8 debil-debil 130 decomposed rock 220 deep weathering profiles 211 deflation basin 38 delta 63 densipan 153, 194 depression 20 depth of horizons 156 to free water 144 to R horizon 156, 159 detrital sedimentary rocks 220 diastrophism 31 disintegrated channel network 52 distributary channel pattern 50 disturbance of site 128

sampling area for 5 site dimensions for 5 divergent channel network 52 doline collapse 38 solution 42–3 drainage density 48 drainage depression 38 drainage height 28, 128 sampling area for 5 site dimensions for 5 drainage 202–4 dune 26, 38 see also barchan dune, hummocky dune, linear or longitudinal dune, parabolic dune dunecrest 26, 38 dunefield 63 duneslope 26, 38 duripan 193 earth 216 earth movements 31 earthy pan 155 effervescence 198 elevation 127–8 sampling area for 5 site dimensions for 5 eluvial horizon 148 embankment 38 emergents 79, 94–5, 115–6 eolianite 220 eolian sand 220 eolian sediment 220 erosion 133–8 accelerated 133–4 gully 136–7 mass movement 138 natural 133 rill 136 sampling area for 5 scald 135 sheet 135–6 site dimensions for 5 state 134 stream bank 137 tunnel 137 water 135–7 wave 137

241

wind 134–5 erosional stream channel 49 escarpment 63–4 estuary 39 evaporite 220 explicit use of attributes 1, 17, 45 extraterrestrial agents 31, 57 extremely low relief 47 fabric 181–2 fan 39 faunal accumulation 153 fern 89, 115 ferricrete 194, 221 ferruginised 211 field pH 198 field texture 161–70 determination 163–4 grade 164–6 modifiers 166–7 of organic soils 169–70 properties affecting 167–9 qualification 166–7 fill 221 fill-top 39 fine clay 162 fine gravel 162 fine gravelly 140 fine sand 162 fine silt 162 flat 20, 22, 133 flood-out 39 flood plain 64 floristics 75, 97–102 foliage cover 80, 83 classes 81 food 89 footslope 39 forb 89 foredune 39 formation 75, 80–7 fragipan 155, 193 fragment 181 gently inclined slope 19 gently undulating 46, 47 geomorphological activity anti-gradational 29 gradational 29

Australian Soil and Land Survey Field Handbook

mode 29–30 status 54–5 geomorphological agent in a landform element 30 in a landform pattern 52, 54 gilgai 129–30 components 130, 133 depression 133 mound 133 shelf 133 types 129–130 gleying 153 glossary growth forms 88–93 landform element types 31–44 landform pattern types 55–72 substrate genetic mass types 219–27 GPS 7, 10 gradational activity 29 grain size grade limits 162, 206–7 granular structure 179, 180 grass 89 cereals 90 hummock 91 other industrial 90 pasture 89 planted/cultivated 89 tussock 93 gravel 162 gravel-sized 207 grid reference 8 ground cover 82, 83 ground truth 2 growth forms standard vegetation 88– 93 rainforest vegetation 114–5 wetland vegetation 106 growth stage 120 indicators 122–3 gully 39 gully erosion 136–7 gypsum 155, 221

halite 221 hard setting 190 heath 90 height classes, vegetation 93–5 herb, planted/cultivated 90 annual, food 90 annual, non-food 90 perennial, food 90 perennial, non-food 90 high relief 47 hillcrest 39 hillock 20 hills 64 hillslope 39 horizon boundary distinctness 199 shape 200 horizons 148–56 A 149–50 B 150–1 bleached 152, 154 boundaries 199–200 buried 153, 156 C 151 D 151 depth 156 E 148 eluvial 148 in cracking clays 152–3 O 148 P 149 R 151, 216 subdivision 155 suffixes 153–5 transitional 151–2 horizontal interval 133 hummock 133 hummock grass 91 hummocky dune 40 hummocky microrelief 130–1 hydraulic conductivity (Ks) 200 igneous rocks 213, 221 ignimbrite 221 incipient stream channel 49 incoherent 171, 190

242

integrated channel network 52 internal drainage 202 interrupted channel network 52 intertidal flat, see tidal flat inundation 138–9 sampling area for 5 site dimension for 5 ironpan 194 kaolinised 211 karst 65 kwongan shrub 90 lacustrine plain 65 lacustrine sediment 221 lagoon 40 lake 40 land facet 16 landform 15–72 landform description 15–7 landform element description 17–31 dimensions 16, 17, 27 genesis 28–9 morphological type 19–26 relative inclination 21–2 sampling area for 5 short description 26–7 site dimensions for 5 toposequence position 28 types 31–44 landform pattern boundaries 45 characteristic dimension 16, 17 description 44–55 glossary of types 55–72 sampling area 5 short description 46 site dimension 5 landslide 40 landslide deposit 222 land surface 15, 127–45 sampling area 5 site dimensions for 5 land system 16 land unit 16 large scale surveys 2

