Existing Vegetation Classification and Mapping Technical Guide Version 1.0

United States

Department of

Agriculture

Forest Service

Ecosystem Management 

Coordination Staff

Gen. Tech. Report WO-67

April 2005

Existing Vegetation

Classification and

Mapping Technical Guide 

Version 1.0
United States

Department of

Agriculture

Forest Service

Ecosystem Management 

Coordination Staff

Gen. Tech. Report WO-67

April 2005

Existing Vegetation

Classification and

Mapping Technical Guide 

Version 1.0

Ronald J. Brohman and Larry D. Bryant

Technical Editors and Coordinators

Authored by:

Section 1: Existing Vegetation Classification and Mapping Framework

David Tart, Clinton K. Williams, C. Kenneth Brewer, Jeff P. DiBenedetto, and 

Brian Schwind

Section 2: Existing Vegetation Classification Protocol 

David Tart, Clinton K. Williams, Jeff P. DiBenedetto, Elizabeth Crowe,

Michele M. Girard, Hazel Gordon, Kathy Sleavin, Mary E. Manning, 

John Haglund, Bruce Short, and David L. Wheeler

Section 3: Existing Vegetation Mapping Protocol 

C. Kenneth Brewer, Brian Schwind, Ralph J. Warbington, William Clerke, 

Patricia C. Krosse, Lowell H. Suring, and Michael Schanta 
Team Members

Technical Editors

Ronald J. Brohman National Resource Information Requirements Coordinator, Washington Office

Larry D. Bryant Assistant Director, Forest and Range Management Staff, Washington Office

Authors

David Tart Regional Vegetation Ecologist, Intermountain Region, Ogden, UT

C. Kenneth Brewer Landscape Ecologist/Remote Sensing Specialist, Northern Region, Missoula, MT

Brian Schwind Remote Sensing Specialist, Pacific Southwest Region, Sacramento, CA

Clinton K. Williams Plant Ecologist, Intermountain Region, Ogden, UT

Ralph J. Warbington Remote Sensing Lab Manager, Pacific Southwest Region, Sacramento, CA

Jeff P. DiBenedetto Ecologist, Custer National Forest, Billings, MT

Elizabeth Crowe Riparian/Wetland Ecologist, Deschutes National Forest, Bend, OR

William Clerke Remote Sensing Program Manager, Southern Region, Atlanta GA

Michele M. Girard Forest Hydrologist/Ecologist, Prescott National Forest, Camp Verde, AZ

Hazel Gordon Vegetation Ecologist, Pacific Southwest Region, Sacramento, CA

Kathy Sleavin Technical Support Group Leader, Natural Resource Information System (NRIS) FieldSampled Vegetation (FSVeg), Fort Collins, CO

Patricia C. Krosse Ecology & Botany Program Manager, Tongass National Forest, Ketchikan, AK

Mary E. Manning Regional Vegetation Ecologist, Northern Region, Missoula, MT

Lowell H. Suring Wildlife Ecologist, Rocky Mountain Research Station, Boise ID

Michael Schanta Resource Information Manager, Mark Twain National Forest, Rollins, MO

John Haglund Ecologist, NRIS Terra, Sandy, OR

Bruce Short Timber Sales/Silviculture Program Leader, Rocky Mountain Region, Lakewood, CO

David L. Wheeler Rangeland Vegetation Group Leader, Rocky Mountain Region, Lakewood, CO

Editor

Judy Tripp Geospatial Services Group, Engineering, Northern Region, Missoula, MT

This document should be cited as follows:

Brohman, R.; Bryant, L. eds. 2005. Existing Vegetation Classification and Mapping Technical Guide. Gen. Tech. Rep.

WO–67. Washington, DC: U.S. Department of Agriculture Forest Service, Ecosystem Management Coordination Staff.

305 p.

Sections 1 through 3 should be cited individually as follows:

Tart, D.; Williams, C.; Brewer, C.; DiBenedetto, J.; and Schwind, B. 2005. Section 1: Existing Vegetation Classification

and Mapping Framework. In: Brohman, R; Bryant, L. eds. Existing Vegetation Classification and Mapping Technical

Guide. Gen. Tech. Rep. WO–67. Washington, DC: U.S. Department of Agriculture Forest Service, Ecosystem

Management Coordination Staff.
Tart, D.; Williams, C.; DiBenedetto, J.; Crowe, E.; Girard, M.; Gordon, H.; Sleavin, K.; Manning, M.; Haglund, J.;

Short, B.; and Wheeler, D. 2005. Section 2: Existing Vegetation Classification Protocol. In: Brohman, R; Bryant, L.

eds. Existing Vegetation Classification and Mapping Technical Guide. Gen. Tech. Rep. WO–67. Washington, DC: U.S.

Department of Agriculture Forest Service, Ecosystem Management Coordination Staff.

Brewer, C.; Schwind, B.; Warbington, R.; Clerke, W.; Krosse, P.; Suring, L.; and Schanta, M. 2005. Section 3: Existing

Vegetation Mapping Protocol. In: Brohman; R. Bryant, L. eds. Existing Vegetation Classification and Mapping

Technical Guide. Gen. Tech. Rep. WO–67. Washington, DC: U.S. Department of Agriculture Forest Service,

Ecosystem Management Coordination Staff.

The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of

race, color, national origin, gender, religion, age, disability, political beliefs, sexual orientation, and marital or family

status. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for

communication of program information (e.g., Braille, large print, audiotape) should contact USDA’s TARGET Center

at 202–720–2600 (voice and TDD).

To file a complaint of discrimination, write USDA, Director, Office of Civil Rights, Room 326W, Whitten Building,

14th and Independence Avenue, SW, Washington, DC 20250–9410 or call 202–720–5964 (voice or TDD).
iv Existing Vegetation Classification & Mapping Technical Guide
Existing Vegetation Classification & Mapping Technical Guide v

Acknowledgments

The following individuals provided information, advice, and/or assistance that contributed to the completion of this document:

Robert Pfister Professor Emeritus, University of Montana, Missoula, MT

Alison Hill Assistant Director, U.S. Department of Agriculture 

(USDA) Forest Service, Rocky Mountain Research

Station, Fort Collins, CO

Patrice Janiga Assistant Director, USDA Forest Service, Design and 

Quality Assurance, IMI, Fort Collins, CO

David Meriwether Ecosystem Management Coordinator, USDA Forest 

Service, Southern Region, Atlanta, GA

Douglas S. Powell National Monitoring and Evaluation Coordinator, USDA 

Forest Service, Washington Office

Betsy Banas Staff Cartographer, Geospatial Services Group, 

Washington Office

James D. Ellen Regional Inventory Specialist, USDA Forest Service, 

Alaska Region, Juneau, AK

James White Forester, USDA Forest Service, NRIS Terra, Sandy, OR

Cathy Askren Liaison Officer, USDA Forest Service, NRIS Interagency 

Regional Group (IRM), Sandy, OR

Robert L. White Forest Silviculturist, USDA Forest Service, Allegheny 

National Forest, Warren, PA

The ongoing work of the Federal Geographic Data Committee (FGDC), Vegetation

Subcommittee, and the Ecological Society of America (ESA) Vegetation Classification

Panel provided a valuable foundation for the development of this protocol. We thank the

members of each group for their willingness to communicate openly and share information.
vi Existing Vegetation Classification & Mapping Technical Guide
Existing Vegetation Classification & Mapping Technical Guide vii

Table of Contents

Section 1. Existing Vegetation Classification and Mapping Framework

1.1 Introduction .............................................................................................................1-1

1.1.1 Organization of Technical Guide .....................................................................1-1

1.1.2 Vegetation Classification Standards.................................................................1-1

1.1.3 Vegetation Mapping Standards ........................................................................1-2

1.2 Background and Objectives....................................................................................1-2

1.2.1 Existing Vegetation Information Uses .............................................................1-2

1.2.2 Relationship of Existing and Potential Natural Vegetation..............................1-4

1.2.3 Vegetation Classification Business Requirements...........................................1-4

1.2.4 Vegetation Mapping Business Requirements...................................................1-5

1.2.5 Protocol Objectives ..........................................................................................1-6

1.3 Protocol Overview....................................................................................................1-7

1.3.1 Vegetation Classification Concepts and Definitions .......................................1-7

1.3.2 Vegetation Mapping Concepts and Definitions .............................................1-10

1.4 Roles and Responsibilities.....................................................................................1-14

1.5 Relationship to Other Federal Programs and Standards ..................................1-15

1.5.1 Relationship to the FGDC National Vegetation Classification Standard ......1-16

1.5.2 Relationship to Other Forest Service Inventory and Monitoring Protocols ..1-20

1.5.3 Relationship to Other Federal Programs and Standards ................................1-24

1.5.4 Relationship to Non-Federal Programs and Standards ..................................1-24

1.6 Change Management.............................................................................................1-24

Section 2. Existing Vegetation Classification Protocol

2.1 Purpose......................................................................................................................2-1

2.2 Planning and Design ................................................................................................2-1

2.2.1 Vegetation Classification Process ....................................................................2-1

2.2.2 Classification Approaches and Concepts.........................................................2-7

2.2.3 Vegetation Classification Criteria ....................................................................2-8
viii Existing Vegetation Classification & Mapping Technical Guide

2.2.4 Association Criteria......................................................................................2-11

2.2.5 Alliance Criteria...........................................................................................2-12

2.2.6 Classification Standards ..............................................................................2-13

2.3 Sampling Strategy................................................................................................2-15

2.3.1 Stratification of Study Area .........................................................................2-15

2.3.2 Plot Location................................................................................................2-16

2.4 Sampling Methods ...............................................................................................2-17

2.4.1 Plot Size and Shape......................................................................................2-17

2.4.2 Identification of Life Forms and Layers......................................................2-19

2.4.3 Species Identification...................................................................................2-22

2.4.4 Species Canopy Cover Data.........................................................................2-22

2.4.5 Canopy Cover Estimation ............................................................................2-23

2.4.6 Plant Height and Diameter Data ..................................................................2-24

2.4.7 Environmental Attribute Data ......................................................................2-24

2.4.8 Metadata.......................................................................................................2-25

2.4.9 FGDC Physiognomic Crosswalk Attributes.................................................2-26

2.5 Data Storage .........................................................................................................2-28

2.5.1 Data Cleaning...............................................................................................2-28

2.6 Data Analysis ........................................................................................................2-29

2.7 Reporting ..............................................................................................................2-30

2.7.1 Naming Vegetation Types.............................................................................2-30

2.7.2 Vegetation Type Descriptions.......................................................................2-33

2.7.3 Vegetation Type Metadata ............................................................................2-34

Section 3. Existing Vegetation Mapping Protocol

3.1 Purpose ...................................................................................................................3-1

3.1.1 Background and Specific Objectives.............................................................3-1

3.1.2 Business Requirements ..................................................................................3-1

3.1.3 Products..........................................................................................................3-2
Existing Vegetation Classification & Mapping Technical Guide ix

3.2 Planning, Design, Development, and Assessment................................................3-3

3.2.1 Project Management ......................................................................................3-3

3.2.2 Map Standards................................................................................................3-6

3.2.3 Map Design ..................................................................................................3-18

3.2.4 Map Product Development and Assessment................................................3-25

3.3 Field and Aerial Photography Data....................................................................3-55

3.3.1 Field Data Collection Standards and Methods ............................................3-56

3.3.2 Field Data Forms..........................................................................................3-56

3.3.3 Aerial Photo Data Collection Standards and Methods ................................3-56

3.3.4 Aerial Photo Data Forms..............................................................................3-56

3.3.5 Field Reviews...............................................................................................3-56

3.4 Metadata/Documentation....................................................................................3-57

3.4.1 Metadata Entry Methods and Verification...................................................3-57

3.4.2 Database Structure Overview ......................................................................3-59

3.4.3 Data Management ........................................................................................3-59

Literature Cited............................................................................................................4-1

Glossary.........................................................................................................................5-1

List of Abbreviations and Acronyms ..........................................................................6-1

Appendices.................................................................................................................1A-1

1A. Federal Geographic Data Committee Guiding Principles for Vegetation

Classification.................................................................................................1A-1

1B. National Vegetation Classification Standards Physiognomic Hierarchy

Overview........................................................................................................1B-1

1C. Draft Key to Federal Geographic Data Committee Physiognomic 

Subclass .........................................................................................................1C-1

2A. Example Field Forms and Instructions .........................................................2A-1

3A. Example of Mapping Keys to Life Form and Dominance Types ................3A-1

3B. Example of a Structured Aerial Photointerpretation Data Gathering 

Protocol..........................................................................................................3B-1
x Existing Vegetation Classification & Mapping Technical Guide

3C. Examples of Existing Vegetation Mapping Protocols Used to Produce MidLevel Geodatasets..........................................................................................3C-1

3D. Metadata Development Questions.................................................................3D-1

3E. Standard Metadata Template ..........................................................................3E-1

3F. Existing Vegetation Database Structure..........................................................3F-1

3G. Comparison of Anderson Land Use Classes with Physiognomic Class and

Subclass .........................................................................................................3G-1

List of Figures

2.1 Flow diagram of vegetation classification process ..........................................2-2

2.2 Dichotomous key example..............................................................................2-14

3.1 Map units and attributes in a map feature example .......................................3-14

3.2 Physiognomic types ........................................................................................3-23

3.3 Dominance types ............................................................................................3-23

3.4 Tree canopy cover ...........................................................................................3-24

3.5 Combined dominance type and tree canopy cover.........................................3-24

3.6 Map product development and assessment mid-level vegetation mapping ...3-27

3.7 Map product development and assessment base-level vegetation 

mapping..........................................................................................................3-31

List of Tables

1.1 Existing vegetation map levels, business requirements, and applications .....1-12

1.2 Existing vegetation map levels and characteristics ........................................1-13

1.3 I&M framework ..............................................................................................1-20

1.4 Relationships of existing vegetation I&M activities to other Forest Service 

activities .........................................................................................................1-21

1.5 Comparison of sampling approaches for existing vegetation I&M activities.....1-22

2.1 Two approaches to hierarchical classification ..................................................2-8

2.2 Commonly used macroplot sizes....................................................................2-18

2.3 Summary of tree and shrub layers..................................................................2-21

2.4 Plot sizes and dimensions of squares equaling 1- and 5-percent of 

the plot ...........................................................................................................2-23

2.5 Required FGDC life forms .............................................................................2-26

2.6 Required FGDC life form modifiers..............................................................2-27

2.7 Synthesis table for vegetation classification example....................................2-31

2.8 Association table for vegetation classification example.................................2-32

2.9 Examples of vegetation type names ...............................................................2-33
Existing Vegetation Classification & Mapping Technical Guide xi

3.1 Existing vegetation map levels supporting Forest Service business ................3-2

3.2 Relationship between Anderson 1 and FGDC physiognomic class .................3-9

3.3A Physiognomic map attributes.........................................................................3-9

3.3B Physiognomic classes—order ........................................................................3-9

3.3C Physiognomic lasses—class.........................................................................3-10

3.3D Physiognomic classes—subclass .................................................................3-11

3.4 Floristic map attributes ...................................................................................3-11

3.5 Total tree canopy closure map units ...............................................................3-14

3.6 Overstory tree diameter map units .................................................................3-15

3.7 Map attribute accuracy goals and requirements .............................................3-16

3.8 Minimum map feature standard......................................................................3-17

3.9 Horizontal accuracy requirements ..................................................................3-17

3.10 Map update frequency ..................................................................................3-18

3.11 Technical group, map unit, and map feature relationship example..............3-20

3.12 Physiognomic type classification taxonomic units and map units...............3-22

3.13 Dominance type classification taxonomic units and map units...................3-23

3.14 Tree canopy cover classification technical groups and map units ...............3-24

3.15 Combined dominance type and tree canopy cover classification 

map units........................................................................................................3-25

3.16 Mid-level mapping methods .........................................................................3-28

3.17 Base-level mapping methods........................................................................3-32

3.18 Available digital image data types ................................................................3-36

3.19 Photographic scales and resolution necessary for vegetation mapping .......3-37

3.20 Data sources and methods for map feature delineation ...............................3-41

3.21A Aggregation logic—if physiognomic order is different than any 

adjacent map feature ......................................................................................3-42

3.21B Aggregation logic—if physiognomic order is the same as at least 

one adjacent map feature ...............................................................................3-42

3.22 Error matrix example....................................................................................3-51
xii Existing Vegetation Classification & Mapping Technical Guide
Section 1. Existing Vegetation Classification and

Mapping Framework

1.1 Introduction

The U.S. Department of Agriculture (USDA) Forest Service manages 156 national

forests and 20 national grasslands. These 191 million acres represent a variety of landscapes and ecosystems. Classification and mapping of vegetation are fundamental to the

stewardship, conservation, and appropriate use of these resources.

Existing vegetation is the plant cover, or floristic composition and vegetation structure, occurring at a given location at the current time. Existing vegetation is the primary

natural resource at the heart of almost everything the Forest Service does and is the

resource on which the agency spends the most money for inventories and assessments.

Existing vegetation, however, has historically lacked consistent standards for classification and mapping. As a result, vegetation descriptions and maps have not been sharable

across unit boundaries.

When classification and mapping of existing vegetation are undertaken, this protocol

establishes Forest Service standards and procedures for those activities. This technical

guide is authorized by the Forest Service Manual (FSM) 1940 and has been developed

according to direction in the Forest Service Handbook (FSH) 1909.

Read section 1 of this technical guide to provide context before reading sections 2 or 3.

1.1.1 Organization of Technical Guide

Section 1 of this technical guide describes the agency business needs that require existing

vegetation information and the strategy and concepts of the protocol. Section 1 also

provides the overall context and strategy for sections 2 and 3. Section 2 addresses floristic

classification of existing vegetation and the relationship of floristic vegetation types to

the Federal Geographic Data Committee (FGDC) 1997 physiognomic classification

standard. Section 3 describes hierarchical mapping of existing vegetation at multiple

levels. For definitions of terms used in this guide, see the Glossary.

This guide does not address quantitative inventory or monitoring of existing vegetation.

It also does not address classification or mapping of potential natural vegetation (PNV).

PNV classification and mapping protocols will be addressed in other technical guides.

1.1.2 Vegetation Classification Standards

The FGDC National Vegetation Classification Standards (NVCS) established a hierarchical existing vegetation classification with nine levels (FGDC 1997). The seven upper

Existing Vegetation Classification & Mapping Technical Guide 1-1
1-2 Existing Vegetation Classification & Mapping Technical Guide

levels are primarily based on physiognomy. The two lowest levels, alliance and association,

are based on floristic attributes. The Forest Service vegetation classification protocol

contained in this technical guide is compatible with the 1997 FGDC standards for physiognomic classification and is also as compatible as possible with the forthcoming

FGDC floristic classification standards, which were drafted by the Ecological Society of

America (ESA) Panel on Vegetation Classification (Jennings et al. 2004). 

Section 1.3.1 defines associations and alliances. Sections 2.2.4 and 2.2.5 describe

classification criteria for associations and alliances, respectively.

1.1.3 Vegetation Mapping Standards

No FGDC standard currently exists for vegetation mapping. This protocol provides

standards for developing vegetation geospatial databases and associated maps at four

hierarchical levels that support the various business functions of the Forest Service.

The four hierarchical map levels identified represent a gradient of thematic and

spatial detail. The coarsest level is designed to efficiently meet broad analysis needs; the

finest level is designed to provide more geographically precise and detailed vegetation

information. The defined map levels will help determine the information generally necessary at various functional levels of the Forest Service and set expectations for data

content, consistency, and accuracy. Section 1.3.2.2 describes each map level and summarizes general characteristics, related functional areas, and supported business requirements. Although local business needs may necessitate detailed mapping of nonvegetated

areas, this protocol is not intended to provide comprehensive guidance on performing

this task.

1.2 Background and Objectives

1.2.1 Existing Vegetation Information Uses

Ecosystem assessment and land management planning at national and regional extents

require consistent standards for classification and mapping of existing vegetation. An

existing standardized vegetation classification system provides a consistent framework

for cataloguing, describing, and communicating information about existing plant communities. The Forest Service does not have the resources to develop a separate classification

or map for every issue land managers face. Therefore, the Forest Service must describe

and map fundamental units of vegetation that can be interpreted to address numerous

inquiries. The net value of using standardized existing vegetation classifications and maps

is improved efficiency, accuracy, and defensibility of resource planning, implementation,

and activity monitoring. Hierarchical classification and multilevel mapping of existing

vegetation provide the appropriate level of detail for each issue. 
Existing Vegetation Classification & Mapping Technical Guide 1-3

Existing vegetation classifications and maps provide much of the information needed to

perform these tasks:

• Describe the variety of vegetation communities occupying an area.

• Characterize the effect of disturbances or management on species including threatened

and endangered species and community distributions.

• Identify realistic objectives and related management opportunities.

• Document successional relationships and communities within PNV or ecological types.

• Streamline monitoring design and facilitate extrapolation of monitoring interpretations.

• Assess resource conditions, determine capability and suitability, and evaluate forest

and rangeland health.

• Assess risks for invasive species, fire, insects, and disease.

• Develop and describe fire and fuels related analysis products (e.g., Fire Regime

Condition Classes).

• Conduct project planning and watershed analyses, and predict activity outcomes at

the project or Land and Resource Management Planning scales.

• More effectively communicate with Forest Service partners, stakeholders, and neighbors.

Implementation of Forest Service policies and regulations requires knowledge of

current vegetation composition, structure, and patterns that are provided through existing

vegetation classifications and maps. Some examples are listed below. 

• Sustainability: Planning Rules (36 CFR 219)—Evaluating and describing current

status of ecosystems and species diversity and viability.

• Suitability and capability: National Forest Management Act of 1976 (NFMA) (16

U.S.C. 1604[g])[3][b])—Evaluating and describing diversity of plant and animal

communities based on the suitability and capability of the land area.

• Noxious weeds and undesirable plants inventory: FSM 2080. 

• Rangeland management: FSM 2210, FSH 2209.13, chapter 90—Existing vegetation

composition and structure is used in conjunction with PNV to determine ecological

status, describe diversity of habitats, and describe desired future conditions.

• Threatened/endangered/sensitive species: FSM 2670—Description of current habitats for plant and animal species based on current vegetation composition, structure,

and patterns.

• Benchmark analysis: FSM 1922.12—Benchmark analysis provides baseline data to

formulate and analyze alternatives. Estimates of forests’ physical, biological, and

technical capabilities to produce goods and services require existing vegetation

information. Analysis is conducted according to 36 CFR 219.12 (e)(1).
1-4 Existing Vegetation Classification & Mapping Technical Guide

1.2.2 Relationship of Existing and Potential Natural Vegetation

Existing vegetation information alone cannot answer questions about successional relationships, historical range of variation, productivity, habitat characteristics, and responses to

management actions. These questions can be addressed only by combining information

about PNV, existing vegetation, and stand history. An existing vegetation classification

inherently lacks information on the above topics because it describes the vegetation present

at only a single point in time. The current plant community reflects the history of a site.

This history often includes geologic events, geomorphic processes, climatic changes,

migrations of plants and animals in and out of the area, natural disturbances, chance weather

extremes, and numerous human activities. Because of these factors, existing vegetation

seldom represents the potential under current environmental conditions.

PNV is “the vegetation...that would become established if all successional

sequences were completed without interference by man under the present climatic and

edaphic conditions.” (Tüxen 1956, as cited in Mueller-Dombois and Ellenberg 1974).

PNV classifications are based on existing vegetation, successional relationships, and

environmental factors (e.g., climate, geology, soil) considered together. This approach

requires understanding of species autecology and successional dynamics of plant communities. PNV classification uses information on structure and composition similar to

that needed for existing vegetation classification, but with greater emphasis on composition and successional relationships. 

Existing vegetation and PNV classifications and maps are both important, but address

different questions. They are best viewed as complementary and synergistic, rather than

mutually exclusive. Existing and PNV classifications can be done together as shown by

Mueggler’s (1988) classification of aspen forests in the Intermountain Region. Many

people request existing vegetation information, but expect it to include environmental

and successional relationships without fully understanding the implications. In reality,

land managers need information about both existing and potential natural vegetation to

assess resource conditions and evaluate management options.

1.2.3 Vegetation Classification Business Requirements

Classification is the process of grouping of similar entities together into named types or

classes based on shared characteristics. Vegetation classification consists of grouping a

potentially infinite number of stands or plots into relatively few vegetation types. A vegetation type is a named category of plant community or vegetation defined on the basis

of shared floristic and/or physiognomic characteristics that distinguish it from other

kinds of plant communities or vegetation. Definition of vegetation types makes meaningful generalizations about each type possible, thus reducing complexity and furthering

communication while maintaining meaningful differences among types.
Existing Vegetation Classification & Mapping Technical Guide 1-5

To meet the business requirements of the Forest Service, a floristic classification of

existing vegetation must have the following qualities:

• The classification system must eventually encompass all plant communities on

National Forest System (NFS) and adjoining lands.

• The classification system must be based on inherent vegetation attributes such as

composition, dominance, physiognomy, and structure. Solely abiotic features cannot

distinguish types.

• The classification system must be hierarchical with varying levels of detail available

to address management issues and guide vegetation mapping at multiple levels.

• The classification system must employ a simple dichotomous key with unambiguous

criteria so that all users can consistently identify the vegetation types.

• The classification categories must be based on collection and analysis of plot data to

ensure that they are precisely defined and mutually exclusive.

• The classification categories must be clearly defined, exhaustive, and mutually

exclusive to facilitate communication and sharing of information.

The above requirements constitute guiding principles for developing floristic vegetation types for use on NFS lands. These requirements are consistent with the FGDC’s

guiding principles for vegetation classification (FGDC 1997) listed in appendix 1A.

1.2.4 Vegetation Mapping Business Requirements

Vegetation mapping is the process of delineating the geographic distribution, extent,

and landscape patterns of vegetation types and/or structural characteristics. Maps are the

most convenient and universally understood means to graphically represent the spatial

arrangement and relationships among features on the earth’s surface (Mosby 1980).

Accurate and up-to-date maps of existing vegetation are commonly used for inventorying,

monitoring, and managing numerous resources on national forests.

Consistent mapping of vegetation types requires that a scientific classification of

existing vegetation be developed first because classification defines the entities to be

mapped. Any map based on vaguely defined types is inconsistent, hard to validate, and

difficult to compare with other vegetation maps. The knowledge gained and organized

through the classification process helps determine what spatial vegetation information is

needed to address land management issues. (See tables 1.3 and 1.4 for more information

on the relationship between classification and mapping.) Mapping may reveal gaps in a

classification that require development of new vegetation types or refinement of existing

types through additional data collection and analysis.

The most important part of designing and implementing a mapping project is establishing the mapping objectives in the context of the land management issues to be

addressed. Selection of the level of vegetation type (e.g., association) and the structural
1-6 Existing Vegetation Classification & Mapping Technical Guide

characteristics (e.g., canopy cover) used to define the mapped categories are a direct

function of vegetation mapping objectives. To meet the business requirements of the

Forest Service, maps of existing vegetation must have the following qualities:

• The vegetation characteristics used as map unit design criteria and their thematic resolution must be appropriate for depiction at the selected map level, and the selected

level must be appropriate for the attributes.

• The vegetation types or classes used in designing map units should be based on a

classification of existing vegetation, as described in section 1.2.3.

• The floristic composition of map units must be described in terms of clearly defined

existing vegetation types.

• At any given mapping level, the floristic resolution should be based on the level of

the existing vegetation hierarchy needed to address management issues.

• To the degree possible, finer map units should be capable of aggregation into broader map units based on the vegetation classification hierarchy.

• The mapping system must be hierarchical with varying levels of detail available to

address management issues at multiple scales over extensive areas.

• The map units must be mutually exclusive and exhaustive.

• The mapping process must be repeatable and consistent. 

• The map product must be of suitable accuracy for its intended uses. 

The above requirements constitute guiding principles for mapping existing vegetation on NFS lands.

1.2.5 Protocol Objectives

The objective of this technical guide is to provide direction for developing existing vegetation classification and map products that are consistent and continuous across the

landscape and responsive to the business needs of the Forest Service. The Forest Service

is directed to manage vegetation for a variety of social and economic purposes while

maintaining the integrity of ecosystem components and processes at national, regional,

and local scales. This direction requires standardized vegetation maps at multiple scales

across all NFS lands. The most effective way to standardize vegetation mapping is to

base map units at all scales on a standardized hierarchical vegetation classification.

Doing so will enhance the ability of the Forest Service to aggregate maps across large

geographic areas for spatial analysis of national, regional, or multiforest issues.

Standardized vegetation classification and mapping will also facilitate developing and

populating corporate databases.
Existing Vegetation Classification & Mapping Technical Guide 1-7

1.3 Protocol Overview

The existing vegetation protocol consists of two distinct but related processes: classification

and mapping. Vegetation classification defines and describes vegetation types based on

physiognomy and floristic composition. Vegetation mapping spatially depicts the distribution

and pattern of vegetation types and/or structural characteristics. Because of the limitations

of mapping technology, a one-to-one relationship rarely exists between vegetation types

and vegetation map units. Mapping entails trade-offs among resolution, accuracy (both

thematic and spatial), and costs. The goal is constrained optimization, not perfection.

1.3.1 Vegetation Classification Concepts and Definitions

Classification is the process of grouping of similar entities together into named types or

classes based on selected shared characteristics. Classification is a fundamental activity of

science and an integral part of human thought and communication (Mill 1872, Buol et al.

1973, Gauch 1982). Classification is how we assimilate and organize information to produce

knowledge. “When we have a definition for anything, when we really have studied its nature

to the point where we can say that it is this and not that, we have achieved knowledge”

(Gerstner 1980, as cited in Boice 1998). Classification is a form of inductive reasoning that

“establishes general truths from a myriad of individual instances” (Trewartha 1968). Even if

classification categories are conceptual or abstract rather than absolute facts, they serve to

formulate general truths based on numerous observations.

A class is “a group of individuals or other units similar in selected properties and

distinguished from all other classes of the same population by differences in these properties” (Buol et al. 1973). The properties selected as the basis for grouping individuals

into classes are called differentiating characteristics (Buol et al. 1973). Two fundamental approaches to selecting differentiating characteristics exist; each approach produces

a different kind of class (Mill 1872) and a different kind of classification (Buol et al.

1973, Pfister and Arno 1980, USDA Soil Survey Division 1999).

A natural or scientific classification is a classification in which the differentiating

criteria are selected to “bring out relationships of the most important properties of the

population being classified, without reference to any single specified and applied objective” (Buol et al. 1973). In developing a scientific classification, “all the attributes of a

population are considered and those which have the greatest number of covariant or

associated characteristics are selected as the ones to define and separate the various

classes” (Buol et al. 1973). A set of classes developed through scientific classification is

referred to as a taxonomy (USDA Soil Survey Division 1999). A taxonomic unit (or

taxon) is a class developed through the scientific classification process, or a class that

is part of a taxonomy.
1-8 Existing Vegetation Classification & Mapping Technical Guide

A technical classification (or technical grouping) is a classification in which the

differentiating characteristics are selected “for a specific, applied, practical purpose”

(Buol et al. 1973, Pfister and Arno 1980). The resulting classes are called technical

groups. In contrast to natural classifications, technical classifications are based on one

or a few properties to meet a specific interpretive need instead of considering all the

properties of the population. 

This technical guide provides direction for developing floristic taxonomic units and

technical groups based on vegetation structure. Both types of classes are used for a variety

of analysis applications that support the business needs of the Forest Service. 

1.3.1.1 Floristic Taxonomic Units

Vegetation classification consists of grouping a potentially infinite number of stands or

plots into relatively few vegetation types. A vegetation type is a named class of plant

community or vegetation defined on the basis of selected shared floristic and/or physiognomic characteristics that distinguish it from other classes of plant communities or

vegetation. Vegetation types are taxonomic units developed through the scientific classification process described above. Scientific classification makes meaningful generalizations

about each vegetation type possible, thus reducing complexity and furthering communication

while maintaining meaningful differences among types (Pfister and Arno 1980).

Members of a vegetation type (e.g., plots or stands) should be more similar to each

other (in aggregate) than they are to members of other vegetation types. Three different

levels of vegetation taxonomy are widely used in scientific vegetation classification:

association, alliance, and dominance type. These levels are defined below.

An association (or plant association) is “a vegetation classification unit defined on

the basis of a characteristic range of species composition, diagnostic species occurrence,

habitat conditions, and physiognomy” (Jennings et al. 2004). The FGDC standard specifies

that the term association “refers to existing vegetation, not a potential vegetation type.”

In other words, association does not necessarily refer to a climax plant community. This

usage predominates in vegetation ecology (Krebs 1972, Mueller-Dombois and Ellenberg

1974, Barbour et al. 1980, Collinson 1988). In contrast, the Forest Service (USDA Forest

Service 1991) and Natural Resources Conservation Service (NRCS) (USDA NRCS

1997) use the term “plant association” to refer to a climax or potential natural plant

community, following Daubenmire (1968). The FGDC standard mandates that the terms

“association” or “plant association” not be used to imply a climax plant community.

Classifying PNV at the association level of vegetation taxonomy, however, is acceptable.

An alliance is “a vegetation classification unit containing one or more associations

and defined by a characteristic range of species composition, habitat conditions, physiognomy, and diagnostic species, typically at least one of which is found in the uppermost
Existing Vegetation Classification & Mapping Technical Guide 1-9

or dominant stratum of the vegetation” (Jennings et al. 2004). Because an alliance is a

grouping of associations, plot data must be collected and analyzed and associations

classified before alliances can be defined. Classification of alliances, therefore, requires

the same level of data collection as classification of associations.

A dominance type is “a recurring plant community defined by the dominance of

one or more species which are usually the most important ones in the uppermost or

dominant layer of the community, but sometimes of a lower layer of higher coverage”

(Gabriel and Talbot 1984 as cited in Jennings et al. 2004). Dominance types have been

widely used in the development of map units where remote sensing imagery is the

primary basis for map feature delineation. “Determining dominance is relatively easy,

requiring only a modest floristic knowledge. However, because dominant species often

have a geographically and ecologically broad range, there can be substantial floristic

and ecologic variation within any one dominance type” (Jennings et al. 2004).

Dominance types can be developed more rapidly than associations or alliances, but

typically provide less information for land managers. 

1.3.1.2 Structural Technical Groups

Structural classes are technical groups developed to provide the basis for analysis applications and specific management interpretations. This protocol addresses the use of

structural classes to describe and map three attributes of vegetation structure: vegetated

cover, tree canopy closure, and overstory tree diameter. These attributes are defined

below. The technical groups or classes used to describe these attributes are presented in

tables 3.5, 3.6, and 3.7, respectively. 

Vegetated cover is the relative percentage of nonoverlapping vegetation cover, a

bird’s eye view as seen from above in a delineated area. Vegetated cover in a delineated

area will not exceed 100 percent.

Tree canopy closure is the total nonoverlapping tree canopy in a delineated area as

seen from above. The sum of all tree canopy cover within a delineated area will not

exceed 100 percent. Tree canopy closure below 10 percent is considered a nontree type. 

Overstory tree diameter is the mean diameter at breast height (4.5 feet, or 1.37

meters, above the ground) for the trees forming the upper or uppermost canopy layer

(Helms 1998). Tree size class is determined by calculating the diameter (usually at

breast height) of the tree of average basal area (Quadratic Mean Diameter [QMD]) of

the top story trees that contribute to canopy closure, i.e., tree cover as seen from a bird’s

eye view from above. Top story trees are those trees that receive light from above and at

least one side; these are the open grown, dominant, and codominant trees.
1-10 Existing Vegetation Classification & Mapping Technical Guide

1.3.2 Vegetation Mapping Concepts and Definitions 

Two fundamental mapping concepts are presented in the following sections and form the

basis for the map product standards defined in section 3. These fundamental concepts are

the relationship between vegetation classification and mapping and mapping at multiple

levels to address differing information needs. 

1.3.2.1 Relation of Vegetation Classification to Mapping

Consistent mapping of vegetation types requires that a vegetation classification be developed

beforehand. Vegetation mapping is the process of delineating the geographic distribution,

extent, and landscape patterns of vegetation types and/or structural characteristics.

Patterns of vegetation types are best recognized after the types have been defined and

described. Maps based on vaguely defined types are inconsistent, hard to validate, and

difficult to compare with other vegetation maps.

A vegetation map unit is a collection of areas defined and named the same in

terms of their component taxonomic units and/or technical groups (adapted from USDA

Soil Survey Division Staff 1993). Vegetation map units can be based on physiognomic

or floristic taxonomic units and structural technical groups, or combinations of these units

or groups. These taxonomic units and technical groups provide the basis for vegetation

maps that are consistent with the mapping objectives, appropriate for the map level being

produced, and within the limitations of mapping technology. Selecting the vegetation

types and structural classes to be depicted by the map is accomplished through the map

unit design process. 

Map units are designed to provide information and interpretations to support resource

management decisions and activities. The map unit design process establishes the criteria

used to aggregate or differentiate vegetation taxonomic units and technical groups to define

map units. A map unit comprises one or more taxonomic units or technical groups. The criteria

used to aggregate or differentiate within physiognomic types, floristic types, or structural

classes to form map units depends on the purpose of, and the resources devoted to, any particular mapping project (Jennings et al. 2004). For example, map units designed to provide

information on existing forest structure to characterize wildlife habitat or fuel condition

would be based on a combination of tree canopy cover and overstory tree diameter technical

groups. The map unit design process is more complex for vegetation types than for structural

characteristics. The mapping standards for vegetation cover, tree canopy closure, and tree

diameter described in section 3 represent general-purpose map unit designs for each structural

characteristic at all map levels; although local information needs may occasionally require

exceeding the standards.

Map units are depicted on maps within map features. Map features are individual

areas or delineations that are nonoverlapping and geographically unique (e.g., polygon

delineations or region delineations). Typically, one map unit is repeated across the land-
Existing Vegetation Classification & Mapping Technical Guide 1-11

scape in many individual map feature delineations. The map feature delineation process

should be based on the map units identified in the map unit design process. A more

detailed discussion and examples of the relationship among taxonomic units/technical

groups, map units, and map features are included in section 3.2.2.

1.3.2.2 Map Levels

Maps are developed and used at multiple resolutions and are best represented by a hierarchical

series of map products. In this technical guide, these products are described as map levels.

Four hierarchical map levels are identified that represent a gradient of thematic and spatial

resolution. Table 1.1 illustrates the business requirements and applications, and table 1.2

presents characteristics of these map levels. The four map levels are as follows:

• National. National, the coarsest level in the map hierarchy, is intended to store and

depict data at a nationwide or global extent. Map products at this level typically will

have broad map classes and coarse spatial representation. Products at this level may

be developed programmatically or aggregated from existing lower level products

where feasible.

• Broad. Broad-level products are intended to support State, multistate, or regional

information needs. Products at this level may be developed programmatically or

aggregated from existing products.

• Mid. Mid-level products are intended to support forest and multiforest information

needs including forest planning, forest/region resource assessment and monitoring,

and fire/fuels modeling. Products at this level provide a synoptic and consistent view

of existing vegetation across all ownerships within the map extent. They typically are

developed programmatically from remotely sensed data and field data. Standard

base-level maps, where they exist, should be considered for integration into mid-level

map products.

• Base. Base-level products support local forest and district information needs and

represent the highest thematic detail and spatial accuracy. Products at this level are

needed for most project planning and implementation. Base-level information is the

least likely of all levels to be spatially extensive due to the cost of development;

however, it offers the most flexibility for upward integration within the map hierarchy.

Products at this level are typically developed from large-scale, remotely sensed data

and field data.

These four map levels will help to determine the information necessary for various

organizational levels of the Forest Service and set the expectations for data content, consistency, accuracy, and development costs. The national level is intended to efficiently

meet the broadest analysis needs; the base level is intended to provide geographically

precise and detailed vegetation information. 
1-12 Existing Vegetation Classification & Mapping Technical Guide Table 1.1. Existing vegetation map levels, business requirements, and applications. Map Extent National (millions of sq. mi) State or multistate or (20+ million acres)

Forest ormultiforest(50,000+acres)5th/6thHUCWatershedor ProjectArea (<50,000acres)

Forest Service

program 

areas 

Forest Inventoryand Analysis (FIA),Resource PlanningAct (RPA),InternationalForestry, Fire,Forest HealthMonitoring (FHM)RPA, FIA, Fire,FHMForest Planning andMonitoring, Fire,FIAProject Planning,Forest PlanImplementation,Land Treatments

Map

Level

1:

National

2:

Broad

3:

Mid

4:

Base

Forest Service

business 

requirements

National StrategicInventory (FIAPhase I), ForestCover, Forest andRangelandHealth/SustainabilityBioregional assessments, conservation strategies(region/subregion)Forest/multiforestplanning/monitoring, 4th/5th HydrologicalUnit Code (HUC)WatershedAssessments,National Fire PlanImplementation(Forest Level) Forestand RangelandHealth Assessments,Terrestrial andAquatic HabitatAssessmentsForest Plan Implementation ProjectPlanning and LandTreatments, e.g.:• Fuel Treatments• Grazing Mgt.• Timber Mgt.• Habitat Mgt.Range AnalysisStand ExamsEffectivenessMonitoring 

Ecological 

unit 

hierarchy

Division, provinceSection, subsectionLandtype associationLandtype, landtype phase

Ecological 

analysis scale

(range)

ECOMAP 1997

1:30,000,000 to1:5,000,000; genpoly size10,000–100,000 sq.mi1:7,500,000 to1:250,000; gen polysize 10–1,000 sq. mi1:250,000 to1:60,000; gen polysize 1,000–10,000acres1:60,000 to1:24,000; gen polysize < 1,000 acres

Potential natural

vegetation 

classification 

Class and subclassSeriesSeries, climax plantassociation (sensuDaubenmire)Climax plant associations and phases(sensu Daubenmire)

Existing 

vegetation 

classification

NVCS class andsubclass, MajorLand RenewableResource Areas(MLRA)Dominance types,alliances (e.g.,Society for RangeManagement[SRM)], Society ofAmerican Foresters[SAF] cover types)Dominance types,alliances, (associations optional whereneeded)Alliances, associations

Existing 

vegetation map

unit design

National LandCover Database,NVCS class andsubclassDominance typegroups, alliancegroupsDominance types,alliances, alliancegroups and/or complexes, canopycover groups,size/height groups(e.g., VegetationStand Structure[VSS])Alliances, association, associationcomplexes, canopycover classes,size/height classes,vertical and horizontal structure

Existing 

vegetation map

product examples

National Land CoverDatabaseSAF forest typemap, Gap AnalysisProgram (GAP)R5 Classificationand Assessment withLandsat of VisibleEcological Groupings(CALVEG)California WildlifeHabitat Relationships (CWHR), R1Satellite Image LandClassification(SILC) 1 and 3,GAP, National Wetlands Inventory(NWI)Resource photointerpretation maps,stand maps (e.g., R8ContinuousInventory of StandConditions [CISC],R2 CommonVegetation Unit[CVU],range allotment analysis maps 

Data sources/

Sampling 

protocols

Forest healthMonitoring (FHM),FIA, NationalResearch Institute(NRI) FHM, FIA, NRIFIA intensified 

plots, compartmentexams,

field trainingdata plotsStand exams, rangeland protocols,TerrestrialEcological UnitInventory (TEUI)integrated plots 
Existing Vegetation Classification & Mapping Technical Guide 1-13

The four map levels differ in thematic and spatial resolution. Thematic resolution

is the level of categorical detail present in a given map unit; spatial resolution is the

measure of sharpness or fineness in spatial detail. To the extent possible, a nested thematic

and spatial relationship should exist between map levels for geographically coincident

map products. Although a seamless data hierarchy currently may not be feasible across

the entire agency, the objective is that maps developed across administrative units for

similar purposes will be comparable and reliable for conjunctive analysis. Vegetation

maps used by regional and national functions are expected to depict information consistent with local maps that follow this protocol. In practice, coarse data will sometimes be

used locally and specific information used nationally, which emphasizes the need for

data consistency and compatibility. 

These four map levels are not intended to be the sole definitions of the vegetation

map products required to meet the business needs of the Forest Service. The standards

defined in section 3 for each map level are the minimal requirements to achieve each

level and can be exceeded spatially and/or thematically. Informational requirements may

dictate the need for a vegetation map that contains elements of two map levels (e.g., mid

and base) or include information not identified in the standards section of this protocol.

In other words, view these map levels as minimal standards, not constraints.

1.3.2.3 Relation of Map Levels to Map Scale 

To differentiate the concepts of map level and map scale, a brief explanation of map

scale is necessary. Based on historical use in a vegetation-mapping context, it has

become easy to incorrectly use scale when referring to the detail depicted on a map.

The term scale actually describes the proportion that defines the relationship of a map,

Table 1.2. Existing vegetation map levels and characteristics.

Map

Level

National

Broad

Mid

Base

Typical map

extent

National (millions

of square miles)

State or multistate

(20+ million acres)

Forest or 

multiforest

(50,000+ acres)

5th/6th HUC

watershed or 

project area

(<50,000 acres)

Minimum 

mapping feature

area (acres)

500

20

5

5

Suggested 

update 

frequency

5–10 years

5–10 years

1–5 years

1–5 years

Required 

physiognomic

map attributes

Division, order,

and class

Division, order,

class, and subclass

Division, order,

class, and subclass

Division, order,

class, and subclass

Number of

required total

tree canopy 

closure classes

0

3

4

10

Number of

required 

overstory tree

diameter classes

None

None

5

7

Required 

floristic map

attributes

None

Cover types and

cover type groups

Cover types 

and regional 

dominance types

Cover types,

regional 

dominance types

and alliances
1-14 Existing Vegetation Classification & Mapping Technical Guide

image, or photograph to that which it represents, such as distance on the ground

(Robinson et al. 1978). For example, on Forest Service primary base maps, a distance of

1 foot on the map represents 24,000 feet on the ground and is represented by the scale

proportion of 1:24,000. Based on this definition, the term is only applicable when the

representation is fixed, such as on a printed map or image. Scale is not valid for geospatial

datasets that have no fixed representation. Because geospatial datasets are the standard

map products defined in section 3, the term “map level” replaces scale when identifying

vegetation datasets that can be effectively displayed at multiple scales but contain specific

thematic and spatial resolution. 

1.4 Roles and Responsibilities

Forest Service responsibilities for resource inventory and monitoring are outlined in

FSM 1940.04. Specific roles and responsibilities for classification and mapping of

existing vegetation are described below.

National 

• Provide direction for classification and mapping of existing vegetation that meets the

business needs of multiple disciplines.

• Develop classification and mapping standards for existing vegetation to facilitate

compatibility of vegetation types and maps across regional lines.

• Ensure that corporate database systems support the existing vegetation business needs.

• Coordinate with the Forest Service Inventory and Monitoring (I&M) Framework and

interagency classification and mapping activities.

• Support and evaluate regional implementation of existing vegetation classification

and mapping to ensure compliance with national standards.

• Ensure that existing vegetation classification is consistent with FGDC-adopted standards.

• Provide direction on interim classification and mapping of vegetation before the

FGDC floristic classification standard is completed.

• Ensure that regions are collecting data using approved NFS codes.

• Correlate vegetation types among regions, and ensure compatibility of descriptions

across regional boundaries.

• Maintain a national existing vegetation classification Web site to facilitate correlation.

Regional 

• Implement existing vegetation classification and mapping programs consistent with

national standards and protocols, and develop regional supplements as needed.
Existing Vegetation Classification & Mapping Technical Guide 1-15

• Develop existing vegetation classifications and maps to support resource assessments,

forest plan revisions, resource monitoring, and other business requirements as scheduled

in the regional strategic inventory plan.

• Coordinate with external cooperators and neighboring Regions to correlate vegetation

types.

• Conduct field reviews to ensure consistency and quality during accomplishment of

performance measures. 

• Correlate vegetation types in the Region, maintain a list of types in the Natural

Resource Information System (NRIS) database, and track the status of vegetation

classification and mapping in the region.

Forest 

• Implement the existing vegetation classification and mapping programs using

national standards and protocols and regional supplements.

• Implement classification and mapping projects on schedule and within budget.

• Collect appropriate field data to classify existing vegetation according to FGDC

standards.

• Provide quality control of data collection for classification and mapping projects; train

field crews to collect data in a manner consistent with established national protocols.

• Conduct accuracy assessments of existing vegetation maps.

• Ensure that vegetation classification and mapping information is used appropriately

in forest planning, assessments, and project implementation.

• Coordinate with local cooperators and neighboring Forest Service administrative

units to correlate vegetation types and maps.

• Correlate vegetation types and track the status of vegetation classification and mapping

in the forest.

• Publish final reports for vegetation classification and mapping projects.

• Enter and store all field-collected data in the NRIS database.

1.5 Relationship to Other Federal Programs and Standards

This section describes the relationship of the Forest Service existing vegetation protocol

to the FGDC NVCS (FGDC 1997), other Forest Service I&M protocols, and other

Federal and non-Federal programs.

All Federal agencies and programs that collect or produce vegetation data are under

the policy jurisdiction of the FGDC. Relationships between these agencies and programs

are governed by their joint accountability to the FGDC (OMB 1990, FGDC 1997). 
1-16 Existing Vegetation Classification & Mapping Technical Guide

1.5.1 Relationship to the FGDC National Vegetation Classification Standard

The protocol contained in this technical guide is designed to be compatible with the

FGDC NVCS published in 1997. The objective of that standard is as follows: 

The overall objective of the National Vegetation [Classification] Standard

(NVCS)...is to support the use of a consistent national vegetation classification

to produce uniform statistics in vegetation resources from vegetation cover data

at the national level. It is important that, as agencies map or inventory vegetated

Earth cover, they collect enough data accurately and precisely to translate it for

national reporting, aggregation, and comparisons. Adoption of the NVCS in

subsequent development and application of vegetation mapping schemes will

facilitate the compilation of regional and national summaries. (FGDC 1997).

1.5.1.1 History and Authority of FGDC

Office of Management and Budget (OMB) Revised Circular A-16 established the FGDC

in 1990. Its mission is to “promote the coordinated development, use, sharing, and

dissemination of surveying, mapping, and related spatial data” (OMB 1990). The FGDC

is authorized to “establish, in consultation with other Federal agencies and appropriate

organizations, such standards...as are necessary to carry out its government wide coordinating responsibilities” (OMB 1990).

Executive Order Number 12906 (Clinton 1994) designates the FGDC as the lead

organization to coordinate the development of the National Spatial Data Infrastructure

(NSDI), which is defined as “the technology, policies, standards, and human resources

necessary to acquire, process, store, distribute, and improve utilization of geospatial

data.” This Executive Order authorizes the FGDC to develop the standards required to

implement the NSDI and requires Federal agencies to meet those standards. The gravity

of this responsibility is best demonstrated with excerpts from Executive Order 12906:

NOW, THEREFORE, by the authority vested in me as President by the

Constitution and the laws of the United States of America ... it is ordered as

follows: ... Federal agencies collecting or producing geospatial data ... shall

ensure, prior to obligating funds for such activities, that data will be collected in

a manner that meets all relevant standards adopted through the FGDC process

[emphasis added] Executive Order Number 12906 (Clinton 1994).

1.5.1.2 Types of FGDC Standards

The FGDC establishes two kinds of standards: data and process (FGDC 1996). Data

standards “describe objects, features or items that are collected, automated, or affected

by activities or functions of agencies.... Data standards are semantic definitions that are
Existing Vegetation Classification & Mapping Technical Guide 1-17

structured in a model” (FGDC 1996). Process standards “describe how to do something,

procedures to follow, methodologies to apply, procedures to present information, or

business rules to follow to implement standards” (FGDC 1996). Five types of data

standards and 10 types of process standards exist (FGDC 1996). Those relevant to

existing vegetation classification are as follows:

• Data classification standards “provide groups or categories of data that serve an

application.... Examples are wetland and soil classifications” (FGDC 1996). In other

words, a data classification standard specifies and defines a set of categories that

must be used, or crosswalked to, by Federal agencies. The physiognomic levels of

the NVCS (FGDC 1997) are a data classification standard.

• Classification methodology standards “are the procedures to follow to implement

a data classification standard. It (sic) describes how data are analyzed to produce a

classification” (FGDC 1996). Classification methodology standards specify how to

develop a classification rather than specifying the categories of the classification.

The floristic levels of the NVCS (FGDC 1997) will be addressed by a classification

methodology standard.

1.5.1.3 FGDC National Vegetation Classification Standard Overview

The FGDC NVCS establishes a hierarchical existing vegetation classification with nine

levels. The top seven levels are primarily based on physiognomy. The two lowest levels,

alliance and association, are based on floristic attributes. Appendix 1B provides an

overview of the NVCS physiognomic hierarchy. Appendix 1C contains a draft key to the

five highest physiognomic levels.

The NVCS provides data classification, content, and collection standards for the

seven physiognomic levels of the NVCS. It specifies and defines the vegetation categories

making up the physiognomic hierarchy and requires Federal agencies to collect the data

attributes needed to identify the physiognomic categories. The FGDC Vegetation

Subcommittee is currently in the process of revising the physiognomic levels of the

NVCS (FGDC 2001a).

The NVCS provides minimal classification methodology, data collection, and quality

assurance standards for the floristic levels of the hierarchy. According to the NVCS, “A

comprehensive list of the nation’s floristic level vegetation types is currently a goal to be

pursued in the long term application of this standard” (FGDC 1997). The full development

of the floristic classification methodology standards is currently underway as Part II of

the current standard (FGDC 2001b). The ESA Panel on Vegetation Classification has

drafted the standards (Jennings et al. 2004).
1-18 Existing Vegetation Classification & Mapping Technical Guide

1.5.1.4 FGDC National Vegetation Classification Requirements

The NVCS provides the reason for a national vegetation classification standard: 

The purpose of the national standard is to require all federal vegetation classification efforts to have some core components that are the same across federal

agencies to permit aggregating data from all federal agencies. The NVCS does

not prevent local federal efforts from doing whatever they want to meet their

specific purposes. NVCS does require that when those local efforts are conducted,

they are conducted in ways that, among whatever else they do, they provide the

required core data [emphasis added] (FGDC 1997).

The NVCS further notes that “the adopted standards must be followed by all federal

agencies for data collected directly or indirectly (through grants, partnerships, or contracts)”

(FGDC 1997). The FGDC physiognomic data requirement clearly applies to all protocols

that involve classification or mapping of vegetation types. It also applies to any inventory

or monitoring protocol that identifies or documents vegetation types: “The NVCS

requires federally supported vegetation classification activities to collect data in ways

that permit the data to be useful for creating a classification according to NVCS requirements” (FGDC 1997).

This Forest Service protocol contained in this technical guide requires the collection

of all vegetation attributes (i.e., “core data”) needed to crosswalk field plots to the physiognomic categories of the NVCS (FGDC 1997). It does not require using the FGDC

physiognomic categories due to their impending revision (FGDC 2001a). The FGDCrequired physiognomic attributes are described in section 2.4.2 of this technical guide.

The NVCS does not establish floristic data standards because “Currently the policy

for applying the standard is only through the formation level” (FGDC 1997). The floristic

data requirements of this protocol have been coordinated as closely as possible with the

proposed FGDC floristic classification methodology standard as drafted by the ESA

Panel on Vegetation Classification (Jennings et al. 2004). All vegetation attributes

required by this protocol are described in section 2.4 of this technical guide.

Future FGDC revisions of the physiognomic levels of the NVCS and formal FGDC

adoption of a floristic classification methodology standard may necessitate revision of

this technical guide. Section 1.6 describes the revision procedures.

1.5.1.5 FGDC Classification and Forest Service Business Needs

The Forest Service is directed by the Forest and Rangeland Resource Planning Act of

1974 to inventory all forest land of the United States and by the National Forest

Management Act of 1976 to inventory all national forests. For inventory purposes, forest
Existing Vegetation Classification & Mapping Technical Guide 1-19

land is defined as those lands having at least 10-percent stocking, or formerly having

such tree cover, and occupying an area of at least 1 acre in size (USDA Forest Service

2002). For mapping, the agency defines forest land as having 10-percent canopy closure

of trees. This mapping definition, adopted as an interagency standard with the development

of the U.S. Geological Survey (USGS) Land Use Land Cover Classification System

(Anderson et al. 1976), is also consistent with the International Forestry definition of

forest land (UN-ECE/FAO 1997). 

The NVCS physiognomic class of closed canopy forest is defined as 60- to 100-percent

tree canopy closure, and the open tree canopy as 25 to 60 percent canopy closure. Both

classes are clearly forest lands by the Forest Service standard. Because of the gap from

10- to 25-percent tree canopy closure, an additional physiognomic class is needed to

meet the Forest Service business need related to forest inventory, monitoring, and land

management planning. For this technical guide, a physiognomic mapping category of

sparse tree canopy, defined as 10- to 25-percent tree canopy closure, will be added to

the physiognomic class level.

Additionally, arid shrublands in the Western United States are commonly classified

as shrubland types, having shrub cover of at least 5 percent (Hironaka et al. 1983,

Mueggler and Stewart 1980). In acrid ecosystems, 5- to 10-percent shrub cover has been

found to be ecologically significant in the classification and management of grasslands

(Daubenmire 1970). NVCS physiognomic standards fail to recognize these two critical

percent breaks at the physiognomic class level, using 25- to 100-percent cover for both

the shrubland and dwarf shrubland classes. To meet the inventory, mapping, and management business needs of the Forest Service, mapping categories for shrubland and

dwarf shrubland will be redefined as shrub- or dwarf-shrub-dominated lands with 10-

to 100-percent shrub cover. Trees must be less than 10-percent canopy closure.

For grasslands, an additional physiognomic map category of herbaceous shrub steppe

will be added and defined as herbaceous life form dominated with at least 10-percent

cover, and shrub and or dwarf shrub life form of at least 5-percent but less than 10-percent

cover. The cover requirements for the herbaceous physiognomic class will also be

reduced and redefined for mapping as herbaceous-life-form-dominated land with at

least 10-percent cover. Tree, shrub, and/or dwarf shrub life forms must be less than 10

percent cover. Using a 10-percent or lower cover break for shrubland and grassland

types is consistent with the National Park Service, for which several recent vegetation

alliance and association level classifications have been completed for Devils Tower

(WY) and Tuzigoot (AZ) National Monuments, as well as Badlands National Park, SD

(USGS and NPS, 2002).

These modifications and additions to the NVCS physiognomic class level will allow

the mapping of critical vegetation map unit categories necessary to fully meet the business

needs of the agency.
1-20 Existing Vegetation Classification & Mapping Technical Guide

1.5.2 Relationship to Other Forest Service Inventory and Monitoring Protocols

The overall objective of Forest Service I&M protocols “is to provide the ecological,

social, and economic information necessary for the Forest Service to achieve its mission

to sustain the health, diversity, and productivity of the nation’s forests and grasslands to

meet the needs of present and future generations” (USDA Forest Service 2002).

Inventory and monitoring of natural resources provide the ecological information

required by the Forest Service mission. In this context, inventory and monitoring are two

overarching processes:

• Inventory is the systematic acquisition, analysis, and organization of resource information needed for planning and implementing land management (adapted from

USDA NRCS 1997). 

• Monitoring is the systematic collection, analysis, and interpretation of resource data to

evaluate progress toward meeting management objectives (adapted from SRM 1989).

These two overarching processes comprise specific activities designed to answer basic

resource questions. These questions and activities are described in table 1.3, which illustrates

the overall structure of the Forest Service Inventory and Monitoring Framework.

Table 1.3. I&M framework.

Inventory—The systematic acquisition,

analysis, and organization of resource information needed for planning and implementing land management.

(adapted from USDA NRCS 1997)

Monitoring—The systematic collection,

analysis, and interpretation of resource data to

evaluate progress toward meeting management objectives. 

(adapted from SRM 1989)

What is it?

Where is it?

How much is there?

How is it changing over time?

Is it moving toward or away from management objectives?

Classification—The grouping together of

similar entities into named types or classes

based on shared characteristics.

Resource Mapping—The delineation of the

geographic distribution, extent, and landscape

patterns of resource types or attributes.

Quantitative Inventory—The objective

quantification of the amount, composition,

condition, and/or productivity of resource

types or parameters within specified levels of

statistical precision.

(adapted from Helms 1998)

Dynamic Sampling—The collection and

analysis of resource data to measure changes

in the amounts, spatial distribution, or 

condition of resource types or parameters

over time.

(adapted from Helms 1998)

Evaluation—The comparison of dynamic

sampling results to management objectives

consisting of predetermined standards,

expected norms, threshold values, and/or 

trigger points.

Overarching I&M process Basic resource question Specific I&M activity
Existing Vegetation Classification & Mapping Technical Guide 1-21

Table 1.4. Relationships of existing vegetation I&M activities to other Forest Service activities.

Basic questions

Task or activity

Relationships between

processes

Existing vegetation

classification

What is it?

Develop and describe vegetation types; create keys

to distinguish between

types.

Classification is a prerequisite for each of the other

three processes. The other

processes, especially mapping, can help validate

and refine a classification.

Existing vegetation

mapping

Where is it?

Delineate geographic 

distribution, extent, patterns, and juxtaposition of

vegetation types and/or

attributes. 

Use a standard vegetation

classification to develop a

map legend and to design

map units.

Quantitative 

vegetation inventory

How much is there?

Estimate the amount of

each vegetation type or

the values of vegetation

attributes, in a specific

area.

An inventory of vegetation types requires that a

classification be developed first. An inventory

can be generated from a

map by summing acres of

map units, polygons, or

components.

Vegetation

monitoring

Is it changing toward or

away from management

objectives?

Detect changes over time

in amounts of vegetation

types or values of vegetation attributes, and compare them to management

objectives.

Knowledge gained

through classification,

mapping, and quantitative

inventory helps develop

evaluation criteria and

monitoring methods.

Repeated mapping or

inventory can provide

monitoring data.

The inventory process includes three fundamental activities: classification, resource

mapping, and quantitative inventory. These activities produce basic information about

ecosystems and/or individual resources. These accumulated data and organized knowledge

are necessary to provide a credible scientific basis for establishing land management

objectives that are biologically and physically attainable.