Index

laterite profiles 211 latitude 9 lava plain 65–6 leaf size 111–3 lenticular structure 178, 180 levee 40 level slope class 19 lichen 91 life form 80 linear dune 40 lithification front 217 lithologic discontinuities 156, 157 lithological type of substrate material 209–10, 212–3 location 7–11 loess 222 longitude 9 longitudinal dune 40 longitudinal dunefield 66 lower slope 20, 21 lower stratum 94 low hills 66 low relief 47 low terraces, see channel bench lunette 40 maar 40 macrophyll 112, 113 macropores 184–185 made land 66–7 mallee (tree or shrub) 91 mangans 182 manganiferous pan 194 map scale 9 sheet number 9–10 topographic sheets 9–10 mapping units minimum width 17 marine plain 67 marine sediment 222 mass movement 138 massive 172 meander plain 67 medium sand 162 mesophyll 112, 113 metamorphic rocks 213, 222 meteor crater 67

microphyll 112, 113 microrelief 129–33 biotic 131 component sampled 133 contour trench 132 gilgai 129–30 horizontal interval 133 hummocky 130–1 karst 132 other 132 sampling area for 5 site dimensions for 5 vertical interval 133 mid-slope 20, 21 mid-stratum 79, 84 mineral composition of substrate material 208 modal slope 45–6, 47 mode of geomorpho-logical activity 29–30, 52 moderately inclined slope 19 montane rainforest (Tasmanian) 119 morphological type of landform element 19–26 moss 114 mottles 159–61 abundance 160 colour 161 contrast 160 distinctness of boundaries 161 size 160 mound 41 mountains 67–8 mudflow deposit 222 myrtle beech rainforest (Tasmanian) 119 nanophyll 112, 113 National Vegetation Information System (NVIS) 15, 74, 75 non-directional channel network 52 non-tributary channel pattern 50 non-woody plant 75, 80 notophyll 112, 113

243

open depression 20 organic pan 194 organic soils 169–70 ortstein 194 ox-bow 41 pallid zone 211 palm fan 115 feather 115 pans 192–5 cementation 192 continuity 195 structure 195 type 192–5 parabolic dune 41 parabolic dunefield 68 parna 222 partially weathered rock 222 peat 169–70 pebbles 140 peds primary 180 size 172–3, 174–9 pedality compound 180 grade 171–2 type 173–80 pediment 41, 68 pediplain 69 pedologic discontinuities 155 pedologic organisation 150 pedon 147 peneplain 69 permeability 200–2 pH 198 phi scale 162 pit 41 plain 41, 69 planar escarpment 63 plant non-woody 75, 80 woody 75, 80, 93 plasticity degree 188–9 type 188 plateau 69 platy structure 173, 174 playa 41 playa plain 69–70

Australian Soil and Land Survey Field Handbook

plutonic rocks 222 poached 191 polyhedral structure 173, 177 porcellanite 223 pores 184–5 porosity of substrate material 208 precipitous slope 19 prior stream 41 prismatic structure 173, 175 projection 8 projective foliage cover 80, 81 pyroclastic rocks 223 rainfall 13 rainforest 91, 109–20 complexity 109–11 crown cover and height 115 emergents 115–6 examples 118 indicator growth forms 114–5 leaf size 111–3 sclerophylls in 116 species 113–4 Tasmanian 116, 119–20 tropical/subtropical 109– 16, 117–8 rainforest tree, see tree, rainforest red-brown hardpan 193, 223 reef flat 42 regolith 216 relict landform 54 relief 45 class 47, 48 estimation 45 residual rise 42 restricted soil bodies 5 sampling area for 5 reticulated channel pattern 50 ridge 20, 26 ridge lines 27 rill erosion 136 risecrest 42 rises 70 riseslope 42

riverine landform patterns 58, 59 rock 216 rock flat 42 rockland 144 rock outcrop 143–4 sampling area for 5 site dimensions for 5 rock platform 42 rock type classification 212–4 rolling 46, 47 roots 199 runoff 144–5 sampling area for 5 site dimensions for 5 runon 138–9 rush 91 saline 191 samphire shrub 91 sampling area for aggradation 5, 134 aspect 5 depth to free water 5 disturbance 5 drainage height 5 elevation 5 erosion 5, 134 inundation 5, 134 land surface 5 landform element 5, 16 landform pattern 5, 16 microrelief 5 rock outcrop 5 runoff 5 slope 5 surface coarse fragments 5 vegetation 86, 87 sand 162 sand plain 70 sand-sized 207 saprolite 223 scald 42 scald erosion 135 scale map 9 mapping 16, 17 scarp 42