The monitoring process includes dynamic sampling and evaluation. Dynamic sampling

measures changes in resources over time (Helms 1998). Evaluation compares these changes

to management objectives, threshold values for sustainability, and/or trigger points that

initiate specific management actions. The evaluation criteria and the sampling methods

are based on the body of knowledge produced by the inventory process.

Classification and mapping of existing vegetation are related to quantitative vegetation

inventory and vegetation monitoring. Table 1.4 describes each of these activities in terms

specific to vegetation (instead of the generic terms in table 1.3), explains the relationships

between them, and lists other vegetation protocols and processes that are related to these four

existing vegetation activities. These include classification and mapping of PNV and historic

vegetation, several Terrestrial Ecological Unit Inventory (TEUI) processes, and specific

existing vegetation monitoring and quantitative inventory protocols.

The sampling methods employed by the protocols listed in table 1.4 should be as

similar as possible to facilitate information sharing and simplify development of corporate
1-22 Existing Vegetation Classification & Mapping Technical Guide

Table 1.4. Relationships of existing vegetation I&M activities to other Forest Service activities. (continued)

Related activities or

processes

Existing vegetation

classification

• PNV classification 

• Ecological type 

classification

• Historic vegetation

classification

Existing vegetation

mapping

• PNV mapping 

• Landtype association 

(LTA) mapping

• Landtype mapping

• Landtype phase mapping

• Historic vegetation 

mapping 

• Fire regime condition 

class mapping

Quantitative 

vegetation inventory

• FIA

• Common stand exam

• Riparian inventory

• Old growth inventory 

• Range inventory

Vegetation

monitoring

• Forest health monitoring

• Range monitoring

• Riparian monitoring

• Invasive weed 

monitoring

• Threatened and 

endangered species (TES)

plant monitoring

Table 1.5. Comparison of sampling approaches for existing vegetation I&M activities.

Task or activity

Example attributes:

Sample location 

method

Sampling methods

Existing vegetation

classification

Develop and describe 

vegetation types; create

keys to distinguish

between types. 

• Physiognomy

• Floristics

• Composition

• Structure

Subjective

Uniform stand and site

conditions; not ecotonal.

Objective

Systematic placement

along environmental 

gradients, or random

placement

Reconnaissance or 

intensive. Vegetation and

environmental data

required for identifying

relationships.

Existing vegetation

mapping

Delineate geographic distribution, extent, patterns,

and juxtaposition of 

vegetation types and/or

attributes.

• Vegetation types

• Plant size classes

• Canopy cover

Subjective

Representative of a polygon or map unit.

Objective

Systematic or random

placement in a polygon or

map unit.

Reconnaissance or intensive. Vegetation and environmental data usually

collected. 

Quantitative 

vegetation inventory

Estimate the amount of

each vegetation type, or

the values of vegetation

attributes, within a 

specific area.

• Vegetation types

• Plant size classes

• Canopy cover

• Productivity

• “Health indicators” 

Subjective

Usually not appropriate.

Objective

Random or systematic

placement to provide statistical reliability.

• Usually intensive.

• Usually requires only 

vegetation data.

• Methods depend on 

objectives. 

Vegetation

monitoring

Detect changes over time

in amounts of vegetation

types or values of vegetation attributes, and compare them to management

objectives.

• Vegetation types

• Plant size classes

• Canopy cover

• Productivity

• “Health indicators”

Subjective

Located in benchmark 

or key areas of concern.

Objective

Located randomly or systematically in key areas.

• Usually intensive.

• Data collected 

depends on what is being 

monitored.

vegetation databases. Table 1.5 presents a generalized comparison of the sampling

approaches used in classification, mapping, quantitative inventory, and monitoring of

vegetation. It describes the kinds of attributes collected, selection of sampling locations,

and precision of sampling method.
Existing Vegetation Classification & Mapping Technical Guide 1-23

1.5.2.1 Relationship to Forest Service TEUI Protocol 

To provide the ecological context for making land management decisions, use the existing

vegetation classification protocol and TEUI protocol together. Existing vegetation classification and maps describe current vegetation composition, structure, and patterns.

TEUI provides ecological type classifications and defines land units where response to

disturbance processes and land management actions are expected to be similar based on

PNV and physical site characteristics (e.g., geology, climate, soil, and topography). 

Existing vegetation classifications and maps, when combined with ecological type

classifications and ecological unit maps, provide land managers a context for evaluating

ecological conditions and resource values (e.g., wildlife habitat, forage, watershed conditions, and timber) and selecting appropriate land management practices based on

ecosystem capability. Bourgeron et al. (1994) consider relationships between biotic

components and abiotic factors important for predicting management response of

ecosystems and landscapes under various management scenarios. Bailey et al. (1994)

describe the importance of combining existing vegetation maps with ecological unit

maps delineating land areas with similar potential for management to effectively assess

ecosystem health in land use planning. 

Predicting vegetation response or change as a function of various management scenarios or natural disturbance regimes requires associating existing vegetation classifications

with TEUI ecological type classifications and describing successional relationships and

dynamics. This requires classifying and describing the plant communities or vegetation

states that may be associated with an ecological type. State and transition diagrams and

succession models are being used by a variety of resource managers and specialists to

predict vegetation change in response to disturbance processes or management practices.

The state and transition diagram (Westoby et al. 1989, Stringham et al. 2001) is used to

describe how different disturbances or management practices (e.g., fire, flooding, grazing,

and insects), or stresses (e.g., drought, increased precipitation, climate change, and variability) affect changes or transitions from one plant community or state to another. Using

this existing vegetation classification protocol in development of state and transition

models facilitates prediction of changes in vegetation composition, structure, and pattern.

This improves the utility of TEUI for evaluation and determination of desired vegetation

objectives. 

Information derived from combining existing vegetation classification, descriptions,

and maps with TEUI provides the basis for selecting suitable areas for land use activities,

identifying and prioritizing areas for restoration activities, evaluating various land management alternatives, and predicting the affects of a given activity on ecosystem health

and resource condition. Existing vegetation classification and maps describe the range

of vegetation composition, structure, and plant diversity associated with ecological

types. This information can be used by land managers to assess and describe existing
1-24 Existing Vegetation Classification & Mapping Technical Guide

and potential resource conditions, define and describe desired vegetation conditions,

describe outcomes resulting from various management prescription scenarios, and

communicate environmental affects of land management planning alternatives.

Section 2 of this technical guide describes the methods used to develop vegetation

types that can be used to describe the plant communities and states associated with

ecological types that are developed according to the Terrestrial Ecological Unit

Inventory Technical Guide. 

1.5.3 Relationship to Other Federal Programs and Standards

All Federal agencies are required by Executive Order 12906 (Clinton 1994) to comply

with FGDC standards (see section 1.5.1.1). Coordination of existing vegetation classification efforts among agencies is possible only to the extent that each agency complies

with the NVCS (FGDC 1997). As lead agency for the NSDI vegetation theme (OMB 1990)

and chair of the FGDC Vegetation Subcommittee (FGDC 1997), the Forest Service must

make every effort to include all relevant Federal agencies in the development and implementation of the NVCS.

1.5.4 Relationship to Non-Federal Programs and Standards

FGDC standards are mandatory only for Federal agencies, but non-Federal governments

and private organizations are encouraged to participate in the continued development of

the NVCS (OMB 1990, Clinton 1994, FGDC 1997). As lead agency for the NDSI vegetation theme (OMB 1990) and chair of the FGDC Vegetation Subcommittee (FGDC

1997), the Forest Service must make every effort to include all interested non-Federal

organizations in the development and implementation of the NVCS.

1.6 Change Management

Process

This technical guide will be updated periodically based on interdisciplinary consultations

and the results of testing the products of the guide. Stimuli for change will include results

of national and regional field reviews, usage, and recommendations submitted to the

national program manager from the field.

Supplements

Supplementation of the protocol is delegated to regions but not to forest and grassland

supervisors. Regions may supplement the information in this technical guide with methods

or guidance required for meeting specific issues or needs of the Region, and as FGDC

standards and other programs change.
Existing Vegetation Classification & Mapping Technical Guide 1-25

Review

A cadre of experts will conduct a periodic review to determine how and when to make

changes. The classification and mapping protocols will be refined through a process of

peer review. This will be a continuous process coordinated by the Washington Office

Ecosystem Management Staff.

Update Schedule

After the protocol is finalized, the Existing Vegetation Mapping Technical Guide will be

updated as directed by the Washington Office Ecosystem Management Staff.
1-26 Existing Vegetation Classification & Mapping Technical Guide
Existing Vegetation Classification & Mapping Technical Guide 2-1

Section 2. Existing Vegetation Classification Protocol

2.1 Purpose

The purpose of this protocol is to produce a consistent classification of existing vegetation

across National Forest System lands that is compatible with the Federal Geographic Data

Committee (FGDC) National Vegetation Classification Standard (NVCS) and meets

business needs of the Forest Service. In the long term, this requires classification of

associations and alliances. In the short term, some business needs can be met through

classification of dominance types as provisional alliances (see section 2.2.5). This protocol

provides standards and guidelines for collection, analysis, and interpretation of data to

classify and describe associations, alliances, and interim dominance types based on the

guiding principles enumerated in section 1.2.3. 

2.2 Planning and Design

In this section: Overview of the vegetation classification process, classification concepts,

association and alliance criteria, and standards for documentation and correlation of

vegetation types

The FGDC NVCS (1997) indicates that “classification methods should be clear,

precise, where possible quantitative, and based upon objective criteria.... Classification

necessarily involves definition of class boundaries.” Kuchler (1973) states, “A scientific

classification must have definable units, described with the greatest possible precision

and consistency; there must be no exception to the rule.” 

2.2.1 Vegetation Classification Process

The process of classifying vegetation types consists of a preliminary stage (ideally)

performed once and an iterative stage usually repeated until the classification project is

completed. The process is outlined below, followed by a short discussion of each step.

Figure 2.1 is a diagram of the classification process.

Preliminary Stage

1. Review literature relevant to the ecology of the study area.

2. Evaluate available plot data for the study area.

3. Conduct reconnaissance of the study area.

4. Select classification criteria and descriptive attributes based on the purpose and 

taxonomic level of the classification.
2-2 Existing Vegetation Classification & Mapping Technical Guide

Figure 2.1. Flow diagram of vegetation classification process.
Existing Vegetation Classification & Mapping Technical Guide 2-3

5. Develop a sampling strategy consistent with the classification criteria that will 

encompass the full range of environmental factors in the survey area.

6. Select sampling methods based on the classification criteria and descriptive 

attributes.

Iterative Stage

7. Conduct field sampling using the strategy and methods developed above.

8. Analyze data using techniques consistent with the classification criteria.

9. Define vegetation types by interpreting the analysis results and developing a 

diagnostic key.

10. Characterize vegetation types by summarizing floristic and environmental data.

11. Field-test the diagnostic key and vegetation type descriptions.

Note: If the classification is inadequate, return to step 6 or 7, and repeat the cycle.

If it does work well and meets documentation standards, continue with step 12.

12. Develop ecological interpretations for each vegetation type.

13. Publish the classification, and add types to the Forest Service corporate database.

The iterative stage of the classification process is often referred to as successive

refinement because it involves repeated cycles of knowledge, questions, and observations.

Successive refinement is the basic working approach of community ecologists (Pfister

and Arno 1980, Gauch 1982). The preliminary stage of classification provides the starting

knowledge for the first iteration of successive refinement. 

2.2.1.1 Preliminary Stage

Literature review, data evaluation, and reconnaissance (steps 1 through 3) constitute

preparation for a classification project. They are essentially the same for associations,

alliances, and dominance types. Steps 4 through 6 produce a project plan for classification

development. Classification criteria and sampling approach differ for each level of

floristic classification (sections 2.2.4 and 2.2.5).

1. Review literature. The first step in developing a vegetation classification is reviewing the ecological literature relevant to the study area. Types of information include

the following:

• Synecological—Previous classifications of existing or potential vegetation from

adjacent areas. This includes vegetation data from the survey area, such as range

analysis transects and timber inventory plots.
2-4 Existing Vegetation Classification & Mapping Technical Guide

• Autecological—Literature on the physiology and life cycles of the predominant

plant species and their responses to environmental factors, natural disturbances,

herbivory, and management activities.

• Vegetation History—Literature describing historic natural and human-caused

disturbances of the vegetation in the study area or adjacent areas. Ideally this

includes information on the severity and extent of past disturbances, their effects

on vegetation, and responses of individual species.

• Botanical—Taxonomic keys and species lists for the survey area and adjacent

areas. This should include synonymous plant names and their authors, which may

be needed to interpret the above literature.

• Climatic—Precipitation maps, precipitation and snowfall data, air temperature

data, and soil moisture and temperature data (if available).

• Geologic—Literature on geologic parent materials, geomorphic processes, and

physiography of the study area, ideally including maps.

• Soils—Soil surveys, Terrestrial Ecological Unit Inventories (TEUI), or other studies

in the survey area. Studies from adjacent areas also may be useful, especially if

they address soil-vegetation relationships.

• Hydrologic—Studies of surface and subsurface water sources and flows in relation

to the study area. Data on water chemistry, including pH.

• Zoological—Natural history and current and historical distribution and abundance

of vertebrates and invertebrates that may affect the distribution, abundance, and

condition of plant species in the study area. This should include information on

herbivores (e.g., ungulates), keystone species (e.g., beavers), and other species

that may influence vegetation.

2. Evaluate existing plot data. In addition to relevant literature, review all plot data

available for the study area and evaluate its usefulness to the vegetation classification

project. Some plot data may be used directly to help develop the classification; others

may be useful only to help stratify the area for reconnaissance or sampling. Other

plots may provide descriptive data, such as site index or forage production, if they

can be assigned to a vegetation type after the classification is completed. Examples

of data include TEUI plots, range inventory and monitoring plots, stand exams, and

Forest Inventory and Analysis (FIA) plots.

3. Conduct reconnaissance. Reconnaissance consists of rapidly traversing the study

area looking for general features of the landscape and vegetation, such as predominant

plant species, geologic parent materials, landforms, and climatic patterns

(Daubenmire 1968). Reconnaissance provides an “on-the-ground” look at the same

factors mentioned in the literature review. Reconnaissance may include field-checking
Existing Vegetation Classification & Mapping Technical Guide 2-5

the accuracy and/or relevance of pre-existing plot data (step 2). The intensity, or level

of detail, employed in reconnaissance determines which sampling strategies (step 5)

can be used validly (Mueller-Dombois and Ellenberg 1974).

4. Select classification criteria. The purposes of the intended classification are important considerations in selecting classification criteria. Determine which vegetation

attributes will potentially be classification criteria and what additional data are needed

for descriptive purposes or to derive management interpretations. For example, if

managers want timber productivity estimates for each vegetation type, timber productivity data must be collected on at least a subset of the plots. Classification

criteria for associations and alliances are described in sections 2.2.4 and 2.2.5,

respectively. This step usually includes selection of analysis techniques appropriate

for the classification criteria chosen.

5. Develop sampling strategy. The sampling strategy determines how samples will be

distributed over the study area and what criteria will be used to locate sample plots.

Use the major environmental gradients identified through literature review and reconnaissance to stratify the survey area for sampling. At a minimum, stratify the study

area by elevation, landform, slope, aspect, geology, parent material, and vegetation

patterns noted during reconnaissance (see section 2.3). Locate individual sample plots

in areas of uniform vegetation and environment (FGDC 1997, Jennings et al. 2004).

6. Select sampling methods. Sampling methods are selected based on the classification

criteria and descriptive attributes chosen for the project. The major concerns in plant

community sampling are plot size, plot shape, and methods for measuring or estimating

species abundance. If similar vegetation has been classified in adjacent areas, seriously

consider the sampling methods used in those studies. As noted in step 4 above, other

plot data uses may require collecting additional attributes. Keep such additional

attributes to a minimum because they increase the time needed to sample a plot,

thereby reducing the number of plots available to develop the classification. Sampling

methods are described in section 2.4.

2.2.1.2 Iterative Stage

The iterative stage implements the project plan developed in the preliminary stage. Gauch

(1982) recommends performing a pilot study to refine the sampling and data analysis

methods. The first year of a classification project usually serves as a pilot study, even if

this was not intended. Refining the criteria and methods requires revisiting steps 4, 5,

and 6 of the classification process and revising the project plan. Carefully document any

changes made. Iterative refinement of a classification can continue or be reinitiated during

vegetation mapping.
2-6 Existing Vegetation Classification & Mapping Technical Guide

7. Perform field sampling. Field sampling consists of collecting data in accordance

with the sampling strategy using the chosen sampling methods. 

8. Analyze data. The analysis procedures used by community ecologists are designed

to detect patterns and relationships in a dataset, filter out noise, and eliminate outliers

(Gauch 1982). Patterns include repeating coordinated species abundances and groups

of samples with similar species composition. The patterns reflect relationships between

plant species or between species and environmental factors. Noise is noninterpretable

variation in species abundances that obscures patterns and relationships in the dataset.

Sources of noise include chance distribution and establishment of seeds, disturbance

effects, microsite variation, outliers, and misidentification of species. An outlier is a

sample with low similarity to all other samples in a dataset. 

9. Define vegetation types. Defining vegetation types requires interpreting the results of

data analysis in light of the biology of the species involved and the inherent limitations

of the numerical techniques used. The process of reducing noise and eliminating outliers may require deleting certain species and plots from the dataset and repeating the

analyses. Eventually, this process groups the samples in the dataset into tentative

vegetation types. Use the attributes that distinguish each group to develop a diagnostic

key for field identification of the preliminary vegetation types. The key is tested on

the entire dataset and revised as needed. See section 2.7 for vegetation type description

requirements.

10. Characterize vegetation types. Characterization entails describing the properties

and components of a category or class. After the vegetation types are defined,

species composition and environmental data are summarized to characterize the

types. A vegetation type description describes the central concept of the type and the

range of variation within the type. Such descriptions require several samples per type.

11. Field-test classification. Field-testing of the classification uses the key and descriptions

in the field to identify vegetation types. This often is performed concurrently with

field sampling during the next iteration of the classification process. The iterative

stage of the classification process is complete when the descriptions and keys work

well in the field for a variety of end users, and each type is adequately documented.

Ideally, the relationships of vegetation types to environmental factors and disturbances

are also documented. Correlation by the regional ecologist and peer review by other

ecologists must be incorporated into this step.
Existing Vegetation Classification & Mapping Technical Guide 2-7

12. Develop management interpretations. Management interpretations describe characteristics of each vegetation type that are relevant to land use and management

decisions. Some interpretations depend solely on attributes of the existing vegetation,

and others are a function of successional relationships to other vegetation types. After

the classification system is finalized, management interpretations for each vegetation

type are developed and a complete description of each type is written. As land managers

use the classification in conducting projects, they will obtain additional information

on how each vegetation type responds to various treatments. A vegetation classification

provides a way to organize this new information and retrieve it for application to

future projects. 

13. Publish the classification. After the classification is complete, publish a report that

includes vegetation type descriptions, diagnostic keys, and documentation of the

sampling and analysis methods used to develop the classification. For more details

on the contents of the report, see section 2.7. To provide scientific credibility, peer

review of the final manuscript is required and publication in a refereed forum is

preferred. The regional ecologist should oversee the peer review process and ensure

that new vegetation types are added to the corporate database.

2.2.2 Classification Approaches and Concepts

Two fundamentally different approaches are used to develop classifications. The “top-down”

or divisive method subdivides a group of objects based on differences among them. Most

divisive classifications use differences that are readily apparent to define the categories.

The “bottom-up” or agglomerative method defines types by grouping objects together

based on shared characteristics. This method accommodates and often requires detailed

observations of the objects to be classified. Table 2.1 compares these two approaches to

classification.

A classification can be either hierarchical or nonhierarchical. Both assign objects to

classes based on shared attributes; hierarchical classifications also group those classes

based on shared attributes. A hierarchy enables objects to be compared at various levels

of detail and expresses relationships between individual objects. A simple hierarchy can

assist in organizing and accessing information. A hierarchy may be better suited for

describing and mapping vegetation at multiple geographic scales (FGDC 1997); however,

the order in which criteria are used in the hierarchy greatly affects the usefulness of the

classification.
2-8 Existing Vegetation Classification & Mapping Technical Guide

2.2.3 Vegetation Classification Criteria

Developing a classification system involves selecting criteria for defining and differentiating categories. The criteria used depend on the purpose of the classification. Another

consideration in selecting classification criteria is the number of attributes used to assign

an object to a group. A single factor, a few factors, or many factors may be used to

classify objects. Top-down classifications are usually based on few attributes; bottom-up

classifications typically incorporate many attributes. Vegetation classification systems

have generally used two types of criteria—physiognomic and floristic. 

2.2.3.1 Physiognomic Criteria

Physiognomic classifications subdivide vegetation into categories based on gross differences in life form and vegetation structure. They are usually developed with a top-down

approach and work best at broad scales. Physiognomic classifications typically have few

factors and require relatively little data; however, physiognomic categories are inherently

broad. Examples include terms such as forest, shrubland, and meadow.

Physiognomy is the overall appearance of a kind of vegetation (Daubenmire 1968,

Barbour et al. 1980). Physiognomy is the expression of the life forms of the dominant

plants and vegetation structure (Mueller-Dombois and Ellenberg 1974, Barbour et al.

1980). Life form includes gross morphology (size, woodiness), leaf morphology, life

span, and phenological (or life cycle) phenomena (Barbour et al. 1980). Structure is

“the spatial arrangement of the components of vegetation” (Lincoln et al. 1998).

Structure is a function of plant size and height, vertical stratification into layers, and

horizontal spacing of plants (Mueller-Dombois and Ellenberg 1974). Physiognomy refers

Table 2.1. Two approaches to hierarchical classification.

Divisive approach

(top-down)

Subdivides a group of objects to create types.

Focuses on differences.

Generally uses one or few classification criteria.

Usually requires little observation of objects.

Usually based on a simple dataset.

Best suited for large sets of objects.

Works best over large areas; is less useful for 

small areas.

Upper level units are usually more clearly defined 

than lower level units.

Often used to express and clarify known 

relationships and patterns.

Resulting classification tends to be conceptual and 

a priori.

Agglomerative approach

(bottom-up)

Groups individual objects together to create types.

Focuses on similarities.

Often uses many classification criteria.

Often requires detailed observation of the objects.

Usually based on a complex dataset.

Best suited for small sets of objects.

Works best in small areas; often breaks down for 

large areas.

Lower level units are usually more clearly defined 

than upper level units.

Usually used to detect unknown relationships and 

patterns, or to quantify known relationships.

Resulting classification tends to be empirical and 

a posteriori.
Existing Vegetation Classification & Mapping Technical Guide 2-9

to the general appearance of the vegetation; structure describes the spatial arrangement

of plants in more detail. “Physiognomy should not be confused with structure”

(Mueller-Dombois and Ellenberg 1974). 

2.2.3.2 Floristic Criteria

Floristic classifications emphasize the plant species comprising the vegetation instead

of life forms or structure. Floristic classifications are based on community composition

and/or diagnostic species. In practice, most floristic classifications incorporate life form

or vegetation layers to some degree. Floristic classifications can be developed using a

top-down (e.g., dominance types) or bottom-up (e.g., associations) approach, but the latter is more commonly used (see table 2.1). Floristic classifications work better than

physiognomic classifications at finer scales and generally require more data to develop.

Community composition is the kinds, absolute amounts, or relative proportions of

plant species present in a given area or stand. Community composition can be described

qualitatively or quantitatively. The latter may use either absolute amounts or relative

proportions of the plant taxa present. Express the amount of each plant taxon as percent

cover (FGDC 1997, Jennings et al. 2004). Differentiate these three approaches using the

following terms:

• Floristic composition is “a list of the plant species of a given area, habitat, or association”

(Lincoln et al. 1998). It provides a qualitative description of a plant community. 

• Absolute composition is a list of the absolute amounts of each plant species present in

a given area or stand. Express the amount of each plant taxon as absolute percent cover.

• Relative composition is a list of the proportions of each plant species relative to the

total amount of all species present in a given area or stand. Express the proportion of

each plant taxon as relative percent cover.

Floristic composition alone provides less ecological information than a quantitative

description of community composition (Daubenmire 1968, Greig-Smith 1983). Absolute

composition is more informative than relative composition. As Daubenmire (1968) states:

It is more important to know that species A has 12 percent coverage in a stand

than that it provides 75 percent of the total plant cover. Only the absolute values

give an insight into the capacity of the environment to support vegetation.

A list of plant species is included in absolute or relative composition; species amounts or

proportions, however, cannot be derived from floristic composition. Relative composition

can be derived from absolute composition, but not vice versa. Plot data that include

absolute composition provide the greatest flexibility for developing a floristic vegetation

classification. 
2-10 Existing Vegetation Classification & Mapping Technical Guide

Diagnostic species are “any species or group of species whose relative constancy or

abundance can be used to differentiate one [vegetation] type from another” (Jennings et

al. 2004). This definition implies that diagnostic species must be determined empirically

through analysis of plot data (Mueller-Dombois and Ellenberg 1974). Identifying diagnostic species is an inherent part of classifying associations and alliances. Diagnostic

species include dominant, differential, character, and indicator species, defined below:

• Dominant species—“the species with the highest percent of cover, usually in the

uppermost... layer” (Kimmins 1997, as cited in Jennings et al. 2004). Dominant

species represent a quantitative difference in composition between vegetation types.

Two stands or types may have identical floristics but differ in dominant species.

• Differential species—a plant species that because of its greater constancy and/or

abundance in one vegetation type than another, can be used to distinguish the two

types (adapted from Jennings et al. 2004). A differential species serves to distinguish

between two vegetation types.

• Character species—“a species that shows a distinct maximum concentration

(quantitatively and by presence) in a well-definable vegetation type” (Mueller-Dombois

and Ellenberg 1974). A character species shows “a distinctive accumulation of

occurrences in only one [vegetation] type” (Jennings et al. 2004). A character

species distinguishes one vegetation type from several others.

• Indicator species—“a species whose presence, abundance, or vigor is considered

to indicate certain environmental conditions” (Gabriel and Talbot 1984, as cited in

Jennings et al. 2004). Indicator species may represent a qualitative or quantitative

distinction between community types.

Dominant species are generally self-evident. Other diagnostic species are typically

determined empirically through analysis of species abundances and environmental data;

however, they may be selected a priori if their ecology is well understood. Grouping

plots based on species composition usually occurs by using multivariate procedures that

objectively search for groups of species that occur together repeatedly across the landscape. The diagnostic value of a species may change across its geographic range due to

genetic variation, compensating environmental factors, or changes in associated species.

Habitat is not a classification criterion for existing vegetation, but is important for

descriptive and interpretive purposes. Habitat is “the combination of environmental

or site conditions and ecological processes (such as disturbances) that influence the

community” (Jennings et al. 2004). The distributions of diagnostic species along

environmental gradients may be used to evaluate the utility of a classification.
Existing Vegetation Classification & Mapping Technical Guide 2-11

2.2.3.3 Vegetation Cover Concepts

Abundance of plant species can be measured in numerous ways, but the standard measure

for vegetation classification purposes is percent cover. Cover is a meaningful attribute

for nearly all plant life forms, which enables their abundances to be evaluated in comparable terms (Daubenmire 1968, Mueller-Dombois and Ellenberg 1974). Percent cover

can be defined generically as “the vertical projection of the crown or shoot area to the

ground surface expressed as...percent of the reference area” (Mueller-Dombois and

Ellenberg 1974). The use of crown or shoot area results in two definitions of cover:

• Canopy cover is “the percentage of ground covered by a vertical projection of the

outermost perimeter of the natural spread of foliage of plants. Small openings in the

canopy are included” (SRM 1989, USDA NRCS 1997). 

• Foliar cover is “the percentage of ground covered by the vertical projection of the

aerial portion of plants. Small openings in the canopy and intraspecific overlap are

excluded” (SRM 1989). Foliar cover is the vertical projection of shoots, i.e., stems

and leaves.

Foliar cover is usually less than, and never greater than, canopy cover (Daubenmire

1968, SRM 1989). Neither can exceed 100 percent for a single species, but both can total

more than 100 percent for all the species in a plot or stand due to overlap between species

(Daubenmire 1968). Canopy cover or canopy closure for a single life form or layer also

cannot exceed 100 percent. For example, tree canopy closure and total vegetation canopy

cover as described in section 3.222 cannot exceed 100 percent.

Foliar cover and canopy cover are “not necessarily correlated” (Daubenmire 1968)

for either a species or a plant community. All Forest Service vegetation sampling for

classification purposes must use canopy cover, not foliar cover, for the following reasons:

• Canopy cover better estimates the “area that is directly influenced by the individuals

of each species” (Daubenmire 1968).

• Canopy cover, or canopy closure, is easier to estimate from aerial photos than foliar

cover and is more likely to correlate with satellite image analysis. A classification based

on canopy cover is better suited for mapping vegetation than one based on foliar cover.

• The majority of Forest Service legacy data for vegetation classification uses canopy

cover instead of foliar cover.

2.2.4 Association Criteria

An association is “a vegetation classification unit defined on the basis of a characteristic

range of species composition, diagnostic species occurrence, habitat conditions, and

physiognomy” (Jennings et al. 2004). Based on this definition, associations are classified

primarily based on community composition and diagnostic species. Physiognomy and
2-12 Existing Vegetation Classification & Mapping Technical Guide

structure are secondary criteria that are often correlated with floristics because life form

is constant for most species. Although habitat is not a classification criterion for existing

vegetation, habitat information is needed to describe the environmental range of an association. An association with a wide environmental range may be of little interpretive

value for conservation and management. Environmental data are also required to work

out successional relationships among associations and relate existing vegetation to

potential natural vegetation (PNV).

Because diagnostic species are determined empirically through numerical analysis,

vegetation plot data for classification of associations must include a complete species list

with canopy cover estimates for each species. Physiognomic data must also be collected

so that associations can be grouped later into alliances and related to the physiognomic

levels of the NVCS (FGDC 1997, Jennings et al. 2004). The minimum amount of plot

data needed for classifying associations is described in section 2.2.6.1.

2.2.5 Alliance Criteria

An alliance is “a vegetation classification unit containing one or more associations and

defined by a characteristic range of species composition, habitat conditions, physiognomy,

and diagnostic species, typically at least one of which is found in the uppermost or

dominant stratum of the vegetation” (Jennings et al. 2004). Because an alliance is a

grouping of associations (FGDC 1997), plot data must be collected and analyzed and

associations classified before alliances can be defined. Classification of alliances

requires the same vegetation plot data as classification of associations. 

The standard approach to classifying alliances is to aggregate associations from the

bottom up based on plot data. When immediate business needs require alliance-level

information before completing classification of associations, an interim top-down

approach to classifying “alliances” may be needed. 

The FGDC NVCS (1997) states, “The diagnostic species used to determine...the

alliance...are primarily the dominant species.” Provisional alliances, therefore, may be

defined by dominant species in the uppermost layer. The Ecological Society of America

(ESA) Vegetation Classification Panel describes this approach as follows:

Under data-poor conditions, new alliances may be provisionally identified

through quantitative analysis of data on species in the dominant stratum (e.g.

comprehensive tree layer data in forests), combined with information on the habitat or ecology of the plots. Alliance types developed through such incomplete data

fail to meet the highest standards for defining floristic units.... To improve the

confidence in these units, it is necessary to redefine them through analysis of full

floristic information, such as plots that represent all of the associations that may

be included in the alliance (Jennings et al. 2004).
Existing Vegetation Classification & Mapping Technical Guide 2-13

Provisional alliances, as described above, are equivalent to dominance types. A

dominance type is a recurring plant community “defined by the dominance of one or

more species which are usually the most important ones in the uppermost or dominant

layer of the community, but sometimes of a lower layer of higher coverage” (Gabriel

and Talbot 1984, as cited in Jennings et al. 2004). 

Dominance types are most simply defined by the single species with the greatest

amount of canopy cover in the uppermost layer. Dominance types based on multiple

species require more rigorous data analysis. Classification of dominance types requires

canopy cover estimates for the species in the uppermost vegetation layer and the physiognomic attributes of the NVCS (FGDC 1997). These data are relatively easy to

acquire and may be obtained from existing information, such as stand exams or FIA

plots. Observational or anecdotal information can be used to help develop dominance

types, but by itself is inadequate to define differentiating criteria.

Published vegetation types that may serve as provisional alliances include the following:

• Provisional alliances of the International Classification of Ecological Communities

(ICEC), originally published by The Nature Conservancy (Anderson et al. 1998) and

currently maintained by NatureServe (2004).

• Society of American Foresters (SAF) forest cover types based on plurality of basal

area (Eyre 1980). SAF types apply only to stands with 25 percent or more canopy

cover of trees.

• Society for Range Management (SRM) rangeland cover types based on “the present

vegetation that dominates the aspect or physiognomy of an area” (Shiflet 1994).

SRM types apply primarily to nonforested vegetation.

The utility of these published classifications as provisional alliances must be evaluated locally. If none are suitable, a local dominance type classification may be developed.

2.2.6 Classification Standards

Establishment of a new association, alliance, or dominance type requires that the vegetation type be adequately sampled and clearly distinguished from other vegetation types

through written type descriptions and a diagnostic key. Proposed associations and

alliances must be evaluated through peer review and correlation and may then become

established through approval of the regional ecologist or designated vegetation data

steward. Dominance types must be correlated and approved by the regional ecologist or

designated vegetation data steward.
2.2.6.1 Sample Size

This Forest Service protocol requires a minimum of 10 plots to provide a reasonable

description of the range of variation and characteristics of an association, alliance, or

dominance type. Gauch (1982) recommends a minimum of 5 to 10 plots to establish and

characterize a vegetation type. The plots should be well distributed over the geographical

and ecological ranges of the type. Broadly distributed types may require more than 10 plots

to adequately sample their geographical and ecological ranges. Under special conditions

(e.g., difficulty of access), fewer than 10 plots may be used to describe a vegetation type,

but under no conditions should a type be based on less than three samples. The regional

ecologist must approve any exemption from the sample size requirement. These sample

size requirements are based on preferential sampling, as described in section 2.3.2.

2.2.6.2 Diagnostic Keys

A dichotomous key to the vegetation types is required. A dichotomous key is simpler to

use and understand than a key with multiple choices. There should be only two choices

at each decision point so that the user has only to select one or the other. Figure 2.2

presents a simple example of a dichotomous key.

It should be noted that diagnostic keys generally do not exist for the published

dominance types described in section 2.2.5 (ICEC alliances, SAF cover types, and SRM

cover types). Consistent use of these dominance types will require development of

national or regional keys. Such keys will require field-testing and refinement; e.g., see

the key to sagebrush alliances developed by Reid et al. (2002).

Figure 2.2. Dichotomous key example.

Key to Woodland Dominance Types

1a. Quaking aspen (Populus tremuloides) the dominant tree present ................. QUAKING ASPEN D.T.

1b. Not as above ...........................................................................................................................................2

2a. Bigtooth maple (Acer grandidentatum) the dominant tree present........... BIGTOOTH MAPLE D.T.

2b. Not as above ...........................................................................................................................................3

3a. Gambel oak (Quercus gambellii) the dominant tree present ...............................GAMBEL OAK D.T.

3b. Not as above ...........................................................................................................................................4

4a. Curlleaf mountain-mahogany (Cercocarpus ledifolius) the 

dominant tree present..................................................CURLEAF MOUNTAIN-MAHOGANY D.T.

4b. Not as above ...........................................................................................................................................5

5a. Junipers (Juniperus spp.) with or without various pinyon pines (Pinus spp.) the 

dominant tree species present...............................................JUNIPER-PINYON WOODLAND D.T.

5b. Not as above.........................................................................UNIDENTIFIED WOODLAND TYPES

2-14 Existing Vegetation Classification & Mapping Technical Guide
Existing Vegetation Classification & Mapping Technical Guide 2-15

2.2.6.3 Correlation of Vegetation Types

The regional ecologist must correlate associations, alliances, and dominance types. Correlation

requires a manuscript that minimally includes vegetation type descriptions, a diagnostic

key, and descriptions of sampling and analysis methods. In addition to the manuscript, the

following information is required for correlation of association and alliances:

• Synthesis tables (summaries of constancy and mean cover by species for each type).

• Association tables (individual plot data for each type).

• A map showing all plot locations for each vegetation type.

Regional ecologists may require additional information for correlation at their discretion.

2.3 Sampling Strategy

In this section: Stratification of study area and plot location approaches

Random or systematic sampling across a study area is inefficient and costly because

a very dense set of sample points is required to include the variation inherent in the landscape (Mueller-Dombois and Ellenberg 1974, Gauch 1982). The study area should be

stratified to optimize the distribution of samples and reduce the number of samples required. 

2.3.1 Stratification of Study Area

Stratification of the study area may be based on environmental factors, vegetation patterns,

or a combination of both. Environmental factors can be used to stratify the study area in

an objective manner for vegetation classification. Stratification based solely on vegetation

cover is always subjective (Mueller-Dombois and Ellenberg 1974) and can potentially

bias the resulting classification.

Environmental factors useful for stratification include elevation, slope, aspect, climatic

factors, geologic parent materials, soils, and hydrologic conditions. The first three factors

can be generated from digital elevation models (DEMs). Maps of climatic factors created

by the PRISM or Daymet models are available online; for PRISM, visit

http://www.ocs.orst.edu/prism/prism_new.html, and for Daymet, visit

http://www.forestry.umt.edu/ntsg/bioclimatology/daymet/. 

For classification of associations, the use of vegetation cover for stratification

should be limited to obvious physiognomic types and dominance types to minimize

bias. Stratification into finer vegetation units requires detailed knowledge of the study

area based on intensive reconnaissance (Mueller-Dombois and Ellenberg 1974).
2-16 Existing Vegetation Classification & Mapping Technical Guide

2.3.2 Plot Location

Plots may be located in sampling strata either preferentially (Gauch 1982, Jennings et al.

2004) or objectively (Mueller-Dombois and Ellenberg 1974). Preferential sampling locates

plots in areas with relatively uniform physiognomy, floristic composition, and environmental conditions. Objective sampling locates plots systematically or randomly in strata.

The objective approach is also called representative sampling (Jennings et al. 2004).

Preferential sampling should locate plots “subjectively without preconceived bias”

(Mueller-Dombois and Ellenberg 1974). This means that plots are carefully selected for

homogeneity of vegetation and environment, but are not selected because they “fit” a

preconceived community type. Selection of “typical” stands or rejection of “degraded”

or “atypical” stands may introduce bias unnecessarily and lead to erroneous conclusions

(Mueller-Dombois and Ellenberg 1974).

Homogeneity is a matter of subjective judgment because no stand is absolutely

homogenous, and homogeneity is dependent on plot size (Mueller-Dombois and Ellenberg

1974, Gauch 1982). No completely objective way exists to evaluate homogeneity, but

the following guidelines have been successfully used by ecologists for many years

(Mueller-Dombois and Ellenberg 1974, Gauch 1982):

• The plot should not include any obvious change in physiognomy.

• The predominant taxa in each vegetation layer should be consistently distributed

across the plot.

• The plot should not encompass any abrupt changes or obvious gradients in environmental factors, such as slope, aspect, geologic parent materials, or soil depth, moisture,

or texture.

The data to be collected on each plot may place further restrictions on plot location.

For example, if site index is to be measured on each plot, samples cannot be located in

stands that lack suitable site trees. For example, an otherwise acceptable stand may be

rejected for sampling because the trees are infected with mistletoe.

Representative sampling employs systematic or random location of plots in strata,

but rejection criteria may be necessary to avoid sampling obvious ecotones, which are of

limited use for classifying vegetation. The “gradsect” technique, or gradient-directed

sampling, is one example of this approach (Austin and Heylingers 1991, as cited in

Jennings et al. 2004). This technique is a form of stratified random sampling that may

be cost effective for sampling vegetation patterns along environmental gradients

(Gillison and Brewer 1985).

As long as rejection criteria are defined ahead of time, the objectivity of the sampling will be maintained. The rejection criteria listed above for preferential sampling

also apply to representative sampling. Representative sampling should be used when the
Existing Vegetation Classification & Mapping Technical Guide 2-17

stratification units are large and variable or when statistical support for conclusions is

desired (Mueller-Dombois and Ellenberg 1974), which may accommodate additional

business needs.

2.4 Sampling Methods

In this section: Plot size and shape, life forms and layers, species data requirements,

canopy cover estimation, environmental data, metadata, and FGDC physiognomic

requirements

The ocular macroplot, or relevé (Mueller-Dombois and Ellenberg 1974, Jennings

et al. 2004), sampling method is the fastest and most efficient sampling approach for

vegetation classification. 

The ocular macroplot procedure consists of the following steps:

1. Mark the plot boundaries.

2. Record environmental attributes. 

3. Record plot location, preferably by global positioning system (GPS) and metadata.

4. List all the plant species present in the plot.

5. Estimate canopy cover for each species by layer (also height and diameter class

if desired).

6. Estimate canopy cover, height, and diameter class of required life forms and layers.

7. Obtain required FGDC physiognomic field plot data.

Photographs of the plot and its landscape setting are strongly recommended.

Appendix 2A provides instructions and example field forms for the ocular macroplot

vegetation sampling method.

The cover-frequency (USDA Forest Service 2002b) and line intercept (USDA Forest

Service 2002d) methods are useful for calibrating ocular cover estimates. They produce data

generally suitable for floristic classification, but require much more time and effort than the

ocular macroplot method. Both methods miss many species when compared with macroplot

sampling (Jennings et al. 2004). The cover-frequency and line intercept methods are not

compliant with the FGDC NVCS because they do not accommodate all the physiognomic

attributes required to crosswalk data to the NVCS physiognomic hierarchy 

2.4.1 Plot Size and Shape

Plots should be small enough to be efficient, yet large enough to include most of the

species present in the community. Presampling tests should be conducted by listing the

species present in a set of nested plots of increasing area. The required minimum plot size
2-18 Existing Vegetation Classification & Mapping Technical Guide

can then be determined from a species area curve, i.e., by plotting number of species

against plot size. A plot meets the minimal area requirements when enlarging the plot adds

no or very few new species. Plots larger than the minimal area provide acceptable data but

are less efficient in terms of the time required to sample the plot. If plots are too small,

floristic data will not be adequate for developing a vegetation classification.

Minimal area, as defined above, varies widely by general vegetation type (MuellerDombois and Ellenberg 1974, Barbour et al. 1980, Gauch 1982). Table 2.2 shows several

common plot sizes and the temperate vegetation types in which they are commonly used.

The smallest of these sizes that meets the minimal area criterion generally should be

used for a classification project. One of these sizes should be used unless minimum area

determination indicates a larger plot is needed or the vegetation being sampled occurs in

patches smaller than these sizes.

Adjusting the plot shape to fit in the homogeneous area to be sampled is acceptable.

Staying in a homogeneous area is more important for classification work than the shape

of the plot. The plot shape (square, rectangular, or circular) is up to the user, but the

entire plot should fit in the vegetation stand. Plot size should not be adjusted on steep

Table 2.2. Commonly used macroplot sizes.

Plot dimensions Default plot Temperate vegetation

Standard Equivalent Radius of Side of dimensions or types where

plot area plot area circular plot square plot shape commonly used

50 m2 ~1/80 ac 4.0 m 7.1 m 5 x 10 m Riparian shrubland

13.1 ft 23.2 ft rectangular Riparian herbland

Alpine vegetation 100 m2 ~1/40 ac 5.6 m 10.0 m 10 x 10 m square Grassland 18.5 ft 32.8 ft

375 m2 ~1/11 ac 10.9 m 19.4 m circular Low-diversity forest

(legacy only) 35.9 ft 63.5 ft Shrubland 

Grassland 400 m2 ~1/10 ac 11.3 m 20.0 m 20 x 20 m square Riparian forest and woodland 37.0 ft 65.6 ft Riparian large shrubland

1/10 ac ~405 m2 11.4 m 20.1 m circular

37.2 ft 66.0 ft

500 m2 ~1/8 ac 12.6 m 22.3 m circular

41.4 ft 73.3 ft

800 m2 ~1/5 ac 16.0 m 28.3 m 20 x 40 m Forests with widely 

52.4 ft 92.7 ft rectangular spaced large trees

1/5 ac ~810 m2 16.1 m 28.4 m

52.7 ft 93.3 ft circular

1000 m2 ~1/4 ac 17.8 m 31.6 m 20 x 50 m High-diversity forests

58.5 ft 103.7 ft rectangular

2500 m2 ~3/5 ac 28.2 m 50.0 m 50 x 50 m square Old growth forests with very

92.5 ft 164.0 ft large trees
Existing Vegetation Classification & Mapping Technical Guide 2-19

slopes to avoid overestimating canopy cover as compared to plots on level ground

(Mueller-Dombois and Ellenberg 1974). For instructions for recording plot area and

dimensions, see appendix 2A.

2.4.2 Identification of Life Forms and Layers

Canopy cover of major life forms is required to describe vegetation structure, to crosswalk plot data and vegetation types to the FGDC physiognomic hierarchy (FGDC 1997,

Jennings et al. 2004), and to meet additional Forest Service business needs. Life forms

required for Forest Service business needs are described below. Addition life forms

required for FGDC compliance are described in section 2.4.9.1.

2.4.2.1 Required Life Forms

Percent canopy cover must be estimated for each of the following life forms. Percent

canopy cover of any life form is the percentage of the plot area included in the vertical

projection of the outermost perimeter of the natural spread of foliage of plants of that life

form (section 2.2.3.3). Canopy cover of any single life form cannot exceed 100 percent.

Trees

Woody plants that generally have a single main stem and have more or less definite crowns.

In instances where life form cannot be determined, woody plants at least 5 meters in height

at maturity will be considered trees (adapted from FGDC 1997). 

Shrubs

Woody plants that generally exhibit several erect, spreading, or prostrate stems which

give it a bushy appearance. In instances where life form cannot be determined, woody

plant less than 5 meters in height at maturity will be considered shrubs (adapted from

FGDC 1997).

Dwarf-shrubs—Caespitose, suffrutescent, creeping, matted, or cushion-forming

shrubs that are typically less than 50 cm tall at maturity due to genetic and/or

environmental constraints (adapted from FGDC 1997). Does not include shrubs

less than 50 cm tall due to young age or disturbance.

Herbs

“Vascular plants without significant woody tissue above the ground...with perennating

buds borne at or below the ground surface” (FGDC 1997). Includes graminoids, forbs,

ferns, club mosses, horsetails, and quillworts.

Graminoids—Nonaquatic flowering herbs with relatively long, narrow leaves and

inconspicuous flowers with parts reduced to bracts. Includes grasses, sedges, rushes,

and arrowgrasses (adapted from FGDC 1997).
2-20 Existing Vegetation Classification & Mapping Technical Guide

Forbs—Nonaquatic, nongraminoid herbs with relatively broad leaves and/or showy

flowers (adapted from FGDC 1997). Includes both flowering and spore-bearing,

nongraminoid herbs.

Appendix 2A, section 2A.2.2 includes instructions for recording canopy cover by

life form on the Vegetation Composition field form.

2.4.2.2 Required and Optional Tree Layers

For trees, canopy cover, predominant tree height, predominant crown height, and predominant diameter by layer are used to describe vegetation structure to provide a rough

picture of past stand dynamics, and to crosswalk to the FGDC physiognomic hierarchy.

For detailed instructions on recording these attributes on the Vegetation Composition

form, see appendix 2A, section 2A.2.4.2. Percent canopy cover, predominant tree height,

predominant crown height, and predominant diameter (section 2.4.2.3, below) must be

estimated for the tree overstory and regeneration layers. Recognition of these layers is

dependent on the potential height growth of the tree species making up the stand. For

this purpose, dwarf trees are defined as trees that are typically less than 12 meters tall

at maturity due to genetic and/or environmental constraints. Examples include pinyon

pines, junipers, and mountain mahogany.

Overstory (TO)

Trees at least 5 meters in height that make up the forest canopy or dwarf trees that have

attained at least half of their (site-specific) potential height growth and make up the forest canopy.

Regeneration (TR)

Trees less than 5 meters in height or dwarf trees that have attained less than half of their

(site-specific) potential height growth and are clearly overtopped by the overstory layer.

The overstory layer may optionally be subdivided into the following sublayers to

describe vegetation structure in more detail: 

• Supercanopy (TOSP)—Scattered overstory trees that clearly rise above the 

main canopy.

• Main Canopy (TOMC)—Dominant and codominant overstory trees that receive

direct sunlight from above.

• Subcanopy (TOSB)—Overstory trees clearly overtopped by, and separate from, the

main canopy, but taller than the regeneration layer.
Existing Vegetation Classification & Mapping Technical Guide 2-21

Use these divisions to mentally subdivide the overstory. All sublayers may not be

present. Record percent canopy cover, the predominant or prevailing tree height, predominant

crown height, and the predominant diameter of each sublayer. For example, a stand may

have a main canopy of dominant/codominant trees mostly 20 meters tall and a subcanopy

of younger trees predominately 8 meters tall.

The tree regeneration layer may optionally be divided into the following sublayers:

• Saplings (TRSA)—Regenerating trees less than 5 meters in height but taller than

1.4 meters (4.5 feet) or regenerating dwarf trees taller than 1 meter (3.3 feet).

• Seedlings (TRSE)—Regenerating trees less than 1.4 meters (4.5 feet) in height or

regenerating dwarf trees less than 1 meter (3.3 feet) tall.

Some studies may choose to subdivide seedlings into established and nonestablished

classes. The criteria for established seedlings may vary by species and region. Required

and optional tree and shrub layers are summarized in table 2.3.

2.4.2.3 Optional Shrub Layers

Total percent canopy cover, predominant shrub height, and crown height may optionally

be estimated for the following shrub layers:

• Tall Shrubs (ST)—Shrubs greater than 2 meters in height. (Includes shrubs more

than 5 meters in height but clearly multistemmed.)

• Medium Shrubs (SM)—Shrubs 0.5 to 2 meters in height.

• Low Shrubs (SL)—Shrubs less than 0.5 meter in height.

The low shrub layer includes FGDC’s dwarf shrub life form in addition to shrubs that

are less than 0.5 meter tall due to young age or disturbance. Tall and medium shrubs are

subdivisions of FGDC’s shrub life form. For more information, see section 2.4.9.1.

Table 2.3. Summary of tree and shrub layers.

Life form Required layers Optional sublayers

Trees (T) Overstory (TO) Supercanopy (TOSP) 

Main canopy (TOMC) 

Subcanopy (TOSB) 

Regeneration (TR) Sapling (TRSA) 

Seedling (TRSE) 

Established (TRSEE) 

Nonestablished (TRSEN) 

Shrubs (S) Tall shrubs (ST)

Medium shrubs (SM)

Low shrubs (SL)
2-22 Existing Vegetation Classification & Mapping Technical Guide

2.4.3 Species Identification

A list of all vascular plant species identifiable at the time of sampling is required on all

vegetation classification plots. Identification of vascular plants to the subspecies or variety

level may be required for some projects. Include plants if their crowns overhang the plot

area, even though their root systems may not be in the plot area, except when sampling

narrow riparian communities. In such riparian communities, do not include overhanging

trees rooted outside the community (across an ecotone) in the species list.

Floristic classification requires accurate plant identification. Correct species identification is more important than accuracy in cover estimates. Overlooking or misidentifying

a species is a more serious error than estimating cover as 5 percent when a measurement

would show it to be 3 percent. Field employees must be well qualified and/or trained in

species identification, use of accepted scientific floras, and proper collection of

unknown species for later identification.

Botanical nomenclature should follow a standard flora for the geographic area being

sampled. The floras used should be identified in any products (e.g., publications, database)

produced by a classification project and included in the project metadata. Codes for

plant species must follow the PLANTS database (USDA NRCS 2002). 

Any plant that cannot be identified to the species level should be collected for later

identification. Assign a collection number to the specimen and record the number on the

field form along with other required information (e.g., percent cover, life form).

2.4.4 Species Canopy Cover Data

Estimate the total canopy cover of each species using the procedure described in section

2.4.5. For a tree species, estimate its canopy cover in the overstory and regeneration layers

in addition to total cover for the species. Assign each species in the macroplot an appropriate life form and life form modifier as defined in section 2.4.9.1. Each species can

belong to one life form only. 

Estimating canopy cover for each tree species in each optional sublayer is recommended

but not required. Estimating canopy cover provides approximate relative age distributions

for tree species (Daubenmire 1968, Mueller-Dombois and Ellenberg 1974), which can

be used to roughly describe past succession in the stand. Because size-age relationships

are not constant, interpret such data with caution and supplement it with actual age data

(Harper 1977).
Existing Vegetation Classification & Mapping Technical Guide 2-23

2.4.5 Canopy Cover Estimation

Canopy cover is the percentage of the plot surface area covered by the periphery of the

foliage of the plants. Do not use cover classes. Estimate percent canopy cover of each

species, life form, layer, or size class in the plot as follows: 

• Use 0.1 as “trace” for items present but clearly less than 1-percent cover.

• Estimate to the nearest 1 percent between 1- and 10-percent cover.

• Estimate to at least the nearest 5 percent between 10- and 30-percent cover.

• Estimate to at least the nearest 10 percent for values exceeding 30-percent cover.

In the species list, do not record species that do not occur in the plot, but are present

in the stand. Information from outside the plot can be recorded in field notes, but cannot

legitimately be used in data analysis. A consistent plot size is an important assumption

for most community data analysis procedures; using species data from outside the plot

violates this assumption. If sampling is consistently missing ecologically meaningful

species, use a larger plot size.

Table 2.4 lists commonly used plot sizes and the dimensions of squares representing

1 percent and 5 percent of the plot area. Canopy cover can be consistently estimated by

walking through a macroplot and counting the number of 1- or 5-percent units of a

species present in the plot. Canopy cover for life forms, layers, or size classes can be

similarly estimated. Crosscheck estimates with each other for consistency and to help

account for overlap between layers in a life form or species, species in a layer, and so

forth. It may be helpful to complete cover estimates for each species and the items in

table 2.3 before estimating cover for the required FGDC life forms in section 2.4.9.1.

Data collection personnel must calibrate their estimates of cover. Ocular estimate

calibration should be conducted at the beginning of inventory projects and periodically

throughout the life of the project. Field data collection personnel may calibrate their

Table 2.4. Plot sizes and dimensions of squares equaling 1- and 5-percent of the plot.

Plot size (area) Side of a 1-percent square Side of a 5-percent square

50 m2 0.7 m 1.6 m

2.3 ft 5.2 ft

100 m2 1.0 m 2.2 m

3.3 ft 7.3 ft

400 m2 2.0 m 4.5 m

6.6 ft 14.7 ft

0.01 acre 2.0 m 4.5 m

6.6 ft 14.7 ft

0.2 acre 2.8 m 6.4 m

9.3 ft 20.9 ft

1,000 m2 3.2 m 7.1 m

10.4 ft 23.2 ft
2-24 Existing Vegetation Classification & Mapping Technical Guide

ocular estimates by periodically sampling with cover-frequency transects or line intercept

methods (USDA Forest Service 2002b and 2002d). When using the line intercept method

for calibration, measure canopy cover, not foliar cover (Daubenmire 1968). Quick

comparison of cover estimates can be made by having personnel independently estimate

cover for a few species in a plot and comparing their results. If necessary, the process

may be repeated until all personnel produce similar results.

2.4.6 Plant Height and Diameter Data

Record the predominant plant height and crown height, including unit of measure, for

any tree or shrub layer present in the macroplot. Crown height for trees is the vertical

distance from ground level to the lowest whorl with live branches in at least three of

four quadrants around the stem. Crown height for shrubs is the vertical distance from

ground level to the lowest live foliage or branches. The minimum and maximum height

of each layer are optional attributes. Predominant height is optional for the other life forms

in section 2.4.2.1. Predominant height for each species in each layer is also useful, but

optional, information. For instructions on determining predominant plant height and

crown for trees and shrubs, see appendix 2A, sections 2A.2.4.2 and 2A.2.4.3.

The predominant diameter at breast height (d.b.h.) or root collar (d.r.c.) must be recorded

for each tree layer. Record the diameter to the nearest inch rather than using diameter

classes; classes can be assigned later. For instructions for measuring predominant diameter

and recording it on the Vegetation Composition form, see appendix 2A, section 2A.2.4.2.

2.4.7 Environmental Attribute Data

Plot data used to classify existing vegetation must include floristic composition and

structural attributes. Supplemental data describing abiotic characteristics and disturbance

processes must be collected to understand landscape vegetation patterns, relationships

among plant communities, and successional dynamics and pathways. Such data are also

necessary if the vegetation classification is to be used to evaluate ecological status and

resource conditions.

The minimum required environmental attributes for floristic classification of existing

vegetation are elevation, slope gradient (percent), slope aspect (in degrees azimuth), and

ground cover. In riparian vegetation, the fluvial geomorphic surface should also be

described. Recommended additional information includes landform, slope position, slope

shape, and geologic parent material. Appendix 2A provides guidelines for describing

elevation, slope gradient and aspect, ground cover, slope position, and slope shape.

Guidelines for describing landform and geologic parent material can be found in the

Terrestrial Ecological Unit Inventory Technical Guide (Winthers et al. 2004).

Although not collected in the field, attach climatic data to plot records for data

analysis and description of vegetation types; use national climate coverages such as

DayMet and PRISM or local weather station data.
Existing Vegetation Classification & Mapping Technical Guide 2-25

2.4.8 Metadata

The term metadata refers to “data about the data.” Metadata include information

about how the data were collected and the original intended use of the data. Metadata

are necessary to support proper analysis and application of the data. Ecologists should

review metadata for reliability and applicability before using data from other sources.

In the past, this information often was in hard copy form, if written at all, and

difficult to track down when sharing data. A minimum set of electronic metadata must

accompany all plot data and be input for a project before any plot data can be entered

into the Natural Resource Information System (NRIS) database system. This ensures

that basic metadata will always be stored with the dataset and is accessible to all users.

2.4.8.1 Project Metadata

Project metadata describe how a set of data was collected. Examples include the following: 

• Project Name—Assign a specific name and purpose of the data gathering/data

analysis project. Include references to specific floras used to support plant species

identification as well as other references that may have been used, such as existing

classifications, sample design references, and photography or imagery sets.

• Protocol—Documents the protocol followed (e.g., FSH 1909 Existing Vegetation

Classification and Mapping Protocol).

• Methods—Describes the specific method or type of sample used to collect the data.

For example, the ocular macroplot method may be used for collecting vegetation

attribute, and the cover frequency or line-intercept methods may have been used for

ocular cover calibration. A separate method may have been used to collect optional

tree measurement data (e.g., variable radius plot sampling).

• Sample Design—Documents the sample design used for the plots in a specific project.

Sample design attributes include how the sample units were selected and the size of

the plot. Additional attributes to support cover frequency and line intercept methods

include number of transects, length of transects, and number and size of frames

along the transects.

2.4.8.2 Plot Metadata

Metadata attributes that vary from plot to plot are included as fields on the General Site

Form in appendix 2A. These include a unique site ID, project name, date of collection,

examiners, location information, and air photo information. Whenever measurements

are taken (e.g., elevation, height, diameter), the appropriate unit of measure (feet, meter)

must accompany the value and be stored with the data.
2-26 Existing Vegetation Classification & Mapping Technical Guide

Table 2.5. Required FGDC life forms.

Life form code Name and definition

T Tree—A woody plant that generally has a single main stem and a more or less definite 

crown. In instances where life form cannot be determined, woody plants at least 5 m in 

height at maturity will be considered trees (adapted from FGDC 1997).

S Shrub—A woody plant that generally has several erect, spreading, or prostrate stems 

that give it a bushy appearance. In instances where life form cannot be determined, 

woody plants less than 5 m in height at maturity will be considered shrubs (adapted 

from FGDC 1997). Includes dwarf shrubs and woody vines.

H Herb—A vascular plant without perennial aboveground woody stems, with perennating 

buds borne at or below the ground surface (Whitaker 1970, FGDC 1997). Includes 

forbs, graminoids, and herbaceous vines.

N Nonvascular—A plant or plant-like organism without specialized water or fluid 

conductive tissue (xylem and phloem). Includes mosses, liverworts, hornworts, lichens, 

and algae (adapted from FGDC 1997).

E Epiphyte—A vascular plant that grows by germinating and rooting on other plants or 

other perched structures and does not root in the ground (adapted from FGDC 1997).

L Liana—A woody, climbing plant that begins life as terrestrial seedlings but relies on 

external structural support for height growth during some part of its life (Gerwing 

2004), typically exceeding 5 m in height at maturity.

2.4.9 FGDC Physiognomic Crosswalk Attributes

The FGDC NVCS requires that federally funded vegetation classification plot data

include the attributes needed “to classify units down through the physiognomic levels of

[Division, Order,] Class, Subclass, Group, [Subgroup,] and Formation.” The FGDC

physiognomic hierarchy is being revised, however, and the Subgroup and Formation levels are not clearly defined (see appendix 1B). This protocol, therefore, does not require

field collection of attributes needed to classify FGDC Groups, Subgroups, and

Formations at this time. 

Because of the above situation, the FGDC requirements are reduced to the following:

1. Use the key in appendix 1C to key out the plot to FGDC subclass in the field,

and record the subclass on the General Site Data form.

2. Record a life form and life form modifier for each species on the plot using the

lists in tables 2.5 and 2.6, respectively.

Requirement 1 enables plot data to be quickly crosswalked to the division, order,

class, and subclass levels of the FGDC hierarchy. If needed, the group, subgroup, and

formation can usually be determined from individual species cover data.

Requirement 2 allows for rapid summarization of species data by life form. The life

forms and life form modifiers in tables 2.5 and 2.6 are intended to facilitate the assignment

of plots to categories of the pending revision of the FGDC physiognomic hierarchy.

These requirements will be revised on completion of the revised FGDC physiognomic

hierarchy.
Existing Vegetation Classification & Mapping Technical Guide 2-27

Table 2.6. Required FGDC life form modifiers.

Life form Life form

code modifier code Name and definition

TBD Broad-leaved deciduous tree—A tree with leaves that have well-defined leaf blades that are typically 

greater than 645 square mm (1 sq in) in area and seasonally loses all its leaves and becomes temporarily 

bare-stemmed (FGDC 1997).