244

scarp-footslope 42 sclerophyll 116 scoria 210 scree 223 scroll 42 scroll plain 42 seagrass, marine 91 sedge 92 sedimentary rocks 212, 223 chemical and organic 219 detrital 220 segregations of pedogenic origin 195–8 abundance 196 form 196–7 magnetic attributes 198 nature 196 size 197 strength 197–8 seismic velocity 215 self-mulching 189 sheet erosion 135–6 sheet-flood fan 70 sheet flow deposit 223 shelf 133 shrub 92 chenopod 89 food 92 heath 90 kwongan 90 mallee 91 non-food 92 samphire 91 SI units 3 sieve apertures 162 silcrete 224 silicification 211 silt 162 silt-sized 207 simple slope 20, 21 single grain 171 sinkhole 132 site attributes, importance of 2 concept 5 dimensions 5 disturbance 128 site dimensions for aggradation 5, 134

Index

aspect 5 depth to free water 5 disturbance 5 drainage height 5 elevation 5 erosion 5, 134 inundation 5, 134 land surface 5 landform element 5, 16 landform pattern 5, 16 microrelief 5 rock outcrop 5 runoff 5 slope 5 surface coarse fragments 5 vegetation 86, 87 size fractions 162 slickensides 183 slope 21 as a landform element attribute 17 as a type of landform element 18–9 categories 21 class boundaries 19 evaluation 18 inclination 21–2 modal, as a landform pattern attribute 45–6 sampling area for 5 site dimensions for 5 value 18 slope lines 20, 24, 27 soil classes 3 classification 3, 225–7 engineering definition 215 horizons see Horizons parent material 151, 205 properties 2 soil observation 147–8 soil profile 147–204 coarse fragments in 170–1 described by 13 soil structure 171–81 grade 171–2 size 172–3, 174–9 type 173, 180

soil surveys 1 soil taxonomic units 225–7 Australian Soil Classification 225–6 Soil Taxonomy 226 World Reference Base 226–7 soil texture 161–70 soil water regime 200–4 soil water status 186 solum 151 solution doline 42–3 species codes 96–7 sporadic bleach 152 spring hollow 132 mound 132 stabilised soil 224 stagnant alluvial plain 70–1 State or Territory 7 steep slope 19 sticky point 163, 188 stones 140 strata, vegetation 77–80 stream bank 32 stream bank erosion 137 stream bar 32 stream bed 43 stream channel 43 depth relative to width 49–50 development 49 frequency 48 migration 50 network directionality 51, 52 network integration 50–2 occurrence 46, 48–52, 53 pattern 51 spacing 48 stream-wise channel pattern 50, 51 strength of substrate materials 209 stress cutans 183 structural formation 75, 88–95 structure soil, see soil structure

245

subangular blocky structure 173, 176 subplastic 188 substrate 205–24 substrate masses 205 alteration 211 bulk density 215 genetic type 216–24 mass strength 211, 216 properties 210–6 spacing of discontinuities 210 substrate material 205 grain size 206–7 confidence, parent material 206 lithological type 209 mineral composition 208 point of observation 205– 6 porosity 208 properties 206–10 strength 209 structure 207–8 texture 207 type of observation 205–6 unconsolidated material 210, 214 summit surface 43 superplastic 188 supratidal flat 43 surface coarse fragments 139–43 sampling area for 5 site dimensions for 5 surface crust 190 surface flake 190 surface soil condition 189–91 surveys detailed 3 reconnaissance 3 scale of 2 swale 43 swamp 43 swamp hummock 131 tallest stratum 79, 94 talus 43 Tasmanian rainforest 116, 119–20

Australian Soil and Land Survey Field Handbook

terrace (alluvial) 71 terrace flat 43 terrace plain 44 terraced land (alluvial) 71 terracettes 132 texture diagram 163 field 161–70 laboratory 161 thin ironpan 194 tidal creek 44 tidal flat 44, 71 till 224 topographic map sheets 9–10 toposequence 21 tor 44 trampled 191 tree 92 food 93 landscaping 93 mallee 91 non-food 93 rainforest 92 trench 44 contour 132 tributary channel pattern 50 tropical/subtropical rainforest 109–16, 117–8 tumulus 44 tunnel erosion 137

tussock grass 93 type of soil observation 147– 8 unconsolidated substrate materials 210, 214 undulating 47 unidirectional channel network 52 units, SI specified 3 upper slope 20, 21 vale 20 valley flat 44 vegetation 73–125 broad floristic formation 75, 95–102 condition 120–1, 125 cover classes 81 crown types 85 emergents 79, 94–5, 115–6 examples of coding 102– 5, 118, 119–20 floristics 97–102 formation 75, 80–7 growth form 88–95, 106 growth stage 120, 122–4 height 93–4, 95 rainforest 109–20 recognising strata 77–80

246

site dimension 86, 87 standard classification 74, 77, 102, 109 structural formation 88– 95 wetlands 103–9 vertical interval 133 very coarse sand 162 very fine sand 162 very gently inclined slope 19 very high relief 47 very low relief 47 very steep slope 19 vine 93, 115 voids 184 volcanic ash 224 volcanic rocks 224 volcano 72 wallum shrub 90 water erosion 135–7 water repellence 191–2 wave erosion 137 weathering front 217 wetlands 103–9 growth forms 106 types 106–9 wind erosion 134–5 woody plant 75, 80, 93