TBE Broad-leaved evergreen tree—A tree with a branching crown and leaves that have well-defined leaf blades 

that are typically greater than 645 square mm (1 sq in) in area and has green leaves all year round (FGDC 1997).

T TN Needle-leaved tree—A tree with slender, elongated leaves or with small overlapping leaves that usually lie 

flat on the stem (FGDC 1997). Includes scale-leaved as well as needle-leaved trees, and deciduous as well 

as evergreen.

TS Sclerophyllous tree—A tree with relatively small, usually evergreen leaves that are stiff and firm, and 

retain their stiffness even when wilted (FGDC 1997, Whitaker 1970).

TU Succulent tree—A tree or arborescent plant with fleshy stems or leaves with specialized tissue for the 

conservation of water (FGDC 1997). Includes cacti, Joshua trees, euphorbias, and others more than 5 

meters in height at maturity.

SD Dwarf-shrub—A caespitose, suffrutescent, creeping, matted, or cushion-forming shrub that is typically less 

than 50 cm tall at maturity due to genetic and/or environmental constraints (adapted from FGDC 1997). 

Does not include shrubs less than 50 cm tall due to young age.

SBD Broad-leaved deciduous shrub—A shrub that is typically more than 50 cm tall at maturity with leaves that 

have well-defined leaf blades that are typically greater than 645 square mm (1 sq in) in area and seasonally 

loses all its leaves and becomes temporarily bare-stemmed (FGDC 1997).

SBE Broad-leaved evergreen shrub—A shrub with a branching crown that is typically more than 50 cm tall at 

maturity with leaves that have well-defined leaf blades that are typically greater than 645 square mm (1 sq 

in) in area and has green leaves all year round. (FGDC 1997).

S SM Small-leaved shrub—A shrub that is typically more than 50 cm tall at maturity with leaves that have welldefined leaf blades that are typically less than 645 square mm (1 sq in) in area (FGDC 1997). Includes 

evergreen and deciduous shrubs with small leaves.

SN Needle-leaved shrub—A shrub that is typically more than 50 cm tall at maturity with slender, elongated 

leaves or with small overlapping leaves that usually lie flat on the stem (FGDC 1997). Includes scale-leaved 

as well as needle-leaved shrubs, and deciduous as well as evergreen.

SC Sclerophyllous shrub—A shrub with relatively small, usually evergreen leaves that are stiff and firm, and 

retain their stiffness even when wilted (FGDC 1997, Whitaker 1970).

SU Succulent shrub—A shrub or shrub-like plant with fleshy stems or leaves with specialized tissue for the 

conservation of water (FGDC 1997). Includes cacti less than 5 meters in height at maturity.

HA Aquatic herb—A flowering or nonflowering herb structurally adapted to live floating or submerged in an 

aquatic environment. Does not include emergent herbs such as cattails and sedges (FGDC 1997, Jennings 

et al. 2003).

HF Forb—A nonaquatic, nongraminoid herb with relatively broad leaves and/or showy flowers. Includes both 

flowering and spore-bearing, nongraminoid herbs.

H HFF Flowering forb—A forb with relatively broad leaves and showy flowers. Does not include graminoids, 

ferns, or fern-likes.

HFS Spore-bearing forb—A nonflowering, spore-bearing forb. Includes nonaquatic, nonwoody ferns, club

mosses, horsetails, and quillworts.

HG Graminoid—A nonaquatic, flowering herb with relatively long, narrow leaves and inconspicuous flowers 

with parts reduced to bracts. Includes grasses, sedges, rushes, and arrowgrasses.

NB Bryophyte—A nonvascular, nonflowering, photosynthetic plant that bears leaf-like appendages or lobes 

and attaches to substrates by rhizoids. Includes mosses, liverworts, and hornworts (Abercrombie et al. 1966).

N NA Alga—A nonvascular, photosynthetic plant with a simple form ranging from single- or multi-celled to a fil

amentous or ribbon-like thallus with relatively complex internal organization (Abercrombie et al. 1966).

NL Lichen—An organism generally recognized as a single plant that consists of a fungus and an alga or 

cyanobacterium living in symbiotic association (FGDC 1997).
2-28 Existing Vegetation Classification & Mapping Technical Guide

2.5 Data Storage

In this section: Date storage requirements and data cleaning methods

Store project data, plot data, and vegetation type data that are collected or derived as

part of this existing vegetation classification protocol in the Forest Service NRIS database.

Follow formats and procedures for data storage developed in coordination with NRIS.

All required attributes in this protocol will be supported in NRIS and follow national

standards. Support means that data entry and edit forms will be provided that include

lookup lists of standard codes. Applications and reports will be developed that use this

information. All optional attributes recognized in the national protocol will be accommodated in NRIS. Data entry screens and database fields and standard codes will be

available to hold this information. Corporate tools, however, will be driven largely by

corporate or required data. Data collected at a region’s discretion beyond the required and

optional attributes listed in this technical guide may not necessarily be accommodated in

NRIS and may not follow a national standard. Coordinate with regional and national

stewards on such matters.

Label archival materials associated with the classification project, such as maps,

photos, reports, and plot data sheets, with the project name and store them together in an

accessible and protected location.

2.5.1 Data Cleaning

Review data for completeness and obvious errors before entering it in the corporate

database. The NRIS database makes extensive use of data validation techniques against

standard codes, units of measure, value range checks, and required fields that will also

promote consistent data entry and error checking. After data are entered in the NRIS

database, several common methods can be used to check data for additional errors.

Query the species cover data table for a list of species codes and associated scientific

names. By examining this list, the classifier will find errors in species code entry if

names of species not recognized or known to occur in the study area appear on the list.

NRIS tables will not allow the entry of a nonexistent species code.

Query the appropriate table for lists of other pieces of data collected (e.g., plot

slope, tree heights) and examine the lists to find obvious data entry errors that would

not be disallowed by lookup table restrictions. For example, one could enter a plot slope

of 180 percent, but the reviewer may know that no plot in the study could possibly have

a plot slope of 180 percent.

Query the data table containing all the site identifiers against each table containing

data about the site to see if these other tables contain records for all plots sampled.

Typographic errors may occur in individual plots and must be visually checked

against plot card data.
Existing Vegetation Classification & Mapping Technical Guide 2-29

2.6 Data Analysis

In this section: Data analysis concepts and guidelines

The analysis procedures used by community ecologists are designed to detect patterns and relationships in a dataset, filter out noise, and eliminate outliers (Gauch 1982).

An outlier is a sample with low similarity to all other samples in a dataset. Patterns

include repeating coordinated species abundances and groups of samples with similar

species composition. The patterns reflect relationships between plant species or between

species and environmental factors. Noise is noninterpretable variation in species abundances

that obscure patterns and relationships in the dataset. Sources of noise include chance

distribution and establishment of seeds, local disturbances, microsite variation, outliers,

and misidentification of species. 

No particular analysis process or method produces a vegetation classification. The

available techniques simply produce information that an ecologist uses to help define

vegetation types. The results of data analysis must be interpreted in light of knowledge

of the biotic and abiotic factors influencing plant species distributions in the study area.

Integrating all this information is the job of the ecologist and cannot be automated.

Jennings et al. (2004) state, “Various methods are available for identification of

environmental and floristic pattern from matrices of species occurrence in filed plots.

The substantial menu of available analytical methods allows individual researchers to

select those methods that provide the most robust analyses for the available data” (e.g.,

Braun-Blanquet 1932, Mueller-Dombois and Ellenberg 1974, Jongman et al. 1995,

Ludwig and Reynolds 1988, Gauch 1982, Kent and Coker 1992, McCune and Medford

1999, McCune et al. 2002, and Podani 2000). That ecologists understand the concepts

and mathematics of each method to appropriately interpret the analysis results is also

critical (Pielou 1984).

Multivariate analysis techniques examine the behavior of more than one dependent

variable in a set of parameters. In the case of vegetation analysis, species presence and

species cover values may be used to compare and group individual plots. Floristic data

is often complemented by environmental or other abiotic parameters, such as soil texture, elevation, slope, azimuth, and mean annual or seasonal precipitation values. 

Four fundamental approaches are widely used for vegetation analysis: tabular analysis, clustering, gradient analysis, and ordination (Jennings et al. 2004). Tabular analysis

involves the sorting of a matrix of plots and species in an effort to detect recurring

groups of species, identify diagnostic species, and group similar plots together. Such a

table is referred to as an association table. Clustering methods may be divisive—separating the data into progressively narrower groupings through differences between plots,

or agglomerative—deriving clusters of plots that share common features. Both methods
2-30 Existing Vegetation Classification & Mapping Technical Guide

are sometimes used sequentially to assess the adequacy of the associations developed by

the first method. When environmental parameters are included in the dataset, direct

gradient analysis may be applied to examine the groupings or clusters of plots along

environmental gradients. A variety of software packages provide these types of analyses

in various combinations.

Regardless of the analytical methods used, document proposed associations using

synthesis and association tables to facilitate peer review and correlation of vegetation types

(see section 2.2.6.3). A synthesis table displays constancy and mean canopy cover for each

vegetation type. An association table displays individual plot data for each vegetation

type. Both are invaluable for diagnostic key development and peer review. 

Tables 2.7 and 2.8 show examples of synthesis and association tables using data

from big sagebrush plant associations on the Bridger-Teton National Forest (Tart 1996,

Svalberg et al. 1997). To save space, both examples represent only partial tables. Table

2.7 is a synthesis table that summarizes late and mid-seral plots for six plant associations.

It displays diagnostic species and species with high constancy in at least one association,

rather than a complete species list. Table 2.8 is a partial association table for the same

six plant associations. It displays only the diagnostic species for the late seral plots in

each association. A complete association table would display 140 plots and more than

300 plant species. These plant associations were developed using ordination of floristic

data and tabular analysis of both floristic and environmental data (Tart 1996). Plant

codes follow the Natural Resources Conservation Service (NRCS) PLANTS database.

2.7 Reporting

In this section: Naming and description of vegetation types, and vegetation type metadata

2.7.1 Naming Vegetation Types

The purpose of naming the taxonomic units in a classification is to create a unique, 

consistent identifier for the unit. Naming conventions for taxonomic units must include

short name, scientific name, and common name. This approach facilitates communication

and tracking of the types in databases, maps and reports, and among a variety of potential

audiences. Naming approaches must be coordinated at the regional and national levels

(preferably by the regional ecologist) to provide consistency. 

Use a descriptive approach to naming that uses a combination of dominant and

diagnostic species to name the type. “The names of dominant and diagnostic taxa are

the foundation of the association and alliance names” (Jennings et al. 2004). For names

of associations and alliances, include at least one or more species names from the uppermost layer of the type. For alliances, use taxa from lower layers sparingly. Among the
Existing Vegetation Classification & Mapping Technical Guide 2-31

ARTRP4 ARTRP4 ARTRV2 ARTRV2 ARTRS2 ARTRS2

-PUTR2 /FEID /FEID /ELTR7 /ELTR7 /TRSP2

/ELSP3 -ELSP3 -ELSP3

(n=30) (n=60) (n=17) (n=16) (n=6) (n=11)

Species Con Cov Con Cov Con Cov Con Cov Con Cov Con Cov

Diagnostic species

BASA3 67 3 58 3 24 1 6 tr

PUTR2 93 8 67 6

ARTRP4 100 24 100 22 18 2

ELSP3 100 25 88 14 88 7

ARTRV2 3 tr 5 tr 100 26 100 29 17 2 18 1

FEID 40 1 97 17 100 28 100 30 100 31 100 26

POGR9 7 tr 47 tr 81 1 83 2 100 3

ELTR7 3 tr 7 tr 18 tr 88 3 100 4 100 10

GEVI2 8 tr 41 tr 44 tr 50 1 82 4

ARTRS2 100 27 100 24

TRSP2 3 tr 6 tr 33 tr 73 3

CARA6 13 tr 17 tr 73 3

Species with 50 percent constancy in at least one association

POSE 50 1 45 1 35 1 6 tr

PHLO2 57 1 32 tr 41 tr 19 tr

SYOR2 57 tr 47 1 29 tr 13 tr 9 tr

COUMP2 70 tr 63 1 24 tr

CHVI8 63 1 50 tr 29 tr 6 tr

STCO4 87 4 53 2 47 2 6 tr

HEUN 10 tr 17 tr 53 2 13 tr 9 1

ANMI3 37 1 45 1 94 3 81 3 67 3 55 1

ERUM 50 tr 60 2 100 6 94 4 100 3 73 4

STLE4 33 2 18 tr 24 1 50 2 50 1 9 tr

ARCO5 7 tr 40 tr 59 1 63 1 50 1 36 tr

KOMA 17 tr 76 2 63 1 50 1 9 tr

CAOB4 10 tr 12 tr 65 2 63 1 67 2 9 tr

TAOF 13 tr 13 tr 53 tr 38 tr 50 tr 36 tr

GETR 7 tr 53 tr 88 2 83 1 27 1

ACMIL3 8 tr 71 1 75 1 100 1 91 2

SWRA 3 tr 41 tr 75 1 83 1 64 1

DAIN 3 tr 29 tr 69 2 50 1 18 1

PHMU3 17 tr 20 tr 18 tr 56 1 33 tr 9 tr

ANSES 3 tr 7 tr 35 tr 50 tr 83 tr 45 tr

STNEN2 7 tr 20 tr 35 1 44 1 67 1 45 1

HEHO5 6 tr 13 tr 67 1 27 tr

LILE3 2 tr 24 tr 25 tr 50 tr

BRAN 3 tr 3 tr 12 tr 44 tr 50 tr 18 tr

LIFI 17 tr 55 3

Bold text 60-percent constancy

Black text 25–59-percent constancy

Gray Text < 24-percent constancy

Table 2.7. Synthesis table for vegetation classification example
2-32 Existing Vegetation Classification & Mapping Technical Guide

Table 2.8. Association table for vegetation classification example.

Grp Plot No. BASA3 PUTR2 ARTRP ELSP3 FEID ARTRV POGR9 ELTR7 GEVI2 ARTRS TRSP2 CARA6

1 J1810V 6 40 35 0

J1811V 5 7 30 30

J1814B 4 8 10 20 3

J1817B 3 3 10 30 3

BLEL01 7 20 45

H2001V 20 25 40

K2102V 20 20 20 2

2 H1608B 10 8 17 23

G1306V 2 25 22 28 0

F1225B 10 10 30 5 0

F1214B 1 1 20 10 25

G1316B 10 1 17 40 0

G1705B 7 8 11 15 8

H1804B 1 5 17 25 15

I1705V 10 0 30 20 10

I1706V 3 7 17 20 10

I1712V 0 8 27 12 25

I1720B 4 6 18 20 5

I1723B 5 2 10 0 40

K1901V 1 10 35 30 15

I1902V 30 45 19 12

I1711B 30 7 35 0

3 E0704B 5 15 20 25 0

F1001V 1 15 35 24 1

F1220B 15 35 20

E0915B 20 15 35 0

E0507B 0 50 30 0 0

F1202V 40 35

4 E0509B 45 25

R2805N 20 20 1 15

F1002B 40 30 1 3 1

F1204B 40 35 1 0 0

F0202V 40 30 0 0 0

E0703B 40 35 0 4 0 0

5 D0422B 40 1 10 37

D0218B 30 0 5 45 0

D0436N 25 4 5 2 12

6 B0608B 30 10 1 10 2 15 2 2

D0804B 30 5 2 20 25 25 2 2

D0605B 40 0 15 0 11 4 2

D0607V 35 2 6 4 29

Q2706V 10 1 25 30 5

Group Association short name Association long name

1 ARTRP4-PUTR2/ELSP3 Artemisia tridentata var. pauciflora—Purshia tridentata/Elymus spicatus

2 ARTRP4/FEID-ELSP3 Artemisia tridentata var. pauciflora/Festuca idahoensis—Elymus spicatus

3 ARTRV2/FEID-ELSP3 Artemisia tridentata var. vaseyana/Festuca idahoensis—Elymus spicatus

4 ARTRV2/ELTR7 Artemisia tridentata var. vaseyana/Elymus trachycaulus

5 ARTRS2/ELTR7 Artemisia tridentata ssp. spiciformis/Elymus trachycaulus

6 ARTRS2/TRSP2 Artemisia tridentata ssp. spiciformis/Trisetum spicatum
Existing Vegetation Classification & Mapping Technical Guide 2-33

taxa chosen to name the type, those of the same life form (tree, shrub, herb, or nonvascular) are separated by a hyphen (-); those of differing life forms are separated by a

slash (/). Taxa occurring in the uppermost layer are listed first, followed successively by

those in lower layers. Within the same life form, the order of names generally reflects

decreasing levels of dominance, constancy, or diagnostic value of the taxa. Ensure that

plant codes (i.e., plant symbols) for vascular plant taxa used in type names follow the

USDA-NRCS PLANTS database. Table 2.9 provides several naming conventions examples.

2.7.2 Vegetation Type Descriptions

A necessary product of the vegetation classification process is a standardized taxonomic

description of the alliance, association, or dominance type. A taxonomic description

defines the floristic boundaries of the vegetation type and describes the characteristics

that distinguish it from other vegetation types. A taxonomic description includes the following elements:

• Type Concept. A description of the distinguishing characteristics of the vegetation

type. This should include the diagnostic species that distinguish the type from others

and a general description of physiognomy including major life forms and layers.

• Geographic Distribution. A description should include the geographic distribution

of the vegetation type by State or national forest.

• Vegetation Data. Plant taxa used in describing a vegetation type should be referred

to by a binomial Latin name as well as a common name. Provide a table of plant

taxa, with constancy (percent of plots in which a given species or subspecies occurs),

average percent canopy cover, and range of percent cover of each taxon included in

the type. Clearly indicate diagnostic species in the constancy/cover table. Specify

the main life forms in each type, including height and percent cover of each life

form or layer, as applicable. The sample size for the type must also be included. 

Table 2.9. Examples of vegetation type names.

Short name Scientific name Common name

ABGR/LIBO2 Abies grandis/Linnaea borealis Grand fir/twinflower

TSHE-ABGR/CLUN Tsuga heterophylla-Abies Western hemlock-Grand fir/queencup

grandis/Clintonia uniflora beadlily

ARTRP4/FEID-ELSP3 Artemisia tridentata var. Mountain big sagebrush/Idaho

pauciflora/Festuca idahoensis- fescue-bluebunch wheatgrass

Elymus spicatus
2-34 Existing Vegetation Classification & Mapping Technical Guide

• Environmental Data. Provide information on site conditions, such as climate,

elevation, slope aspects, slope steepness, topographic slope position, landforms,

geologic parent materials, and soils. Describe the range and the central tendency

of these attributes.

• Vegetation Dynamics. A description should include the successional and disturbance

factors that influence the type. Note its successional relationship to other types, if

known.

• Management Interpretations. Descriptive information relevant to management

options and limitations, such as timber productivity, wildlife habitat values, forage

productivity, species diversity, and structural diversity.

• Hierarchy. State the placement of the association, alliance, or dominance type in

the FGDC physiognomic hierarchy from division through group.

• Supporting Data. Specify plot data used in the analysis of the type, including the

number of plots used and the method of analysis used for determining the vegetation

type.

• Comparison to Other Types. Describe how the vegetation type compares to other

similar described types. Include references for those types.

2.7.3 Vegetation Type Metadata

Data that support the description of specific vegetation types (i.e., alliances and

associations) can be stored directly in the corporate database. Examples include the type

name, any coding convention, publication reference, examiners, supporting plot list,

type concept, and summary data, such as species cover and constancy.

Certain classification systems that are national in scope are distributed with the

corporate NRIS database to support plot, polygon, or map unit data where needed. All

vegetation types from the following three existing vegetation classification systems are

distributed and managed nationally in the NRIS database:

• All levels of the FGDC physiognomic classification.

• Society of American Foresters Cover Types.

• Society of Rangeland Management Cover Types.
Existing Vegetation Classification & Mapping Technical Guide 3-1

Section 3. Existing Vegetation Mapping Protocol

3.1 Purpose

The purpose of the protocol that this technical guide describes is to define specific data

standards and provide guidelines for a mapping methodology associated with four map

levels. The four levels are intended to meet a full range of business requirements from

national to subforest geographic extents.

3.1.1 Background and Specific Objectives

Consistent map products currently exist in widely scattered locations across the agency

and were developed in the absence of national standards. The objective of this technical

guide is to provide direction for the development of consistent and continuous existing

vegetation map products at the four hierarchical levels. Successful implementation of

these standards and guidelines will allow appending of existing vegetation maps at the

appropriate level and facilitate consistent and comparable analyses in and across forests,

Regions, and the Nation. Additionally, consistent vegetation maps at ecologically based

extents (e.g., ecological sections) are important to serve the forest, multiforest, regional,

and national business requirements.

The protocol contained in this technical guide identifies data standards and provides

guidelines for map project planning, design, development, and assessment; field and aerial

photography data; and metadata/documentation. The intent of this protocol is not to be

directly prescriptive regarding methods for project planning and product development;

however, numerous specific methodological considerations are provided as references

for the planning and implementation of the mapping process. To determine the most

cost-effective and appropriate means for meeting existing vegetation information needs

is the role of program and project managers. At the beginning of each primary subsection,

a bulleted synopsis summarizes the included content.

3.1.2 Business Requirements

In this section: The relationship of significant business functions to map levels

Business requirements are the basis for identifying the fundamental data elements

of the map unit design process. These business requirements are determined through an

information needs assessment. Localized Forest Service and cooperators’ business

requirements may be factored into the definition of standard data elements, as well as

additional data elements in existing vegetation map products.
3-2 Existing Vegetation Classification & Mapping Technical Guide

Table 3.1 identifies a number of business functions common across the Forest Service.

The standard map units and map features identified in this section of the technical guide

are shared among these business functions. In addition to the standard map units defined

in this guide, specific business functions can drive the definition of regional or local

standards. Additional local standards may include greater thematic detail, supplemental

data elements, or finer spatial resolution. As part of a mapping project plan, carefully

consider the map level most likely to provide the required information. Mapping additional

elements will require additional resources. 

In table 3.1, a number of Forest Service business requirements are related to the map

levels typically required to support those functions. Many of those functions occur at several

Forest Service organizational levels and are often supported by different map products.

The map product levels defined in section 1.3.2.2—national, broad, mid, and base—are

intended to support the basic information needs that exist throughout the Forest Service

and define a relationship between the map products that support those needs.

3.1.3 Products

In this section:

• Map product format and content • Desirable byproducts of mapping

The primary product at each level of mapping will be a geospatial database and

Federal Geographic Data Committee (FGDC)-compliant metadata. The base-level map

product will be a vector format geospatial database; the three remaining levels in the

map hierarchy are optionally raster or vector format. These map products must meet the

specified standards, be geographically continuous in the area of interest, and contain the

data attributes identified in tables 3.3 through 3.7. 

Table 3.1. Existing vegetation map levels supporting Forest Service business.

Map level Representative business requirements

National National strategic inventory

All levels Land management planning

All levels Cooperative program support

All levels Post-fire assessment

Broad, mid Multiforest/bioregional planning

Broad, mid, base Forest risk assessment

Broad, mid, base Rangeland assessment

Broad, mid, base Cumulative effects analysis

Broad, mid, base Viability assessment

Mid, base Forest plan monitoring

Mid, base Forest/regional fuels assessment

Mid, base Ecosystem assessment by watershed

Base Project planning, monitoring, and evaluation
Existing Vegetation Classification & Mapping Technical Guide 3-3

Data sources and deliverable byproducts of a mapping process may include the following: remotely sensed data, including satellite imagery and aerial photography, digital

elevation models (DEMs), interim map products (e.g., image classifications, delineated

polygons), and field reference data.

3.2 Planning, Design, Development, and Assessment

This section elaborates on the project planning and map unit design outlined in section

3.1.1. Map standards will subsequently be defined for the spatial and thematic data

attributes of the four levels of vegetation maps. Individual concepts of map unit design

are detailed in the subsections below.

3.2.1 Project Management

In this section: Steps for planning a mapping project

Project management is the planning, organizing, and managing of resources—

personnel, equipment, time, money, and data—to accomplish a defined objective. 

Successful project management requires a clear definition of project objectives,

identification of all tasks needed to reach the objectives, proper allocation of resources

to accomplish tasks, and constant monitoring of task accomplishments and resource

expenditures.

3.2.1.1 Information Needs Assessment Process

To start an information needs assessment, gathering general information about the

requirements of planned natural resource projects and relate these needs to specific

business requirements for a vegetation map. Information gathering activities may

include the following:

• Identify the project needs:

- Specify the project area (e.g., watershed, forest, ecosection).

- Specify the objectives of the project (e.g., analysis objectives and interpretation 

needs).

- Include the overall project goals and the expected individual products/activities in

the list of objectives.

- Consider the objectives in the context of time, budget, and staff constraints.

• Identify the data requirements:

- Conduct preliminary research to locate and examine applicable existing vegetation 

data and other ancillary data.
3-4 Existing Vegetation Classification & Mapping Technical Guide

- Evaluate existing information for factors such as currency, minimum standards 

compliance, attributes needed to meet project requirements, and correlation or 

relevance to the area of interest.

- Determine the need for developing and/or acquiring new datasets. This may 

include digitizing, purchasing imagery, and other procurement methods.

- Consider issues of scale, resolution, precision, and accuracy of the required data.

- Identify the level and types of vegetation classification to be mapped based on 

analysis objectives and interpretation needs.

• Identify analytical needs:

- Determine the analytical methods to satisfying the project objectives.

- Determine the types of programs, models, or algorithms required for processing 

and analysis. 

3.2.1.2 Identify Resources Needed for Mapping

If the information needs assessment results identify human and information processing

resources as requirements, develop an acquisition plan. The following items are identified

for inhouse mapping. These same factors can be used to develop a government estimate

of costs for outsource contracting for a vegetation map.

• Identify the processing system requirements:

- Consider whether existing hardware and software are appropriate and adequate for 

performing project tasks and producing output products.

- Determine whether the datasets are in the proper format.

- Determine the types of preprocessing, processing, and postprocessing operations 

that must be performed.

- Consider whether the available data storage is adequate for processing and archiving.

• Identify the project’s staffing requirements: 

- Determine the availability of appropriate staff.

- Determine the need to obtain outside expertise (e.g., programmers, remote 

sensing specialists, resource specialists, or statisticians).

- Calculate the time needed to locate outside expertise in the context of project 

budget and schedule.

- Consider training needs of project staff.
Existing Vegetation Classification & Mapping Technical Guide 3-5

3.2.1.3 Vegetation Mapping Project Plan, Schedule, and Budget

Maintain and update the vegetation mapping project plan as a written document throughout

the duration of the project. At a minimum, the project plan should contain these four

elements:

1. The abstract summarizes the project to facilitate communication to interested parties.

2. The technical design clearly and specifically fulfills these requirements:

• State project objectives and identify output products.

• State the methods and data sources to be used.

• Break the workload into identifiable tasks.

• Estimate effort, in hours, and type of personnel and skills by task.

• Estimate resource needs including costs, personnel, and equipment needed by task.

• Identify material and services needed by task.

• Assess risk of failure by task and provide contingency plans for high-risk tasks.

• State the data standards to be followed.

• Include a quality control process and accuracy requirements.

The breakdown of tasks in the technical design is particularly important. Tracking

individual tasks is much easier than trying to manage the whole project as a whole. The

task breakdown is also used to monitor progress and budget. Assessing risks and formulating contingency plans are also important to the technical design. Typical risks for

vegetation mapping projects include the following:

• Problems related to using new or untried technology.

• Probability that primary data for certain geographic areas are not available.

• Probability of delay in acquiring imagery or other data.

• Budget and schedule overruns.

• Problems related to the logistical challenges of fieldwork.

• Training or hiring of skilled personnel.

• Failure to meet specified accuracy standards.

3. The project schedule is constructed from the technical design as follows:

a. Start with the time required for each task as listed in the technical design.

b. Determine which tasks are concurrent and which are sequential.

c. Consider the availability of personnel.

d. Consider constraints related to fieldwork, access to computers, and availability 

of data.

e. Include time for contingency plans.

f. Develop the final schedule.

4. The project budget is calculated by assigning costs to each task identified in the

technical design. Make sure to include salaries, travel and training costs, equipment

and material needs, and required outside services, as well as personnel time.
3-6 Existing Vegetation Classification & Mapping Technical Guide

3.2.2 Map Standards 

In this section:

• Requirements for map unit keys • Definition of standard map attributes 

• Thematic map accuracy requirements • Minimum map feature 

• Spatial map accuracy requirements • Map update cycles

3.2.2.1 Map Unit Keys 

Before developing the map, classification schemes for each map unit standards and any

additional data attributes must be developed. Map keys define mutually exclusive map

units in each classification scheme. Ensure that map units are clearly identifiable

through the mapping process and on the ground. Physiognomic and floristic map keys

must reference the appropriate information source specific to the mapping project (i.e.,

all vegetation associations used to define the desired map units). Map keys must also

contain specific logic for defining and differentiating each physiognomic, floristic, and

structural map unit. 

3.2.2.2 Map Attributes

Existing vegetation maps are based on the areal extent of the map features, the associated

physiognomic and floristic composition attributes, and attributes for structural characteristics. This technical guide identifies vegetation characteristics common to many of the

business needs previously identified. The four attributes described below—physiognomic,

floristic composition, floristic map, and structural characteristic—are standard for the base,

mid, and broad levels. Additional attributes may be necessary to meet local information

needs and will be defined by regional and/or forest program managers. Locally specific

standards will apply across their logical geographic extents to ensure data consistency. 

Physiognomic and Floristic Composition Attributes

Physiognomic and Floristic Composition. Physiognomic and floristic composition are the

fundamental components of a vegetation map. The National Vegetation Classification

Standards (NVCS) (FGDC 1997) defined a hierarchical system for arranging these

components into taxonomic units, which is the foundation for the map hierarchy described

in this technical guide. When the NVCS was adopted as an FGDC standard in 1997, the

standard described the physiognomic and floristic composition components. Two floristic

levels, alliances and associations, were defined. Standards were provided for the physiognomic portion of the hierarchy only. 

To further develop NVCS, the Ecological Society of America (ESA), through a memorandum of understanding with the FGDC, established a vegetation classification panel

(ESA 1999). In May 2002, the ESA vegetation panel submitted Standards for Associations

and Alliances of the U.S. National Vegetation Classification (Jennings et al. 2004). The
Existing Vegetation Classification & Mapping Technical Guide 3-7

ESA document states that “Consistent with FGDC principles, the standards here for

floristic units relate to vegetation classification and are not standards for the identification

of mapping units. Nevertheless, types defined using these standards can be mapped and

can be used to design useful map units subject to the limitations of scale and mapping

technology.” The ESA-proposed standards for associations and alliances, along with the

1997 NVCS physiognomic standards, form the basis for the mapping standards identified

in this technical guide. All map units are assumed to fit somewhere in this classification

hierarchy, regardless of whether they are included in the FGDC classification. 

Landscape features dominated by land uses (e.g., urban areas) and water bodies are

to be mapped as nonvegetative, if they do not meet the minimum standard for vegetative

cover. Mapping continuous areas requires using land use and cover as well as vegetation

classification systems. Although many areas of the national forests could be mapped using

map units defined by vegetation physiognomic classification only, sparsely vegetated

and nonvegetated areas mapped by this classification only provide little information to

the map user. Adding land cover label assignments such as water, barren land, or snow,

would be more informative. Urban and agricultural land use dominated areas will classify,

more often than not, as vegetated condition. Land use can be mapped for vegetative

conditions alone; however, having additional information related to the land use enables

map users to answer questions, such as the amount and location of urban forests or

agricultural vineyards. For an illustration of the intersection between land use/land cover

and physiognomic class and subclass, see appendix 3G.

Each map level requires a minimum degree of compositional detail. The national

level requires the least detail, and the base level the greatest. At a minimum, the most

detailed classification of map units must equal or exceed the least detail required map unit

at the next level higher in the map hierarchy. As an example, table 3.3A lists dominance

type as the most detailed floristic category required for the mid level; the base level requires

more detailed alliances. This ensures that a given map product will aggregate up to the

next level and still meet the required compositional detail at that level. At each level in

the map hierarchy, every category above the lowest required category is also required. 

The FGDC NVCS requires floristic map units based on vegetation types from a fully

documented and adopted existing vegetation classification system. The lack of near term

availability of adopted FGDC vegetation classifications, however, may limit the ability

to develop floristic map units. Additionally, identified business needs may influence the

level of floristic detail defined in the map key. Technological limits and resource constraints

also may preclude the development of the full range of taxonomic units identified to meet

business requirements. In all cases, map units and associated keys must reference the

classification system documents on which they were based. Where an adopted FGDC

existing vegetation classification system is available but map detail is more generalized,

base floristic map units on and reference that classification system. 
3-8 Existing Vegetation Classification & Mapping Technical Guide

Tables 3.3A through 3.4 identify the required (R) or optional (O) hierarchical categories

of physiognomic and floristic composition for each level of map product. Table 3.4 offers

an example of classes for the listed attributes of the hierarchy. The FGDC document

FGDC-STD-005—Vegetation Classification Standard, available at www.fgdc.gov/standards/status, is the source for physiognomic categories. 

Continuous Land Cover Mapping and Land Use Classes. Landscape features dominated

by land uses (e.g., urban areas) and water bodies are mapped as nonvegetated in the

physiognomic hierarchy if they are less than the minimum standard for vegetative cover.

Mapping continuous areas, however, requires using land use and cover as well as vegetation

classification systems. Therefore, land cover and land use classes defined in the Anderson

1 classification system (Anderson et al. 1976) are required for nonvegetated areas.

Although many areas of the national forests could be mapped using map units defined

by vegetation physiognomic classification only, sparsely vegetated and nonvegetated

areas mapped solely as such provide little information to the map user. Land cover

labels such as water, barren land, or snow are more informative and allow for the most

integrated representation of vegetated and nonvegetated landscapes. 

Land use labels in vegetated polygons are not a required component of the mapping

protocol; however, information needs may dictate the codevelopment of land use and

existing vegetation map labels. Urban and agricultural land use dominated areas will

usually classify as a vegetated condition. Although many land uses can be mapped for

their vegetated conditions alone, additional information related to the land use enables

map users to answer questions such as the amount and location of urban forests or agricultural vineyards. For an illustration of the intersection between land use/land cover and

physiognomic class and subclass, see appendix 3G. 

Table 3.2 depicts a simplified relationship between the Anderson 1 land use/land

cover classification system and physiognomic classes.

Physiognomic Classes. Tables 3.3A through 3.3D identify the NVCS physiognomic levels

that are required attributes at each mapping level. 

Floristic Composition. Floristic composition is a fundamental attribute of existing

vegetation maps comprising associations and alliances. Alliances and associations are

classification standards, not map unit standards for the labeling of map features.

Nevertheless, vegetation alliances and associations defined using classification standards

can be used to design map units subject to the limitations of scale and mapping technology

(Jennings et al. 2004).

The association is the most basic unit of vegetation in the NVCS. The NVCS defines

an association as “a recurring plant community with a characteristic range in species
Table 3.2. Relationship between Anderson 1 and FGDC physiognomic class.

Anderson 1 land use land cover

FGDC Urban or Agricultural Range Forest Water Wetland Barren Tundra Perennial

Physiognomic built-up land land land land snow or ice

class land

Closed tree XX X X

canopy—forest

Open tree XX X X

canopy—savannah

Shrubland XX X X X

Dwarf shrubland X X X X

Herbaceous— X XX X X

shrub steppe

Herbaceous X XX X X

grassland

Nonvascular XXX

Sparsely vegetated X X X

Nonvegetated X X X X

Note: Herbaceous—shrub steppe is added as a Forest Service addition to the NVCS.

Table 3.3A. Physiognomic map attributes.

Physiognomic Map level

Classification Category National Broad Mid Base

Physiognomic ordera R R RR

Physiognomic classa

woody vascular plants (tree/shrub) required; R R RR

herbaceous and nonvascular optional

Physiognomic subclassa

woody vascular plants (tree/shrub) required, O R RR

herbaceous and nonvascular optional

a Reflects NVCS physiognomic hierarchy with modifications necessary to meet the Forest Service business requirements (see section

1.5.1.5 for details).

Note: R=required; O=optional.

Table 3.3B. Physiognomic classes—order.

Name Definition

NVCS order—vegetated division

Tree dominated order Areas where tree life form (National Resources Conservation Service [NRCS] plants growth habit has at least 10-

percent cover in the uppermost strata during the peak growing season).

Shrub dominated order Areas where shrub and/or subshrub life forms are at least 10-percent cover in the uppermost strata. 

Herbaceous/nonvascular Areas where herbaceous and/or nonvascular life forms are at least 10-percent cover in the uppermost strata.

dominated order

No dominant life form Areas where vegetation cover is at least 1 percent, but the area does not classify as tree, shrub, or 

order herbaceous/nonvascular dominated.

NVCS Order—nonvegetated division

Nonvegetated order Nonvegetated order usually associated with open water or land use dominated, human-modified land, such as 

heavy industrial, commercial, and transportation facilities.

Existing Vegetation Classification & Mapping Technical Guide 3-9
3-10 Existing Vegetation Classification & Mapping Technical Guide

composition, specific diagnostic species, and a defined range in habitat conditions and

physiognomy or structure” (Jennings et al. 2004). Because the delineation of associations

requires identification of understory species that are not present in the upper canopy,

direct use of associations is appropriate only where the mapping effort includes extensive

ground observations.

The NVCS specifies that floristic alliances are abstract units of vegetation determined

by the floristic characteristics shared among associations and the physiognomic-ecological

characteristics of the higher levels of the classification. Thus, the alliance is defined as a

grouping of associations with a characteristic physiognomy and habitat and that share

one or more diagnostic species that, as a rule, are found in the uppermost or dominant

stratum of the vegetation. 

The development of existing vegetation map units based on NVCS require the availability of alliance descriptions, based on verified associations, developed from appropriate

field plot data as described in section 2 of this technical guide, and is required for baselevel mapping. Because the ESA-proposed standards for associations and alliances have

not been formally adopted as part of the NVC, many years may pass before a comprehensive

Table 3.3C. Physiognomic classes—class.

NVCS class—vegetated (as modified by NFS for minimum life form cover requirements)

Name Definition

Tree dominated order

Closed tree canopy Tree life form dominated land with at least 60-percent canopy crown closure. Tree life form is defined by 

NRCS PLANTS Master growth habit for tree.

Open tree canopy Tree life form dominated land with at least 25-percent but less than 60-percent canopy crown closure. Tree life 

form is defined by NRCS PLANTS Master growth habit for tree.

Sparse tree canopy Tree life form dominated land with at least 10-percent but less than 25-percent canopy crown closure. Tree life 

form is defined by NRCS PLANTS Mastergrowth habit for tree. 

This class is a Forest Service addition to NVCS Order.

Shrub dominated order

Shrubland class Tall shrub life form dominated land with at least 10-percent cover. Less than 10-percent tree cover may be present.

Dwarf shrubland class Subshrub life form dominated land with more than 10- percent cover of subshrubs. Less than 10-percent tree

and/or tall shrub cover may be present.

Herbaceous and nonvascular dominated order

Herbaceous—shrub steppe Herbaceous life form dominated land with at least 10-percent cover, and shrub and/or subshrub life 

class (optional) form of at least 5-percent but less than 10-percent cover. This class is a Forest Service addition to NVCS Order.

Herbaceous—grassland class Herbaceous life form dominated land with at least 10-percent cover. Tree, shrub, and/or subshrub life forms 

must be less than 10-percent cover.

Nonvascular class (optional) Nonvascular life form dominated land with at least 10-percent cover. Tree, shrub, subshrub, and grass life forms 

must be less than 10-percent cover.

No dominant life form order

Sparsely vegetated class Total vegetative cover at least 1 percent but less than 10 percent. Vegetation is scattered or nearly absent; total 

vegetation cover, excluding crustose lichens (which can sometimes have greater than 10-percent cover) is 

generally 1 to 10 percent.
Existing Vegetation Classification & Mapping Technical Guide 3-11

Table 3.3D. Physiognomic classes—subclass.

NVCS subclass—vegetated

Name Definition

Subclass for tree, shrub, and subshrub dominated classes

Evergreen vegetation Evergreen vegetation associations in which evergreen plants generally contribute 75 percent or more to the total 

subclass dominate plant cover. Evergreen species are woody plant species that have green leaves all year round or a plant 

that in xeric habitats has green stems or trunks and never produce leaves.

Deciduous vegetation Deciduous vegetation associations in which deciduous woody plants generally contribute 75 percent or more to 

subclass the total dominate plant cover. Deciduous species are woody plants that seasonally lose all their leaves and 

become temporarily bare-stemmed.

Mixed evergreen-deciduous Tree life form dominated land with at least 10-percent but less than 25-percent canopy crown closure. 

vegetation subclass

Subclass for herbaceous dominated classes

Perennial graminoid subclass Perennial graminoid vegetation associations, graminoids that persist for several years, and species generally 

(optional) contributing to more than 50 percent of the herbaceous vegetation.

Perennial forb subclass Perennial forb vegetation associations, forbs (including ferns and biennials) that persist for several years, and 

(optional) species, generally contributing to more than 50 percent of the herbaceous vegetation.

Annual graminoid and/ Herbaceous life form dominated land with at least 10-percent cover, and shrub and/or subshrub life 

or forb subclass (optional) form of at least 5-percent but less than 10-percent cover. This class is a Forest Service addition to NVCS Order.

Hydromorphic rooted Hydromorphic rooted vegetation of nonemergent graminoids or forbs, structurally support by water, 

vegetation subclass and rooted in substrate (e.g., pond weeds and water lilies).

(optional)

Subclass for nonvascular dominated classes

Bryophyte subclass (optional) Bryophytes (including mosses, hornworts, and liverworts) vegetation generally dominates the nonvascular cover.

Lichen subclass (optional) Lichens (foliose or fruticose) generally dominate the nonvascular cover.

Alga subclass (optional) Algae generally dominate the nonvascular cover.

Subclass for sparsely vegetated classes

Consolidate rock subclass Consolidated rock with sparse vegetation, such as cliffs, outcrops, lava flows, bedrock.

(optional)

Boulder, gravel, cobble, Tallus/scree slopes, rock flats of boulders, cobble, or gravel with sparse vegetation.

or talus subclass (optional)

Unconsolidated material Unconsolidated material (soil, sand, and ash), such as sand dunes, sand flats, sand beaches and shores,

subclass (optional) agriculture field-bare soil, nonagriculture disturbed areas, tidal mud flats 

Urban or built-up subclass Meets Anderson Level 1 land use classification for urban and built-up land but has sparse vegetation. 

(optional) Residential buildings, commercial and industrial complexes, transportation and utilities, paved-over areas. 

Table 3.4. Floristic map attributes.

Floristic Map level

Classification Category National Broad Mid Base

Cover types and type groups (SAF/SRM) OR RR

Dominance types (locally defined) OO RR

Alliancesa OO OR

Associationsa OO OO

a Currently defined levels of the NVCS hierarchy; see section 1.5.1.5 for details.

Note: R=required; O=optional.
3-12 Existing Vegetation Classification & Mapping Technical Guide

set is available across the country to serve as a basis for map unit design. To ensure that

existing vegetation maps meet FGDC standards, use verified and peer-reviewed associations

and derived alliances for the development of map units.

Interim approaches exist for defining existing vegetation map units in the guiding

principles of the NVC. These approaches for mid-level mapping include using provisional associations and alliances maintained in the NatureServe classification database

(NatureServe 2001), with key components available on the NatureServe Web site

(www.natureserve.org/explorer), as well as regionally developed dominance type classification systems. Other acceptable alternatives for broad level mapping include using

cover types including the Society of American Foresters (SAF) forest types (Eyre 1980)

and the Society for Range Management (SRM) cover types (Shiftlet 1994) to develop

the floristic characteristics of map units. 

Dominance types have been widely used in the development of map units where

remote sensing imagery is the primary basis for map feature delineation. As described in

Jennings et al. (2004): 

“Under the dominance approach, vegetation types are classified on the basis of

dominant plant species found in the uppermost stratum. Determining dominance is

relatively easy, requiring only a modest floristic knowledge. However, because

dominant species often have a geographically and ecologically broad range, there

can be substantial floristic and ecologic variation within any one dominance type.”

Dominance types provide a simple method of classification based on the floristic

dominant (or group of closely related dominants) as assessed by some measure of

importance such as biomass, density, height, or leaf area cover (Kimmins 1997). They

represent one of the lowest levels in several published classification hierarchies” (e.g.,

Cowardin et al. 1979, Brown et al. 1980). 

Cover types are typically based on the dominant species in the uppermost stratum of

existing vegetation. Forest cover types developed by the Society of American Foresters (SAF)

are based on the tree species that may by one or more species, having a plurality of basal area

as measured from ground plots” (Eyre 1980). For rangelands, the SRM recently developed

cover types based on the plurality of canopy cover by dominant species (Shiftlet 1994).

In most cases, the map unit descriptions will be parallel to the classification hierarchy

established as stated in the ESA Vegetation panel report (Jennings et al. 2004). In this

guide, these will be referred to as “homogenous type” map units. However, as Jennings

and others (2004) have suggested, “It is important to remember that, while vegetation

varies continuously in time and space, classification partitions that continuum into discrete

units, primarily for practical reasons. ...[Map unit design] approaches, particularly those
Existing Vegetation Classification & Mapping Technical Guide 3-13

that aggregate alliances and associations using vegetation physiognomy as criteria may

be more practical for some uses. For example, in using the NVC alliance class as a target

for vegetation mapping by the Gap Analysis Program (GAP) (Jennings 2000), not all

alliance types can be resolved. In such cases, alliance types are aggregated into map

units of ‘compositional groups’ or ‘ecological complexes’ Although not part of the NVC

standard, such alternative approaches would result in units of vegetation that are just as

‘legitimate.’” Similar situations may arise as the Forest Service attempts to implement

mapping standards based on the NVC. In this technical guide, the term vegetation

complexes is used as analogous to ecological complexes.

• Homogenous types are map units composed of a homogenous condition of vegetation

or uniform type; a map unit composed of a single alliance or dominance type, at

least 85 percent of the area in a polygon. 

• Compositional groups are map units composed of alliances or dominance types

that are spatially discrete but cannot be discriminated into separate map units by

spectral signatures or landscape indices, such as slope, aspect, and elevation. For

example, in the Southern United States compositional groups have been proposed

in the GAP to accommodate mixed vegetation dominated by southern yellow pine. 

• Vegetation complexes are map units distinguished from compositional groups in that

the spatial closeness of the alliances or dominance types prevents discrimination of

separate map features. In North Carolina, for example, pocosin wetlands are spatially

heterogeneous with pond pine woodlands intermixed with several evergreen shrubland

alliances in such close proximity that they cannot be delineated separately yet form

ecologically and spatially repeating patterns across the landscape. 

Mapping units developed from the NVC apply to all existing vegetation regardless of

successional stage or cultural influence. In many areas of the country, forests and other wild

land environments may be intermixed with agricultural lands, recreational developments,

and other developed areas where the vegetated cover meets the standards for mapping existing vegetation. Descriptions of these vegetative cover types are not included or are poorly

represented in the NVC provisional associations and alliances or the SAF cover types. Some

of these cover types may be included in SRM cover type descriptions. In many cases, existing vegetation map units will have to be defined to describe these portions of the landscape.

Map unit descriptions will also need to be developed for areas where the extent of emergent

aquatic vegetation or an exotic plant species is dominant and covers an area in excess of

extent identified for a minimum map feature.

Figure 3.1 shows an example of map units and attributes in a map feature starting at

the top of the hierarchy. 
Structural Characteristic Attributes

Tree Canopy Closure. Tree canopy closure is defined in this technical guide as the total

nonoverlapping tree canopy in a delineated area as viewed from above. (Note that tree

canopy closure is not defined by a hemispherical projection as viewed from below.) Tree

canopy closure less than 10 percent is considered a nontree polygon. Table 3.5 identifies

tree canopy closure breaks that are required for base, mid, and broad level maps. Canopy

closure breaks at 10 percent (base-level) represent feasibly mapped approximations of a

continuous canopy variable and offer the greatest flexibility for user-specified aggregation.

The tree canopy closure breaks are consistent with the physiognomic class breaks for

vegetation. Any additional divisions necessary to meet local requirements must be subdivisions of the categories listed in table 3.5.

Overstory Tree Diameter Map Units. Overstory tree diameter class is defined in this

technical guide as any intervals into which a range of tree diameters may be divided for

classification (Helms 1998). In this protocol, the mean diameter at breast height (d.b.h.)

(4.5 feet, or 1.37 meters, above the ground) is calculated for the trees forming the upper

or uppermost canopy layer (Helms 1998). This mean can be calculated as the Quadratic

Table 3.5. Total tree canopy closure map units.

Canopy closure Map level

categories (%) National Broad Mid Base

0 R

1–9.9 R R R

10–19.9 R

20–29.9 R R

30–39.9 R

40–49.9 O R R R

50–59.9 R

60–69.9 R

70–79.9 R R R

80–89.9 R

90–100 R

Note: R=required; O=optional.

Division: Vegetated

Order: Tree dominated 

Class: Closed tree canopy

Subclass: Evergreen forest

Cover type (SAF): Douglas fir

Dominance type (R5-CALVEG): Douglas fir

Alliance: Douglas fir forest—Bigleaf maple

Association: Douglas fir—Bigleaf maple-hazelnut

Figure 3.1. Map units and attributes in a map feature example.

3-14 Existing Vegetation Classification & Mapping Technical Guide
Existing Vegetation Classification & Mapping Technical Guide 3-15

Table 3.6. Overstory tree diameter map units.

Canopy closure Map level

categories (%) National Broad Mid Base

0–4.9 R R

5–9.9 R R

10–19.9 R R

20–29.9 O O R R

30–39.9 R

40–49.9 R R

50+ R

Note: R=required; O=optional.

Mean Diameter (QMD) or as basal-area-weighted mean diameter. Table 3.6 identifies

tree diameter class breaks that are mandatory for base- and mid-level mapping.

Developing tree size map units at the broad and national levels is optional. Additional

categorical breaks required to meet local requirements in the mid- and base-levels must

aggregate to the standard tree diameter categories. 

3.2.2.3 Thematic Accuracy

Conduct accuracy assessments of the defined map attributes as a standard part of the

mapping process. These assessments should focus on the thematic content of the map

and are not required to determine spatial accuracy of map feature delineations. Apply

the spatial accuracy standards addressed in section 3.2.2.5 primarily to the data sources

used to develop the maps and are not part of a thematic accuracy assessment. 

Accuracy standards are addressed at two levels: (1) minimum accuracy required for

a national corporate vegetation layer, and (2) ideal accuracy goals based on what can

feasibly be obtained. Increased floristic and structural categorical detail and/or increased

mapping difficulty usually result in a higher probability of map error. Realistic accuracy

standards account for the degree of difficulty in mapping due to the nature and detail of

each attribute. For example, physiognomy is less detailed and considered less difficult to

map than the other map attributes and, therefore, has higher accuracy standards associated

with it. Mapping feasibility, however, does not take precedence over the need for accuracy

standards that ensure a useful product. Map attributes, required and optional, that do not

achieve the minimum accuracy standard should populate a national corporate database

structure. The inability to achieve the accuracy standards, however, does not require the

disposal of map products that are the result of significant investment. 

An objective evaluation of map accuracy results will illustrate the nature and magnitude

of map error. A process should then be identified to improve accuracy on substandard

map units. Documentation to alert users of the limited utility that may exist as a result

of low accuracy may also be necessary. A map improvement process will comprise one
3-16 Existing Vegetation Classification & Mapping Technical Guide

or more approaches including remapping and redesign of the map units. Remapping

should logically target the map attributes or map units in question and may require a

change in mapping methodology. Redesigning map units based on mapping feasibility

also provides an opportunity to achieve accuracy standards (see section 3.2.3), typically

through class aggregation. Aggregating classes to map units that are broader than the

standard for the desired map level, however, effectively represents a shift to a coarser

map level. A map product, therefore, may not uniformly meet the accuracy standards for

a given map level. In a hypothetical example, a map meets base-level standards for tree

canopy closure but only achieves floristic accuracy standards for dominance types. In

this case, the map would be considered a mid-level map that exceeds the minimum standard for tree canopy closure. 

To determine map accuracy, several approaches can be taken, some of which are covered in section 3.2.2.3. The assessment methods used should be documented and the results

of all methods reported. The basis for determining compliance with the accuracy standards

will be, by default, a standard error matrix unless otherwise stated in the accuracy assessment documentation. Regional vegetation data stewards will need to determine the adequacy

of a given accuracy assessment method for determining standards compliance.

Table 3.7 lists accuracy goals and standards for the required data attributes at each

map level. Accuracy percentages refer to overall weighted accuracy for each map attribute.

3.2.2.4 Minimum Map Feature

Minimum map feature is the term used to describe the smallest size polygon required in

a map. A homogeneous area must be delineated in a map if this area is equal to or greater

in areal extent than the minimum map feature standard for each map level. Stated another

way, no differing condition, as defined by the map unit design, that is greater in area

than the minimum map feature can be left as an unmapped inclusion in a larger polygon.

Depending on technical feasibility and business need, it may be necessary to map features

smaller in areal extent than the minimum map feature standard.

Table 3.7. Map attribute accuracy goals and requirements.

Vegetation map Map level

attribute National Broad Mid Base

goal standard (%) goal standard (%) goal standard (%) goal standard (%)

Physiognomic order 80–70 90–80 90–80 90–80

Physiognomic class 80–70 90–80 90–80 90–80

Physiognomic subclass 90–80 90–80 90–80

Alliance 80–65 85–65 85–65

Association 80–65 85–65 85–65

Cover type 80–65 85–65 85–65

Dominance type 80–65 85–65 85–65

Tree canopy closure 80–65 85–65 80–65

Tree diameter class 80–65 80–65
Existing Vegetation Classification & Mapping Technical Guide 3-17

Table 3.8 defines the minimum map feature standard for each of the map levels.

3.2.2.5 Georegistration

Each level of the map hierarchy is intended to cover a general analysis scale and/or

business function area. Correspondingly, a measure of spatial precision and accuracy is

implied at each level. Spatial precision is generally determined by the data sources and

methods used to develop a map. Guidelines for appropriate data sources and methods

are outlined in section 3.24. Map scale equivalencies are established for each map level

(i.e., base = 1:24,000, mid = 1:100,000). Obtain the geospatial positioning accuracy of

imagery and ancillary datasets used to derive the existing vegetation maps from the data

provider. The geospatial positioning accuracy of intermediate and final geospatial datasets

produced during the development of an existing vegetation map and any input datasets

will be calculated according to the standard defined in Geospatial Positioning Accuracy

Standards Part 3: National Standard for Spatial Data (FGDC-STD-007.3-1998). 

The National Standard for Spatial Data (NSSDA) is a data usability standard that

defines the process for calculating and reporting the geospatial positioning accuracy of

the data. The data producer is required to determine and report the accuracy of their

datasets according to NSSDA. The NSSDA uses root-mean-square error (RMSE) at the

95-percent confidence level to determine positional accuracy of datasets in ground units.

The accuracy is be tested by comparing the planimetric coordinates of a minimum of 20

well-defined points in the dataset with coordinates of the same points from an independent

source of higher accuracy. If the positional accuracy of a dataset by the prescribed procedure cannot be determined, the NSSDA identifies three alternatives for determining

positional accuracy: deductive estimate, internal evidence, and comparison to source.

Using these alternatives is most appropriate for estimating the positional accuracy of

ancillary datasets from external sources. Do not use these alternatives to determine the

positional accuracy of the primary imagery sets used in producing existing vegetation

maps. Digital orthophotos are generally the best source of control points for assessing

the accuracy of existing vegetation maps. Table 3.9 identifies the horizonal geospatial

positioning accuracy standards for existing vegetation maps (datasets). 

Table 3.8. Minimum map feature standard.

Map level

National Broad Mid Base

Minimum map unit 500 20 5 5

(MMU) (acres)

Table 3.9. Horizontal accuracy requirements.

Map level

National Broad Mid Base

Map scale 1:1,000,000 1:250,000 1:100,000 1:24,000

Horizontal accuracy ± 1666 ft ± 416 ft ± 166 ft ± 40 ft
3-18 Existing Vegetation Classification & Mapping Technical Guide

Table 3.10. Map update frequency.

Map level

National Broad Mid Base

Temporal scale 5–10 years 5–10 years 1–5 years 1–5 years

3.2.2.6 Update Schedule 

Vegetation composition and structure are dynamic; changes in vegetation regularly require

refreshing existing vegetation maps. Each map level has an associated temporal scale that

determines the frequency of map maintenance. In the extent of the time identified, a given

map product will be updated to account for changes in vegetation that have typically

resulted from sudden disturbance, such as fire, insect- and disease-caused mortality, silvicultural treatments, or rapid growth. Gradual successional changes are more difficult

to identify and may need to be accounted for over longer time frames. Section 3.4.3

includes additional information on map maintenance.

Business needs and resource constraints will also play a role in determining the update

cycle. A time range is listed for each map level to allow flexibility in planning map maintenance. Map products with a hierarchical relationship should be on a coordinated schedule

to ensure that updates in the most detailed map are incorporated into upper level maps in

a timely fashion. Table 3.10 lists the temporal scale or update period for each map level.

3.2.2.7 Metadata

FGDC-compliant metadata will accompany map products developed at each level of

the hierarchy. Section 3.4 includes additional information on metadata content and format.

3.2.3 Map Design

In this section:

• Process for designing map units based on physiognomic, floristic, taxonomic units

and structural technical groups

• Determining map feature size and delineation method

Map design involves two fundamental processes. The first process, map unit design,

identifies the vegetation characteristics to be mapped and assembles or develops classification keys for each map attributes used to describe those characteristics. Map unit

design establishes the relationship between vegetation classification and mapping. The

second process, map feature design, identifies the spatial characteristics and structure of

the map. Both processes are implemented to comply with vegetation map standards and

adopted vegetation classifications. Section 3.2.3.3 provides hypothetical examples to

illustrate these process relationships.
Existing Vegetation Classification & Mapping Technical Guide 3-19

3.2.3.1 Map Unit Design

As described in section 1.3.2, the relation of vegetation classification to mapping provides

the basis for map unit design. Classification is the process of grouping of similar entities

into named types or classes based on selected shared characteristics. (Section 1.3 includes

a detailed explanation of the nature of vegetation classification.) Vegetation mapping is

the process of delineating the geographic distribution, extent, and landscape patterns of

vegetation types and/or structural characteristics. Patterns of vegetation types cannot be

recognized until the types have been defined and described. Consequently, consistent

mapping of vegetation types requires that a vegetation classification be developed

beforehand. Any mapping based on vaguely defined types will be inconsistent, hard to

validate, and difficult to compare with other vegetation maps.

The mapping standards for existing vegetation defined in this section include five

types of classifications. The physiognomic and vegetation type classifications are based

on floristic characteristics; the total vegetation canopy cover, tree canopy cover, and tree

size classifications are based on structural characteristics. The physiognomic and vegetation type classification systems consist of associated sets of taxonomic units that are

the basic set of classes or types that comprise the classification systems. Similarly, the

total vegetation canopy cover, tree canopy cover, and tree size classifications consist of

associated sets of technical groups that are the basic sets of classes that comprise the

classification systems. Taxonomic units and technical groups represent a conceptual

description of ranges and/or modal conditions in vegetation characteristics. These taxonomic units and technical groups should provide the basis for vegetation maps that are

consistent with the mapping objectives, appropriate for the map level being produced,

and within the limitations of mapping technology. Establishing the relationship between

these vegetation classifications and map products depicting them is accomplished

through the map unit design process. 

A vegetation map unit is a collection of areas defined and named the same in

terms of their component taxonomic units and/or technical groups (adapted from USDA

Soil Survey Division Staff 1993). These vegetation map units can be based on the taxonomic

units and technical groups of physiognomic, floristic, or structural classifications or

combinations of these. Map units are designed to provide information and interpretations

to support resource management decisions and activities. The map unit design process

establishes the criteria used to aggregate or differentiate vegetation taxonomic units and

technical groups to establish corresponding map units. Therefore, a mapping unit comprises one or more taxonomic units and/or technical groups from one or more specific

classifications. The criteria used to aggregate or differentiate within physiognomic types,

vegetation types, or structural classes to form mapping units depends on the purpose of

and resources devoted to any particular mapping project (Jennings et al. 2003). For example,

map units designed to provide information on existing forest structure to characterize
3-20 Existing Vegetation Classification & Mapping Technical Guide

wildlife habitat or fuel condition would be based on a combination of tree canopy cover

technical groups and overstory tree diameter technical groups. The map unit design

process is more complex for floristic classifications than for relatively simple structural

classifications. The mapping standards for vegetation cover, tree canopy closure, and

tree diameter described in this section represent general purpose map unit designs for

each structural classification at all map levels, although local information needs may

occasionally require exceeding the standards. 

Map units are depicted on maps in individual areas or delineations that are nonoverlapping and geographically unique referred to as map features (e.g., polygon delineations

or region delineations). The map feature delineation process should be based on the map

units identified in the map unit design process. Typically, one map unit is repeated

across the landscape in many individual map feature delineations. 

Map unit design identifies the collection of map features that share a common definition

and label based on their vegetative characteristics (USDA Soil Survey Division Staff 1993).

Each map unit differs, in some respect, from all others in a geographic extent. Map units

are used as map attributes in a geospatial database. Map units are composed of one or more

taxonomic units and/or technical groups that are differentiated in a map unit design process

and characterized in map unit descriptions. Map units generalize all possible vegetation

conditions to the smallest number that meets the intended analysis objectives of the map

and are feasible to produce with available resources and technology. All map units of interest

need to be identified to map vegetation and land cover across the landscape (Gong and

Howarth 1992). Careful planning of the map unit design process is necessary to establish

an adequate foundation for a mapping project (Lachowski et al. 1995).

Table 3.11. Technical group, map unit, and map feature relationship example.

Total vegetation canopy Total vegetation 

cover classification canopy cover mid-level

Canopy cover technical Canopy cover 

groups (%) map units

0 Sparse vegetation

1–9.9

10–19.9 10–29.9-percent canopy cover

20–29.9

30–39.9 30–59.9-percent canopy cover

40–49.9 

50–59.9 

60–69.9 60–79.9-percent canopy cover

70–79.9 

80–89.9 80–100-percent canopy cover

90–100 

Map unit 

design 

process 

converts 

technical map 

units

Map 

feature 

delineation

process

spatially depicts 

map units 
Existing Vegetation Classification & Mapping Technical Guide 3-21

The first logical step in map unit design is to identify taxonomic units and/or technical groups from existing classifications that pertain to each map unit. Classification

keys that may have been developed as part of an existing vegetation classification

should be assembled and used as the foundation for determining floristic map units.

Based on the availability of adopted vegetation classifications and the validity of historical classification systems, using existing classification keys may be useful to map vegetation composition. In the absence of existing classification keys that meet national and

regional standards, new keys will need to be developed.

Map Unit Design Process

When a new map unit design is required to meet local analysis needs that are not met by

the national standard definitions, find a balance of idealized need and resource constraint.

To achieve this balance, take the following steps:

1. Define the user needs. The ideal level of detail and the intended use of the data

must be clearly defined.

2. Identify the resources available. Consider personnel, time, budget, existing data,

and management approval as the critical resources.

3. Identify the source image data to be used. Be aware of the relationship between

the source data and the analysis objectives and possible limitations inherent in a given

data type with respect to the desired level of information. A specific consideration

would be the ability or inability of an image data type to discern individual floristic

categories defined in the classification scheme.

4. Formalize the design of the map units. Following the design of the map units, map

unit keys, and descriptions are developed. The logic of the map unit design is defined

in a dichotomous key for the map units. The key illustrates the hierarchical and

mutually exclusive relationship of all map units. See appendix 3A for examples of

map unit keys associated with several vegetation characteristics. Map unit descriptions

are developed to describe the taxonomic unit composition of each map unit.

Elements of Quality Map Unit Design

At a minimum, a map unit design must be the following:

• Exhaustive. The map units that result from the design process must account for the

full range of conditions of interest found in the project area. In addition to the vegetation classifications addressed by the protocol contained in this technical guide,

other land cover classifications needed to meet analysis objectives should be included

(e.g., urban, agriculture, barren, and water).

• Mutually exclusive. Any specific vegetation condition must be assignable to one

and only one map unit.

• Field applicable. The logic in the map unit design must be applicable to field

observations and/or field sampled data.
3-22 Existing Vegetation Classification & Mapping Technical Guide

3.2.3.2 Map Feature Design

Map feature design identifies the spatial characteristics and structure of individual areas

or delineations on a map. Specific map features are nonoverlapping and geographically

unique and may contain more than one thematic element (map units). Two key components

of map feature design are setting the size of the minimum map feature and determining

how the map features will be delineated. The term “minimum map feature,” as used in

this technical guide, is analogous to minimum map unit (MMU) as used widely in the

past. National standards for the minimum map feature at each map level have been

established and are described in section 3.2.2. Keep in mind that local business needs

may dictate the delineation of smaller landscape features, such as small water bodies

or riparian areas, below the size of minimum map feature standard. 

Determine the Minimum Map Feature

1. Define the user needs. The ideal level of detail and the intended use of the data

must be clearly defined.

2. Identify the source image data to be used. Consider the ability or inability of the

source image data to discriminate vegetation/landscape features considered important

in step 1.

3. Determine the methodology to use for feature delineation.

Methods for map feature delineation are described in greater detail in section 3.2.4.

3.2.3.3 Map Design Examples

This section provides several simple map design examples to illustrate the map unit

design and map feature design process relationships. 

Example 1

A mapping project is proposed where the user identifies the need for a geospatial database

and map product depicting order-level physiognomic type taxonomic units. The map unit

design process determines that map units can be developed to directly correspond to the

taxonomic units. These relationships are listed in table 3.12. Note that the taxonomic class

Table 3.12. Physiognomic type classification taxonomic units and map units.

Physiognomic type classification Physiognomy map

Order-level taxonomic units Order-level mapping units

Vegetation not dominant Sparse vegetation

Tree dominated Tree vegetation

Shrub dominated Shrub vegetation

Herb dominated Herbaceous vegetation

Nonvascular dominated Nonvascular vegetation
Existing Vegetation Classification & Mapping Technical Guide 3-23

“vegetation not dominant” is designed to also include areas with less than 1-percent vegetation. Figure 3.2 illustrates map features depicting these map units. 

Example 2

A mapping project is proposed in which the user identifies the need for a geospatial

database and map product depicting dominance type taxonomic units. The map unit

design process identifies map units that are consistent with the user needs and can be

produced within the limitations of mapping technology. Table 3.13 lists these relationships.

Figure 3.3 illustrates map features depicting these map units.

Example 3

A mapping project is proposed where the user identifies the need for a geospatial database

and map product depicting tree canopy cover technical groups. The map unit design

process identifies the mid-level map units described by the protocol contained in this

technical guide as appropriate for the user needs and consistent with current mapping

Table 3.13. Dominance type classification taxonomic units and map units.

Dominance type classification Dominance type map

Taxonomic units Mapping units

Tree SP. 1 Tree SP. 1 and 2

Tree SP. 2

Tree SP. 3 Tree SP. 3

Shrub SP. 1 Shrub SP. 1

Shrub SP. 2

Herbaceous SP. 1 Herbaceous SP. 1 and 2

Herbaceous SP. 2

Nonvascular SP. 1 Nonvascular SP. 1 and 2

Nonvascular SP. 2

Sparse vegetation Sparse vegetation

Figure 3.2. Physiognomic types. Figure 3.3. Dominance types.
technology. Table 3.14 lists these relationships. Figure 3.4 illustrates map features

depicting these map units. 

Example 4

A mapping project is proposed where the user identifies the need for a geospatial database and map product depicting dominance type taxonomic units as well as tree canopy

cover technical groups. The map unit design process recognizes that these map units are

a combination of the map units from examples 2 and 3 and, therefore, are all unique

combinations of the two sets. Table 3.15 lists these relationships. 

Figure 3.5 illustrates map features depicting these map units.

Examples 1 through 4 represent simple single-purpose mapping projects in which the

relationships between the taxonomic units and technical groups of the classifications and

map units of the map product are fairly direct. In practice, however, most mapping projects

3-24 Existing Vegetation Classification & Mapping Technical Guide

Table 3.14. Tree canopy cover classification technical groups and map units.

Tree canopy cover classification Tree canopy cover map

Tree canopy cover technical groups (%) Tree canopy cover mapping units

0 Sparse vegetation

1–9.9 

10–19.9 10–29

20–29.9 

30–39.9 30–59.9

40–49.9 

50–59.9 

60–69.9 60–79.9

70–79.9 

80–89.9 80–100

90–100 

Figure 3.4. Tree canopy cover. Figure 3.5. Combined dominance type and tree

canopy cover.
Existing Vegetation Classification & Mapping Technical Guide 3-25

Table 3.15. Combined dominance type and tree canopy cover classification map units.

Dominance type Combined dominance 

cover

Tree canopy cover type and tree canopy 

Mapping units Mapping units Mapping units 

(% canopy cover) (% canopy cover)

Tree SP. 1 and 2 10–29.9 Tree SP. 1 and 2; 10–29.9

30–59.9 Tree SP. 1 and 2; 30–59.9

60–79.9 Tree SP. 1 and 2; 60–79.9

80–100 Tree SP. 1 and 2; 80–100

Tree SP. 3 10–29.9 Tree SP. 3; 10–29.9 

30–59.9 Tree SP. 3; 30–59.9 

60–79.9 TREE SP. 3; 60–79.9 

80–100 TREE SP. 3; 80–100

Shrub SP. 1 No tree canopy cover SHRUB SP. 1; 

no tree canopy cover

Herbaceous SP. 1 and 2 No tree canopy cover Herbaceous SP. 1 and 2; 

no tree canopy cover

Nonvascular SP. 1 and 2 No tree canopy cover Nonvascular SP. 1 and 2; 

no tree canopy cover

Sparse vegetation No tree canopy cover Sparse vegetation; 

no tree canopy cover

are implemented to meet more general purposes. In most cases, mapping projects produce

geospatial databases that contain all the map units (physiognomic, floristic, and structural)

that are included in this protocol for any given level of mapping. This will generally require

differentiating and delineating map features based on complex map unit design criteria that

incorporate all the taxonomic units and technical groups from all the vegetation classifications being mapped. When the delineation of each map feature is based on all applicable

vegetation classifications (physiognomic, floristic, and structural) the resulting geospatial

database provides a flexible tool for a wide variety of analysis objectives.

3.2.4 Map Product Development and Assessment

In this section:

• General overview of the mapping process 

• Steps to producing mid and base-level vegetation maps

• Technical discussion of data sources and mapping methods used in the production

of vegetation maps 

The information in section 3.2.4 is presented in a format analogous to three tiers of a

pyramid. The top tier provides an overview of the general process categories that comprise

an entire mapping project. The second tier summarizes the activities performed in each
3-26 Existing Vegetation Classification & Mapping Technical Guide

of those processes specifically for mid- and base-level map development. The third and

most technical tier presents a number of methodological considerations for performing

mapping activities. These considerations are based on existing and former mapping

efforts in the Forest Service and are intended to provide insight into appropriate data

sources and technologies currently available for map development. These considerations

are neither exhaustive nor the only means for implementing vegetation mapping. Project

managers and analysts should conduct a thorough mapping process investigation.

The three-tiered approach in this section’s organization is designed to make this

technical guide useful to a broad audience with varying levels of need for understanding

the mapping process. Program managers may only need a general process outline to

understand basic resource requirements whereas a mapping analyst requires a more

technical understanding of the data and technologies applied.

3.2.4.1 Vegetation Mapping Overview

Producing a vegetation map to the standards specified in this document is a multidisciplinary

activity. Beginning with classification of the vegetation communities described in section

2 through the finalization of a geographical information systems (GIS) database and

associated metadata, a series of processes must be completed using the skills contained

in several resource and technical fields (e.g., vegetation ecologist, field forester, GIS

technician, remote sensing specialist/photogrammetrist). When considered at its most basic

level, vegetation map production can be summarized by the following process categories.

1. Identify mapping project based on information need.

2. Identify the mapping system and its relevant components.

3. Develop a project plan. 

4. Assemble the resources necessary to produce a map including people, hardware/software, and data.

5. Perform the actual mapping tasks.

6. Conduct an accuracy assessment.

7. Build GIS database and associated metadata.

8. Update data on a cyclical basis.

Timeframes for accomplishing the processes related to initial map production are

dependent on geographic extent, map level, and resource availability. To be successful,

mapping projects may easily span more than 1 year and represent a significant commitment

of resources. Furthermore, these products should be viewed as “living maps” to be

maintained on a regular basis versus one-time investments that will quickly become

outdated and have limited value for resource monitoring.

Map product development and assessment are discussed in more detail for mid- and

base-level map products than for broad and national level products. Many of the same
Existing Vegetation Classification & Mapping Technical Guide 3-27

methods identified for the mid-level and/or through the aggregation of finer level maps

meeting the specified standards can be used to develop broad- and national-level map

products. Step-based processes for producing mid- and base-level maps are illustrated

and summarized in the following sections. 

3.2.4.2 Produce a Mid-Level Existing Vegetation Map

Figure 3.6 illustrates the processes necessary to develop a mid-level map product that

meets the map standards identified in section 3.2.2. Processes for mapping additional

attributes required at the regional or local level will need to be identified and described

by the local data stewards. Appendix 3C includes examples of mid-level mapping protocols

in operational use in the agency.

Figure 3.6. Map Product Development and Assessment Mid-Level Vegetation Mapping.
3-28 Existing Vegetation Classification & Mapping Technical Guide

Table 3.16. Mid-level mapping methods.

Map attribute Appropriate mapping methods 

Physiognomic order Generalized from Physiognomic class 

Physiognomic class Generalized from cover or dominance type

Physiognomic subclass Supervised/unsupervised image classification

Cover type (e.g., SRM/SAF) Spatial modeling based on ecological predictors and existing cover type, 

augmented with image classification

Dominance type Spatial modeling based on ecological predictors and existing 

physiognomic class, augmented with image classification

Total vegetation cover Supervised/unsupervised image classification

Tree canopy closure • Supervised/unsupervised image classification

• Image based modeling

• Hybrid classification (classification-plot regression) 

Tree diameter • Supervised/unsupervised image classification

• Hybrid classification (classification-plot regression) 

Anderson 1 classa Supervised/unsupervised image classification

a Required for polygons with less than 10-percent total vegetation cover.

Steps to Produce a Mid-Level Vegetation Map

The steps below are presented in the general chronological order in which they occur,

although variation in mapping methods and availability of existing data and resources

may alter the progression in a given project.

Step 1: Design map units. Identify existing floristic classifications for plant associations

or dominance types for the area being mapped. Identify plant associations or dominance

types that are to be mapped as compositional groups or vegetation complexes map units.

Step 2: Acquire and prepare the necessary data. Identify and acquire primary and ancillary data appropriate for mid-level map development (table 3.16). Process the primary

data to ensure adequate geospatial registration and data content. Evaluate and process

ancillary data to ensure appropriate scale, georegistration, and extent.

• Acquire and process appropriate primary image data to be used for delineation and

classification:

- Radiometric correction.

- Geometric correction.

- Terrain correction.

- Generate derivative data—e.g., Normalized Difference Vegetation Index (NDVI),

Principal Component Analysis (PCA), texture.

- Mask imagery to subproject processing areas in project area extent.

• Gather ancillary data, determine utility, and process for project use:

- Consider the appropriate resolution and/or scale of capture.

- Reproject to desired projection, if necessary.

- Clip/mask to project area extent.

- Generate derivative layers—e.g., slope/aspect, hillshade, layer buffers.
Existing Vegetation Classification & Mapping Technical Guide 3-29

Step 3: Delineate vegetation and landscape features. Delineate continuous patches of

similar vegetation composition and structure based on primary data source and consistency

with the map unit design. Use computer-based systematic methods of generating polygons

(image segmentation) or integrate/aggregate from existing base-level maps. Section 3.2.4.4

includes additional information on image segmentation and thematic aggregation.

• Prepare inputs for image segmentation:

- Layer stack segmentation inputs (image bands, image derivatives, and 

ancillary data).

• Integrate base-level maps where they exist:

- Aggregate detailed map units to required level in the classification hierarchy.

- Aggregate below minimum map features to required minimum map feature size, 

if necessary, using adjacency and similarity logic.

Step 4: Assemble and collect reference data required for mapping and accuracy assessment. Gather existing plot data and/or collect new plot and/or photointerpretation data

and summary observation data to use for computer training, model development, interim

map assessment, and final accuracy assessment. 

• Assemble existing plot data and evaluate for sample intensity and data content to

determine utility for development or assessment.

• Collect new plot data and/or photointerpretation data for map development or accuracy

assessment.

• Conduct rapid assessments to gather extensive summary data for training, ecological

model rule development, and interim map assessments.

Step 5: Assign attributes to map features (polygons). Map each standard attribute independently in a hierarchical process, applying appropriate image classification and/or

modeling techniques (table 3.16). Map more general attributes (subclass) first and

subsequently use as stratification for tree-specific attributes (dominance type, canopy

closure, and size) to increase process efficiency. Field and/or photographically review

and correct map units for nonsystematic error. 

• Map standard attributes:

- Classify imagery for subclass and edit results.

- Classify imagery for Anderson 1 land cover types. 

- Classify imagery to total vegetation cover.

- Model/classify dominance types in mapped subclass categories.

- Classify structure in mapped subclass categories.

- Map additional attributes.
3-30 Existing Vegetation Classification & Mapping Technical Guide

Step 6: Move maps into a corporate database format and apply crosswalks to complete

the database hierarchy and link to other classification systems. Combine independently

mapped attributes into a corporate database structure (appendix 3F) and audit/rectify

database anomalies. Apply crosswalks to populate upper levels of the hierarchy and

additional classification systems identified for local needs.

• Create a single geospatial database containing all mapped attributes. 

• Add remaining database elements of the corporate database structure.

• Apply crosswalks to populate upper levels of the hierarchy and additional

classification systems.

• Overlay with other GIS layers to populate additional attributes.

• Audit the database and spatial layer for substandard anomalies, GIS errors, and

illogical map attribute combinations.

Step 7: Conduct a map accuracy assessment. Using an independent reference dataset,

compare labeled reference data to map labels to generate error matrixes for each map

attribute/class. Consider generating fuzzy set accuracy assessments in addition to standard

error matrices.

• Assemble independent reference dataset: Calculate attribute labels from data. 

• Compare labeled reference data with map labels for each attribute:

Evaluate spatial relationships of reference data to map features to determine the 

validity of individual reference data records for map assessment.

• Generate error matrices.

• Analyze error structure relative to the map unit design to identify possible aggregation

or other changes to improve accuracy.

Step 8: Finalize FGDC-compliant and additional metadata.

• Populate FGDC-compliant metadata template (appendix 3E).

• Compile additional compendium of more detailed source data and methods 

documentation created during the mapping process.

• Create archive of project data backups and documentation.

3.2.4.3 Produce a Base-Level Map

Figure 3.7 illustrates the processes necessary to develop a base-level map product meeting

the map standards identified in section 3.2.2. Processes for mapping additional attributes

required at the regional or local level will need to be identified and discussed by the

local data stewards.
Existing Vegetation Classification & Mapping Technical Guide 3-31

Steps to Produce a Base-Level Vegetation Map

The steps below are presented in the general chronological order they occur, although

variation in mapping methods and availability of existing data and resources may alter

the progression in a given project.

Figure 3.7. Map Product Development and Assessment Base-Level Vegetation Mapping.
3-32 Existing Vegetation Classification & Mapping Technical Guide

Table 3.17. Base-level mapping methods.

Map attribute Appropriate mapping methods 

Physiognomic order Generalized from physiognomic class

Physiognomic class Generalized from plant alliances

Physiognomic subclass Photo/image interpretation with field observations

Cover type Generalized from plant alliances

Dominance type Generalized from plant alliances

Alliances Spatial modeling based on ecological predictors (e.g., topography, 

climate, geology) and existing physiognomic type, augmented with 

photo/image interpretation and field observation

Associations Field observation

Total vegetation cover Photo/image interpretation with field observations

Tree canopy closure Photo/image interpretation with field observations

Tree diameter Photo/image interpretation with field observations

Anderson 1 class Photo/image interpretation with field observations

Step 3: Assemble and collect reference data necessary for mapping and accuracy assessment. Gather existing plot data and/or collect new plot and summary observation data to

be used for interpreter calibration, model development, interim map assessment, and

final accuracy assessment. 

• Assemble existing plot data and evaluate it for sample intensity and data content to

determine utility for development or assessment.

• Collect new plot data for map development or accuracy assessment.

• Conduct rapid assessments to gather extensive summary data for ecological model

rule development and interim map assessments.

Step 1: Design map unit. Identify appropriate floristic classification of plant associations

and alliances in the area to be mapped. Determine which, if any, plant associations will

be mapped as compositional groups or vegetation complexes map units. If formal classifications for some or all the existing vegetation do not exist, complete vegetation sampling

and classification before proceeding with mapping. 

Step 2: Acquire and prepare the necessary data. Identify and acquire primary and ancillary

data appropriate for base-level map development (table 3.17). Evaluate and process

ancillary data to ensure appropriate scale, georegistration, and extent. 

• Acquire primary photo/image data:

- Appropriate photo scale to identify map attributes.

- Orthorectify digital data, if necessary.

• Gather ancillary data, determine utility, and process for project use:

- Consider appropriate resolution and/or scale of capture.

- Reproject to desired projection system if necessary.

- Clip/mask to project area extent, including buffer.

- Generate derivative layers—e.g., slope/aspect, hillshade, layer buffers.
Existing Vegetation Classification & Mapping Technical Guide 3-33

Step 4: Delineate vegetation and landscape features. Delineate continuous patches of

similar vegetation composition and structure based on primary data source. Delineations

are determined through photography and/or image interpretation and registered to a

digital image base. Feature delineation and attribution can occur simultaneously for map

attributes that are readily interpreted on large-scale photography. 

• Calibrate interpretation analyst based on reference data and mensurational guides

that illustrate crown densities and diameters at various photo scales.

• Delineate vegetation stands or patches containing uniform or evenly distributed

vegetation structure and top layer species composition. Digitize delineations over a

digital image base. 

• Adjust delineations for species composition, if necessary, based on field observations.

Step 5: Assign attributes to map features (polygons). Map each standard attributes that

can reliably be interpreted from stereoscopic photography and associated high-resolution

imagery (table 3.17). Attributes not reliably mapped from image/photointerpretation

should be mapped based on field observation.

• Map standard attributes:

- Interpret photography/imagery for subclass and label polygons.

- Interpret photography/imagery for tree canopy closure.

- Interpret photography/imagery for tree diameter class.

- Interpret photography/imagery for Anderson 1 land cover types and label polygons.

- Interpret photography/imagery for total vegetation cover.

Label polygons with vegetation alliances based on modeling, photograph/image interpretation, and field observation.

• Map additional attributes.

Step 6: Move maps into a corporate database format and apply crosswalks to complete

the database hierarchy and link to other classification systems. Combine mapped attributes

in a corporate database structure (appendix 3F) and audit/rectify database anomalies. 

• Create a single geospatial layer containing all mapped attributes as separate database

elements.

• Add remaining database elements of the corporate database structure.

• Apply crosswalks to populate upper levels of the hierarchy and additional classification

systems identified for local needs.

• Overlay with other GIS layers to populate additional attributes not related to vegetation.

• Audit the database and spatial layer for substandard anomalies, GIS errors, and

illogical map class combinations between attributes.
3-34 Existing Vegetation Classification & Mapping Technical Guide

Step 7: Conduct a map accuracy assessment. Using an independent reference dataset,

compare labeled reference data to map labels to generate error matrices for each map

attribute/class. Consider generating fuzzy set accuracy assessments in addition to standard

error matrices.

• Assemble independent reference dataset. Calculate attribute labels from data. 

• Compare labeled reference data with map labels for each attribute. Evaluate spatial

relationship of reference data to map features to determine the validity of individual

reference data records for map assessment.

• Generate error matrices.

Step 8: Finalize FGDC-compliant and additional metadata. Populate FGDC metadata

template (appendix 3E). 

• Populate FGDC-compliant metadata template.

• Compile additional compendium of more detailed source data and methods documentation created during the mapping process.

• Create archive of project data backups and documentation.

3.2.4.4 Principles of Map Product Development and Assessment

Existing Information Sources

Vegetation mapping across the range of map levels outlined in the protocol described in

this technical guide is primarily accomplished through the use of remotely sensed image

data. These data can be acquired from airborne or spaceborne platforms and can be in

photographic or digital form. A brief explanation of remote sensing systems, common

remote sensing data sources, and the methods used to extract thematic information will

provide insights into the similarities and differences of vegetation mapping approaches

based on photographic or digital data.

“Remote sensing is the science and art of obtaining information about an object,

area, or phenomenon through the analysis of data acquired by [a] device that is not in

contact with the object, area, or phenomenon under investigation” (Lillesand and Kiefer

1987). The remote sensing data sources noted in this section are the products of complex

systems. Although a thorough description of these systems and the energy-matter interactions that affect the basic nature of these data is beyond the scope of this protocol. To

understand the differences in how information is extracted from these data and how this

information relates to the attributes and standards for vegetation maps, however, requires

a brief overview. For detailed descriptions, refer to Campbell (1987), Lillesand and

Kiefer (1987), and Jensen (1996).

In their simplest form, the complex matter/energy interactions involved in passive

electromagnetic remote sensing are described by three basic processes: (1) energy from
Existing Vegetation Classification & Mapping Technical Guide 3-35

the sun propagates through the atmosphere where it (2) interacts with earth surface features and (3) is retransmitted through the atmosphere and becomes available to a remote

sensing device. The atmosphere has a substantial effect on the intensity and spectral

composition of energy available to remote sensing system. These effects result primarily

from atmospheric scattering and absorption. Spaceborne sensors are changed more by

the atmosphere than the airborne sensors because their energy source passes through the

full thickness of the atmosphere twice. Energy incident on any earth surface feature will

have various portions reflected, absorbed, and/or transmitted. The proportions of energy

that are reflected, absorbed, and/or transmitted vary for different surface features and

provide the basis for distinguishing different types of features in an image. Because of

the nature of the matter/energy interactions, two features may be indistinguishable in

one portion of the electromagnetic spectrum and easily distinguished in another. Many

remote sensing devices are designed to use this variable response and collect data in

several specific regions of the electromagnetic spectrum. A number of multispectral

image data sources are included in this section’s description of potential remote sensing

data sources. The other data sources collect data, color and panchromatic, only in the

visible portion of electromagnetic spectrum.

All the primary remote sensing data sources described are passive sensors of electromagnetic energy; that is, they all rely on the sun as their source of energy and sense/record

data in various portions of the electromagnetic spectrum. These data are digitally recorded

in the form of pixels and photographically recorded on crystals or grains of silver halide.

A pixel is defined as “a two-dimensional picture element that is the smallest nondivisional

element of a digital image.” For the purposes of describing the ground resolution of these

remote sensing data and discussing the extraction of information, a pixel and a grain of

silver halide are reasonably analogous; both represent the smallest nondivisible element

and an integrated signal of some area on the ground.

Development of map products at all levels depends on the acquisition of primary and

ancillary data sources. Primary data sources are those from which a map is directly derived;

ancillary data sources are used to support development and verification of the map. 

Primary Data. Primary data sources are most often continuous data that depict an uninterpreted image of surface condition at some moment in time. Many primary data

sources are logically used for map feature delineation and population. These include

satellite based multispectral and panchromatic imagery, as well as true color, infrared,

and panchromatic digital and hardcopy aerial photography. 

Table 3.18 lists commonly available examples of satellite borne sensor data that can

be used as a primary image data source. Table 3.19 lists minimum photographic scales

recommended for detecting and measuring various vegetation characteristics commonly
3-36 Existing Vegetation Classification & Mapping Technical Guide

Table 3.18. Available digital image data types.

Coverage Temporal

Data type (swath width) Spatial resolution Spectral resolution Appropriate

(km) (meters) resolution1 (days) map level

Landsat Multispectral Scanner (MSS) 185 82 G, R, NIR N/A Broad, national

Landsat TM 5, 7 185 6 at 30; B, G, R, NIR, MIR; 16 Mid, broad,

1 at 60; TIR national

1 at 15

(Landsat 7 only)

SPOT 2 60 3 at 20; G, R, NIR Pointable Mid, broad

1 at 10 (< 5) 

SPOT 4 60 4 at 20; G, R, NIR, MIR Pointable Mid, broad

1 at 10 (< 5)

SPOT 5 60 4 at 10, B, G, R, NIR MIR < 5 Base, bid

1 at 5, 

1 at 2.5

Indian Remote Sensing Satellite 1B (IRS-1B); 145; 4 at 72.5 B, G, R, NIR 22 Broad, national

(Live Internet Spectral Scanner [LISS 1]); LISS 2 74 4 at 36.25

European Remote Sensing Satellite 100 1 at 26 (Radar) Far Infrared; 35 Broad, national

1, 2 (ERS-1,2); (Active Microwave 4 at 1,000 B, G, R, NIR

Instrumentation [AMI]); (Along Track 

Scanning Radiometer [ATSR])

Resurs-01-3 600 4 at 160 B, G, R, MIR, TIR 21 Broad, national

1 at 700

National Oceanic and Atmospheric 2,700 5 at 1,100 G, R, MIR Daily National

Administration (NOAA); (Advanced Thermal

Very High Resolution Radiometer [AVHRR])

IRS-P4 (Ocean Colour Monitor [OCM]) 1,420 8 at 360 MIR 2 National

IKONOS 11 4 at 4 B, G, R, NIR 1–3 Base, mid

1 at 1

IRS-1C, D 142; 3 at 23; G, R, NIR, SWIR 24 Base, mid, 

70 1 at 70; broad

1 at 5.8

RADARSAT 500 1 at 9-100 Far Infrared 3 Mid, broad, 

(Radar) national

China-Brazil Earth Resources Satellites 1 113 5 at 20 B, G, R, NIR, 26 Mid, broad,

(CBERS-1); (Charge coupled device 120 2 at 260 MIR, thermal national 

[CCD]); (Wide Field Imager [WFI]) 900 3 at 80, 1 at 160

Infrared Multispectral Scanner (IRMSS)

Terra (Moderate Resolution Imaging 2,330 2 at 250, B, G, R NIR, Daily Mid, broad, 

Spectroradiometer [MODIS]); (Multiangle 360 5 at 500, MIR, thermal; national

Imaging Spectroradiometer [MISR]); 60 29 at 1,000; B, G, R, NIR;

(Advanced Spaceborne Thermal Emission 4 at 250; SWIR, VNIR, 

and Reflection Radiometer [ASTER]) 3 at 15, thermal

6 at 30, 5 at 90

OrbView-2 2,800 8 at 1,130 6 visible, 2 NIR Daily National

Orb View-3 8 4 at 4, 1 at 1 B, G, R, NIR < 3 Base, mid

Quickbird 2 17 4 at 2.5, 1 at 0.65 B, G, R, NIR 1–4 Base, mid

Earth Observing 1 (EO-1) (Advanced Land 37 1 at 10, B, G, R, NIR, 7 Mid, broad,

Imager [ALI]) (Hyperion) (Linear Etalon 7.6 9 at 20; MIR; Hyperspectral— national

Imaging Spectrometer Array 220 at 30; visible to MIR;

Atmospheric Corrector [LAC]) 256 at 250 Hyper—MIR to SWIR

1 B=blue, G=green, R=red, NIR=near infrared, MIR=mid infrared, TIR=thermal infrared, SWIR=short wave infrared, VNIR=visible near infrared/short wave.
Existing Vegetation Classification & Mapping Technical Guide 3-37

Table 3.18. Available digital image data types. (continued)

Coverage Temporal

Data type (swath width) Spatial resolution Spectral resolution Appropriate

(km) (meters) resolution1 (days) map level

Earth Resources Observation 12.7 1 at 0.82 Panchromatic Daily Base

Systems B1 (EROS-B1)

Aqua (MODIS) (Advanced Microwave 2,330 2 at 250, B, G, R, NIR, < 4 National 

Scanning Radiometer [AMSR]) 5 at 500, 29 at 1,000; MIR, Thermal, 

1 at 5 Far infrared

Sea-viewing Wide Field-of-view 1,502 8 at 1,100 B, G, R, NIR, 1 National 

Sensor (SeaWiFS) MIR, Thermal 1 B=blue, G=green, R=red, NIR=near infrared, MIR=mid infrared, TIR=thermal infrared, SWIR=short wave infrared, VNIR=visible near infrared/short wave.

Table 3.19. Photographic scales and resolution necessary for vegetation mapping.

Ground Minimum scale Minimum Scale Appropriate

Data requirements resolution (IR, CIR)a detection BWb, color) detection common scale 

(map units) (m) measurement measurement (IR, CIRa, BWb, color)

Vegetated cover

Tree stands 3 1:184,000 1:92,000 1:320,000 1:160,000 1:60,000 1:40,000

Tree species 0.1 1:3,200 1:1,600 1:5,000 1:2,500 Special project

Tree stand height class 0.3 1:12,500 1:6,400 1:20,000 1:9,600 1:12,000 1:12,000/1:16,000

Tree stand mean diameter 0.3 1:12,500 1:6,400 1:20,000 1:9,600 1:12,000 1:12,000/1:16,000

Tree stand crown closure 0.3 1:12,500 1:6,400 1:20,000 1:9,600 1:12,000 1:12,000/1:16,000

Shrub stands 3 1:184,000 1:92,000 1:320,000 1:160,000 1:60,000 1:40,000

Shrub species 0.3 1:12,500 1:6,400 1:20,000 1:9,600 1:12,000 1:12,000/1:16,000

Shrub stand height class 0.3 1:12,500 1:6,400 1:20,000 1:9,600 1:12,000 1:12,000/1:16,000

Shrub stand form class 0.3 1:12,500 1:6,400 1:20,000 1:9,600 1:12,000 1:12,000/1:16,000

Forb stands 3 1:184,000 1:92,000 1:320,000 1:160,000 1:60,000 1:40,000

Grass stands 3 1:184,000 1:92,000 1:320,000 1:160,000 1:60,000 1:40,000

Nonvegetated cover

Rock 3 1:184,000 1:92,000 1:320,000 1:160,000 1:60,000 1:40,000

Barren 3 1:184,000 1:92,000 1:320,000 1:160,000 1:60,000 1:40,000

Water 3 1:184,000 1:92,000 1:320,000 1:160,000 1:60,000 1:40,000

Land use 3 1:184,000 1:92,000 1:320,000 1:160,000 1:60,000 1:40,000

a IR=infrared, CIR=color infrared. b BW=panchromatic.

mapped. Other noncontinuous remotely sensed data are available—e.g., lidar (light detection

and ranging—but are difficult to apply as a primary source for the development of

continuous vegetation information, although they may be effectively used in conjunction

with continuous data sources.

When selecting an appropriate data source, consider several basic principles that

relate the grain of data to the size and shape of the vegetation/landscape elements that

constitute the pattern of interest. When the pattern of interest is smaller than the grain of

the data, the pattern cannot be detected. When the pattern of interest is much larger than

the grain of the data, that pattern can be well represented, provided it can be recognized

in those data. This is particularly true when the pattern is composed of spectrally

homogenous units organized in regular shapes (shape index approaching 1:1 and/or a
3-38 Existing Vegetation Classification & Mapping Technical Guide

fractal dimension approaching 1) (Nellis and Briggs 1989, Turner et al. 1989, Cullinan

and Thomas 1992, Simmons et al. 1992, and Ryherd and Woodcock 1996). For example,

a minimum map unit of 5 acres represented by approximately 22 Thematic Mapping (TM)

pixels, 75 Systeme Probatoire d’Observation de la Terre (SPOT) high resolution visible

imaging system (HRV) pixels, and 20,000 digital orthophoto pixels that is essentially

homogeneous would be detectable and reasonably well characterized by any of these

remote sensing data sources.

As the grain of the data interacts with the grain of the vegetation pattern, it creates a

problem referred to as boundary pixels. Boundary pixels are those pixels that are not completely filled by one homogenous class of scene object, in this case vegetation. If the area

on the ground is relatively uniform, the integrated signal and the resulting digital number

are reasonable representations of the area. The problem is created by pixels that represent

an area that contains the boundary of two or more features that differ in brightness. The

integrated signal of this area becomes an average of the two conditions and may not represent either condition well. If a given map unit is irregular in shape (high edge: interior ratio;

shape index much greater than 1:1, and/or a fractal dimension much greater than 1), the

proportions of boundary pixels increase relative to nonboundary pixels. A similar condition

develops when the pixels comprising an object are not spectrally homogenous. This pattern of heterogeneity results in difficulty segmenting the image into regions (Ryherd and Woodcock 1996). 

Selection of primary data sources for map production must be based on the ability

of the data to delineate and identify the standard and any supplemental map units. For

example, using a 1-kilometer ground resolution satellite image will not allow for the

delineation of map units that meet the minimum map feature standard defined for midlevel maps. A variety of satellite remote sensing data sources are available with highly

variable spatial, temporal, and spectral characteristics. Similarly, a wide range of aerial

photography data sources are available that also vary in their spatial, temporal, and spectral

characteristics. A single primary data source may not be adequate to delineate a complete

population of all map units. The map producer may need several primary data sources to

develop a complete map product. Subsequent factors determining selection of primary

data sources include data availability, quality, and cost. Other considerations should

include currency and temporal coincidence of image data.

Data Preparation. Prepare digital imagery for processing through the proper registration

and correction of raw data, with the objective of increasing the accuracy and interpretability

of the image before image classification. Three important image-preprocessing steps

(correction types) follow:

1. Radiometric correction accounts for variations in the image resulting from sensor

anomalies or environmental conditions, such as haze, so that image values represent

as closely as possible the true reflectance of land cover features. This step is optional
Existing Vegetation Classification & Mapping Technical Guide 3-39

and depends on the severity of the image defects and/or the project’s need to show

true reflectance values.

2. Geometric correction reorients the image to compensate for the Earth’s rotation and

variation in the satellite’s position and altitude. This process may also include positioning or warping an image in a map projection system so that accurate measurements

can be made. This step is necessary if the 

resulting classification products are used in GIS with other georeferenced information

layers. 

3. Terrain correction adjusts the image for the relief distortion with the help of digital

elevation data. Terrain correction is recommended if precise location is required and

the study area has relief differences greater than 500 feet.

Ancillary Data. Other data sources are available to use to support map unit delineation

and map unit population. These include vertical aerial photography, videography, digital

orthophoto quads, DEM, historical vegetation data and maps, other ecologically related

data and maps (e.g., soils and hydrography), and disturbance and land use information

(e.g., fire history, silvicultural treatments, urban succession). Consider the scale of capture

associated with an ancillary data source relative to the desired level of detail in the map

product and scale of the source data. For example, it may not be appropriate to rely on a

1:100,000-scale hydrographic layer to help map riparian related vegetation types at the midlevel. Conversely, at the mid-level, a 1:24,000 DEM can greatly enhance the ability to map

the distribution of vegetation types constrained by elevation. Also consider using multiple

ancillary datasets or map layers that vary greatly in scale. Spatial and thematic accuracy

may vary considerably between sets of information. Spatial coregistration may be necessary

to appropriately use two or more independent layers as inputs into the same process.

Map Feature Delineation

Criteria are established to use when spatially differentiating map features between map

units. Those criteria describe structural, floristic, and physiognomic characteristics of

the vegetation to be mapped, as well as nonvegetated landscape elements. In the context

of the protocol described in this technical guide, the delineation of map features depicting

the vegetation configuration across the landscape representing elements of vegetation

pattern can be synonymous with landscape patch delineation or stand delineation. The term

“patch,” as defined in Forman (1995), is “a relatively homogenous nonlinear area that

differs from its surroundings.” This definition is consistent with other common reference

texts, including Picket and White (1985) and Forman and Godron (1986), and also with

the common use of the term in the landscape ecology literature (Hartgerink and Bazzaz

1984, Scheiner 1992). Patch can specifically describe forested patches, nonforest vegetation patches, rock/barren patches, or water patches. 
3-40 Existing Vegetation Classification & Mapping Technical Guide

In contrast, the term “stand” has long been used to refer to the basic unit of forest

management (Toumey 1937). It also has been used as the basic unit of mapping and inventory (Graves 1913). A stand is defined as “a community, particularly of trees, possessing

sufficient uniformity as regards composition, age, spatial arrangement, or condition, to

be distinguishable from adjacent communities, so forming a silvicultural or management

entity.” This definition, from the SAF’s Terminology of Forest Science, Technology,

Practice, and Products (Ford-Robertson 1971), is consistent with definitions in a variety

of reference texts including Toumey (1937), Smith (1986), Oliver and Larson (1990),

Lincoln et al. (1982), and the definition provided in the USDA Forest Service Silvicultural

Practices Handbook (FSH 2409.17). Historically, most vegetation mapping completed

by the agency has been conducted through delineation of forest stands. In the context of

the protocol that this technical guide covers, the terms “patch” and “stand” may be synonymous depending on the degree that management considerations are incorporated into

stand delineations along with compositional and structural characteristics. Because many

past stand delineations contain multiple vegetation conditions and map units, they would

be multiple map features in any new mapping effort.

Guidelines for Map Feature Delineation

Image Interpretation. Image interpretation is the systematic examination of image data.

This frequently involves other supporting materials, such as maps and field observations

(Lillesand and Kiefer 2000). “The basis for delineation of map units is normally discontinuities in texture (reflecting life form composition, stocking, tree crown size differences,

and/or apparent tree height” (Stage and Alley 1973). If map feature delineation is completed with aerial photography, the process normally uses stereoscopic vertical aerial

photography. This process involves transferring the photo delineations to a base map and

converting to a digital form. An alternative image interpretation technique involves

interpreting stereoscopic pair aerial photography in conjunction with high-resolution,

digital imagery interpretation. An advantage of simultaneous onscreen delineation is the

creation of an immediate digital product. Photographic and digital image interpretations

without using stereoscopic photographic pairs suffer from the constraint of a one-dimensional depiction of vegetation cover. Image interpretation is the most intuitive form of

map feature delineation but is also the most subjective and least cost effective. 

Image Segmentation. As stated in Ryerd and Woodcock (1996), “Image segmentation is

the process of dividing digital images into spatially cohesive units, or regions. These

regions represent discrete objects or areas in the image.” If map feature delineation is

completed with digital imagery, the process typically uses data from spaceborne remote

sensing platforms. The basis for map unit delineation is usually the segmentation and

merging of raster data based on spectral characteristics and spatial arrangement. This
Existing Vegetation Classification & Mapping Technical Guide 3-41

Table 3.20. Data sources and methods for map feature delineation.

Minimum map 

Map level feature standard Data sources Delineation methods

(acres)

National 500 Medium to coarse resolution multispectral or panchromatic Data aggregation of broad or midimagery (30 m–1 km); existing broad or mid-level level maps; image segmentation

vegetation maps

Broad 20 Medium resolution multispectral or panchromatic Data aggregation of mid- or baseimagery (10–30 m), small scale photography level maps; image segmentation; 

(1:40,000–1:80,000), existing mid- and base- image interpretation

level maps

Mid 5 Fine to medium resolution multispectral or panchromatic Image segmentation; image

imagery (1–30 m), mid-scale photography interpretation; data aggregation

(1:15,840–1:40,000), existing base-level maps of base-level maps

Base 5 Fine resolution multispectral or panchromatic imagery Image interpretation

(< 5 m), large scale photography (1:5,000–1:15,840)

segmentation and merging process is influenced by the variance structure of the image

data and provides the modeling units that reflect life form composition, stocking, tree

crown size differences, and other vegetation/land cover characteristics. Because the image

data are geospatial data, the delineations do not have to be transferred to a base map.

Image segmentation is the most objective and typically lowest cost approach to map feature

delineation but is the farthest removed from human intuition. Image segmentation is most

often used to develop mid and broad level map products because it offers substantial

spatial detail in a consistent and repeatable fashion over large areas. 

Thematic Aggregation. Thematic aggregation is the process of combining spatially distinct

map features based on their categorical similarity and spatial arrangement. Thematic

aggregation is not a stand-alone approach to feature delineation. Feature delineations

generated at lower levels in the hierarchy, however, may preclude the need to directly

delineate features at higher levels. If map features are derived through aggregation routines,

a clear set of aggregation parameters or rules must be developed. Aggregation parameters

must consider the thematic relationship of potentially merged features (e.g., the aggregation

of two similar tree types is more desirable than the aggregation of a tree type and a nonvegetated class). Aggregation parameters are defined by thematic similarity and composition

of the aggregated feature and are ideally based on a hierarchical classification scheme. 

Aggregation as a means of feature delineation is most commonly applied at the

coarsest map levels and, if applied at the mid-level, should only supplement more direct

delineation techniques. Base-level mapping presumes that no finer continuous map

product exists, and aggregation is not an applicable technique. 

Map feature aggregation that have an areal extent below the minimum map feature

standard should be performed using logic that aggregates based on thematic similarity of

map unit attributes versus longest shared perimeter (e.g., opening the longest shared arc).
3-42 Existing Vegetation Classification & Mapping Technical Guide

Tables 3.21A and 3.21B offer simple guidelines for developing a merge routine that will

minimize the variability of a map unit in a map feature associated with merging adjacent

features. 

Map Feature Attribution

The process of mapping vegetation characteristics and assigning map unit labels or category

to each map feature is referred to as map feature attribution. At a minimum, each map

feature is attributed with a category from each standard map unit defined in section 3.2.2.

The map feature attribution process is typically applied in two steps: (1) classifying the

landscape in terms of the map units, and (2) labeling map features (polygons) with map

attributes. Depending on the mapping methodology, these two steps can be applied simultaneously or successively. Image interpretation usually accomplishes these two steps simultaneously; image classification often separates these two steps into two distinct processes. 

Table 3.21A. Aggregation logic—if physiognomic order is different than any adjacent map feature.

Adjacent Below minimum Below minimum Below minimum Below minimum Below minimum

feature feature—tree feature—shrub feature—herbaceous feature—no feature—nonorder order order dominant vegetated

Tree order Different Merge second Merge fourth Merge fourth Merge fourth

Shrub order Merge first Different Merge third Merge third Merge third

Herbaceous order Merge second Merge first Different Merge second Merge second

No dominant—sparse Merge third Merge third Merge first Different Merge first

Nonvegetated Merge fourth Merge fourth Merge second Merge first Different

Table 3.21B. Aggregation logic—if physiognomic order is the same as at least one adjacent map feature.

Map Herbaceous Herbaceous Herbaceous

unit attribute Priority order order order

Floristics 1 Different—merge N/A N/A

Physiognomic subclass 2 Same Different—merge N/A

Physiognomic class 3 Same Same Different—merge

Map 

unit attribute Priority Shrub order Shrub order Shrub order Shrub order

Shrub cover 1 Different —merge N/A N/A N/A

Floristics 2 Same Different—merge N/A N/A

Physiognomic subclass 3 Same Same Different—merge N/A

Physiognomic class 4 Same Same Same Different —merge

Map 

unit attribute Priority Tree order Tree order Tree order Tree order Tree order

Tree cover 1 Different—merge N/A N/A N/A N/A

Tree size 2 Same Different—merge N/A N/A N/A

Floristics 3 Same Same Different—merge N/A N/A

Physiognomic subclass 4 Same Same Same Different—merge N/A

Physiognomic class 5 Same Same Same Same Different—merge

Floristics in tables 3.21A and 3.21B refer to map units based on classification systems of cover type, dominance type, or plant alliances.
Existing Vegetation Classification & Mapping Technical Guide 3-43

The methods used to map vegetation characteristics may vary by map attribute and

level. As with the selection of image data sources, all possible methods are not appropriate across the range of map levels. The following section describes the appropriate

methods used to map the standard attributes at the mid- and base-levels. The appendixes

present specific examples of mapping methodologies that have been successfully used

in the Forest Service. The standards defined in section 3.2.2 and the guidelines provided

in conjunction with the associated examples should enable the development of a vegetation mapping work plan and/or the development of mapping contract specifications.

As previously described, vegetation mapping across the range of map levels outlined

in the protocol covered in this technical guide is primarily accomplished by using remotely sensed image data. Map feature attribution is therefore a remote sensing classification

or interpretation process. The methods explained herein apply to the base and mid-level

map products based on the assumption that broad and national level maps are generalizations of the mid-level map features and will be generated by aggregating those data. 

Many common textbooks on digital image processing of satellite remote sensing data

and interpretation of aerial photography cover the process of extracting information from

remotely sensed data, or “decoding” information from raw uninterpreted images. Image

classification of satellite remote sensing imagery and interpretation of aerial photography

are analogous processes. Both processes are data models intended to represent complex

natural systems. On the most basic level, the image interpretation and classification

processes are essentially the same; both processes group similar objects and label them

with some form of thematic information. Beyond this most basic level, however, each of

these processes has some fundamental differences related to the basic remote sensing data,

the analytical logic and methods, and the “tools” used to extract the information.

The following sections briefly outline and describe the image interpretation process

(not limited to aerial photography interpretation) and the satellite image classification

process. These two processes are explained together to illustrate their relationships. To

remain within the scope of the protocol covered in this technical guide, the tasks for

each process are only summarized. The basic task descriptions generally follow Avery

(1977), Estes et al. (1983), Simonett et al. (1983), Campbell (1987), Lillesand and

Kiefer (1987), Jensen (1996), and Lachowski et al. (1995 and 1996). Other textbooks

and the remote sensing literature offer many minor variations on the basic tasks

described. Similarly, the elements of image interpretation presented are also fairly common in the aerial photography interpretation literature

Elements of Image Interpretation. These elements, with some variation, are fairly common

in the aerial photography interpretation literature (Avery 1977, Estes et al. 1983, Simonett

et al. 1983, Campbell 1987, Lillesand and Kiefer 1987, Jensen 1996); most of them

have analogies in satellite imagery classification. 
3-44 Existing Vegetation Classification & Mapping Technical Guide

• Image tone denotes the lightness, darkness, and/or color of a region in an image.

Values for each cell in each band in multispectral data would be analogous. For more

information, refer to remote sensing literature that relates primarily to this element.4

4 Hixson, M.; Scholz, D.; Fuhs, N.; Akiyama, T. 1980. Evaluation of several schemes for classification of remotely sensed data.

Photogrammetric Engineering and Remote Sensing. 46: 1547–1553, Strahler, A.H. 1980. The use of prior probabilities in maximum

likelihood classification of remotely sensed data. Remote Sensing of Environment. 10: 135–163, Crapper, P.F.; Hynson, K.C. 1983.

Change detection using Landsat photographic imagery. Remote Sensing of Environment. 13: 291–300, Crist, E.P.; Kauth, R.J. 1986.

The tasseled cap de-mystified. Photogrammetric Engineering and Remote Sensing. 52: 81–86, Shasby, M.; Carneggie, D. 1986.

Vegetation and terrain mapping in Alaska using Landsat MSS and digital terrain data. Photogrammetric Engineering and Remote

Sensing. 52: 779–786, Fung, T.; LeDrew, E. 1987. Application of principal components analysis to change detection. Photogrammetric

Engineering and Remote Sensing. 53: 1649–1658, Chavez, P.S.; Bowell, J.A. 1988. Comparison of the spectral information content of

Landsat thematic mapper and SPOT for three different sites in the Phoenix, Arizona region. Photogrammetric Engineering and Remote

Sensing. 54: 1699–1708, Chuvieco and Congalton 1988, Leprieur, C.E.; Durand, J.M. 1988. Influence of topography on forest

reflectance using Landsat thematic mapper and digital terrain data. Photogrammetric Engineering and Remote Sensing. 54: 491–496,

Chavez, P.S.; Kwarteng, A.Y. 1989. Extracting spectral contrast in Landsat thematic mapper image data using selective principal component analysis. Photogrammetric Engineering and Remote Sensing. 55: 339–348, De Cola, L. 1989. Fractal analysis of a classified

Landsat scene. Photogrammetric Engineering and Remote Sensing. 55: 601–610, Hepner, G.F.; Logan, T.; Ritter, N.; N. Bryant. 1990.

Artificial neural network classification using a minimal training set: comparison to conventional supervised classification.

Photogrammetric Engineering and Remote Sensing. 56: 469–473, Mausel, P.W.; Kramber, W.J.; Lee, J.K. 1990. Optimum band selection

for supervised classification of multispectral data. Photogrammetric Engineering and Remote Sensing. 56: 55–60, Wang, F.1990.

Improving remote sensing image analysis through fuzzy information representation. Photogrammetric Engineering and Remote

Sensing. 56: 1163–1169, Cetin, H.; Levandowski, D.W. 1991. Interactive classification and mapping of multi-dimensional remotely

sensed data using n-dimensional probability density functions (nPDF). Photogrammetric Engineering and Remote Sensing. 57:

1579–1587, Cohen, W.B. 1991. Response of vegetation indices to changes in three measures of leaf water stress. Photogrammetric

Engineering and Remote Sensing. 57: 195–202, Loveland, T.R.; Merchant, J.W.; Ohlen, D.O.; Brown, J.F. 1991. Development of landcover characteristics database for the conterminous U.S. Photogrammetric Engineering and Remote Sensing. 57: 1453–1463, Foody,

G.M.; Campbell, N.A.; Trodd, N.M.; Wood, T.F. 1992. Derivation and applications of probabilistic measures of class membership from

the maximum-likelihood classification. Photogrammetric Engineering and Remote Sensing. 58: 1335–1341, Brown, J.F.; Loveland, T.R.;

Merchant, J.W.; Reed, B.C.; Ohlen, D.O. 1993. Using multisource data in global land-cover characterization: concepts, requirements,

and methods. Photogrammetric Engineering and Remote Sensing. 59: 977–987, Nemani, R.; Pierce, L.; Running, S.; Goward, S. 1993.

Developing satellite-derived estimates of surface moisture status. Journal of Applied Meteorology. 32: 548–557, Samson, S.A. 1993.

Two indices to characterize temporal patterns in the spectral response of vegetation. Photogrammetric Engineering and Remote Sensing.

59: 511–517, Bauer, M.E.; Burk, T.E.; Ek, A.R.; et al. 1994. Satellite inventory of Minnesota forest resources. Photogrammetric

Engineering and Remote Sensing. 60: 287–298, Collins, J.B.; Woodcock, C.E. 1994. Change detection using the Gramm-Schmidt transformation applied to mapping forest mortality. Remote Sensing of Environment. 50: 267–279, Coppin, P.R.; Bauer, M.E. 1994.

Processing of multitemporal Landsat TM imagery to optimize extraction of forest cover change features. IEEE Geoscience and Remote

Sensing. 60: 287–298, Green, K.; Kempka, D.; Lackey, L. 1994. Using remote sensing to detect and monitor land-cover and land-use

change. Photogrammetric Engineering and Remote Sensing. 60: 331–337, Woodcock, C.E.; Macomber, S.; Ryherd, S.; et al. 1994.

Mapping forest vegetation using Landsat TM imagery and a canopy reflectance model. Remote Sensing of Environment. 50: 240–254,

Collins, J.B.; Woodcock, C.E. 1996. An assessment of several linear change detection techniques for mapping forest mortality using

multitemporal Landsat TM data. Remote Sensing of Environment. 56: 66–77, Foody, G.M. 1996. Relating the land-cover composition

of mixed pixels to artificial neural network classification output. Photogrammetric Engineering and Remote Sensing. 62: 491–499, Gao,

B.C. 1996. NDWI—a normalized difference water index for remote sensing of vegetation liquid water from space. Remote Sensing of

Environment. 58: 257–266, Lambin, E.F.; Ehrlich, D. 1996. The surface temperature vegetation index space for land cover and landcover change analysis. International Journal of Remote Sensing. 17: 463–487, White, J.D.; Ryan, K.C.; Key, C.C.; Running, S.W. 1996.

Remote sensing of forest fire severity and vegetation recovery. International Journal of Wildland Fire. 6: 125–136, Fassnacht, K.S.;

Gower, S.T.; MacKenzie, M.D.; Nordheim, E.V.; Lillesand, T.M. 1997. Estimating the leaf area index of north central Wisconsin forests

using the Landsat thematic mapper. Remote Sensing of Environment. 61: 229–245, Johnston, J.J.; Weigel, D.R.; Randolph, J.C. 1997.

Satellite remote sensing: an inexpensive tool for pine plantation management. Journal of Forestry. 95: 16–20, White, J. D.; Running,

S.W.; Nemani, R.; Keane, R.E.; Ryan, K.C. 1997. Measurement and remote sensing of LAI in Rocky Mountain montane ecosystems.

Canadian Journal of Forest Research. 27: 1714–1727, Asner et al. 1998, Carlotto, M.J. 1998. Spectral shape classification of Landsat

thematic mapper imagery. Photogrammetric Engineering and Remote Sensing. 64: 905–913, Chalifoux, S.; Cavayas, F.; Gray, J.T. 1998.

Map-guided approach for the automatic detection on Landsat TM images of forest stands damaged by the spruce budworm.

Photogrammetric Engineering and Remote Sensing. 64: 629–635, Cohen, W.B.; Florella, M.; Gray, J.; Helmer, E.; Anderson, K. 1998.

An efficient and accurate method for mapping forest clearcuts in the Pacific Northwest using Landsat imagery. Photogrammetric

Engineering and Remote Sensing. 64: 293–300, Deppe, F. 1998. Forest area estimation using sample surveys and Landsat MSS and TM

data. Photogrammetric Engineering and Remote. Sensing. 64: 285–292, Mickelson, J.G.; Civco, D.L.; Silander, Jr., J.A. 1998.

Delineating forest canopy species in the northeastern United States using multi-temporal TM imagery. Photogrammetric Engineering

and Remote Sensing. 64: 891–904, and Todd, S.W.; Hoffer, R.M. 1998. Responses of spectral indices to variation in vegetation cover

and soil background. Photogrammetric Engineering and Remote Sensing. 64: 915–921.
Existing Vegetation Classification & Mapping Technical Guide 3-45

• Image texture refers to the apparent roughness and smoothness of an image region

created by the frequency of tonal change on the image. Texture is typically caused

by the pattern of highlighted and shadowed areas as an irregular surface is illuminated

from an oblique angle. Tonal change among groups of pixels would be analogous.

For more information, refer to remote sensing literature that relates primarily to this

element.5 

• Shadow is especially an important clue in the interpretation of objects. Shadows of

buildings, trees, and other objects reveal characteristics that are not obvious from the

overhead view alone. Edges, such as forest boundaries, often have characteristic shadows.

• Pattern refers to the arrangement of individual objects into distinctive, recurring

forms that permit recognition. The distinctive pattern of an orchard, baseball diamond,

or drive-in theater makes them identifiable. A recurring pattern between adjacent

pixels can be used as one of the features of a contextual classification of digital

imagery. For more information, refer to remote sensing literature that relates primarily

to this element. 

• Association specifies characteristic occurrence of certain objects or features, usually

without the strict spatial arrangement implied by pattern. The identification of a

baseball diamond, for instance, is often associated with a school or park.

• Shape refers to the general form, configuration, or outline of individual objects. For

example, lakes, rivers, timber harvest units, and center pivot irrigation fields all have

shapes that can provide clear identification.

• Size of an object or feature is considered in relation to other objects on the image

and to the photo scale.

5 Haralick, R.M.; Shanmugam, K.; Dinsteim, L.H. 1973. Textural features for image classification. IEEE Transactions on systems, man,

and cybernetics. SMC-3: 610–621, Vilnrotter, F.M.; Nevatia, R.; Price, K.E. 1986. Structural analysis of natural textures. IEEE

Transactions on Pattern Analysis and Machine Intelligence. 8: 76–89, Nellis and Briggs 1989, Franklin, S.E.; Peddle, D.R. 1990.

Classification of SPOT HRV imagery and texture features. International Journal of Remote Sensing 11: 551–556, Marceau, D.J.;

Howarth, P.J.; Dubois, J.M.M.; Gratton, D.J. 1990. Evaluation of the grey-level co-occurrence matrix method for land-cover classification

using SPOT imagery. IEEE Transactions on Geoscience and Remote Sensing. 28: 513–519, Peddle, D.R.; Franklin, S.E. 1991. Image

texture processing and data integration for surface pattern discrimination. Photogrammetric Engineering and Remote Sensing. 57:

413–420, Cohen, W.B.; Spies, T.A. 1992. Estimating structural attributes of Douglas-fir/western hemlock forest stands from Landsat

and SPOT imagery. Remote Sensing of Environment. 41: 1–17, Gong, P.; Marceau, D.J.; Howarth, P.J. 1992. A comparison of spatial

feature extraction algorithms for land-use classification with SPOT HRV data. Remote Sensing of Environment. 40: 137–151,

Kushwaha, S.P.S.; Kuntz, S.; Oesten, G. 1994. Applications of image texture in forest classification. International Journal of Remote

Sensing. 15: 2273–2284, Cohen, W.B; Spies, T.A.; Fiorella, M. 1995. Estimating the age and structure of forests in a multi-ownership

landscape of western Oregon, U.S.A. International Journal of Remote Sensing. 16: 721–746, Dikshit, O.; Roy, D.P. 1996. An empirical

investigation of image resampling effects upon the spectral and textural supervised classification of a high spatial resolution multispectral image. Photogrammetric Engineering and Remote Sensing. 62: 1085–1092, Hay, G.J.; Niemann, K.O.; McLean, G.F. 1996. An

object-specific image-texture analysis of H-resolution forest imagery. Remote Sensing of Environment. 55: 108–122, Ricotta, C.;

Avena, G.C.; Ferri, F. 1996. Analysis of human impact on a forested landscape of central Italy with a simplified NDVI texture descriptor.

International Journal of Remote Sensing. 17: 2869–2874, Ryherd and Woodcock 1996, Wulder, M.A.; Franklin, S.E.; Lavigne, M.B.

1996. High spatial resolution optical image texture for improved estimation of forest stand leaf area index. Canadian Journal of Remote

Sensing. 22: 441–449, Jakubauskas, M.E. 1997. Effects of forest succession on texture in Landsat thematic mapper imagery. Canadian

Journal of Remote Sensing. 23: 257–263, Wulder, M.A.; LeDrew, E.F.; Franklin, S.E.; Lavigne, M.B. 1998. Aerial image texture information in the estimation of northern deciduous and mixed wood forest leaf area index (LAI). Remote Sensing of Environment. 64:

64–76, Bian, L.; Butler, R. 1999. Comparing effects of aggregation methods on statistical and spatial properties of simulated spatial

data. Photogrammetric Engineering and Remote Sensing. 65: 73–84, and Emerson, C.W.; N. S.N. LamQuattrochi D.A. 1999. Multi-scale

fractal analysis of image texture and pattern. Photogrammetric Engineering and Remote Sensing. 65: 51–61.
3-46 Existing Vegetation Classification & Mapping Technical Guide

• Site refers to the topographic position, geographic location, or other biophysical

environment factors; e.g., streams and rivers are positioned in valley floors and

lookout towers are positioned on mountaintops or ridges. Other features occur only

in some geographic locations, such as palm trees. This element could also refer to

site characteristics such as potential vegetation setting. For more information, refer

to remote sensing literature that relates primarily to this element.6 

Image Interpretation for Base Level Mapping. High-resolution image interpretation

completed by skilled interpreters is expected to comprise the basis for base-level vegetation

maps. Extensive field data and validation are anticipated to be incorporated into this

process. Depending on the thematic detail in the classification scheme for any given map

product (i.e., plant associations versus alliances), the image interpretation task will involve

various amounts of field validation sampling. This fieldwork may range from simple

“ground truth” reconnaissance to a formal, two-stage sample design to a complete fielddata based attribution of map delineations. Appendix 3B includes example of a structured

aerial photointerpretation data gathering protocol in operational use in the agency. 

Image/Photointerpretation Tasks

• Classification assigns objects, features, or areas to categories based on their appearance

on the imagery.

• Enumeration refers to listing and counting discrete items visible on an image.

Enumeration reports the numbers of classified items present in a defined area.

• Mensuration focuses on two kinds of measurement: (1) photogrammetry, or distance,

height, volumes, and areas; and (2) photometry, the measurement of image brightness.

• Delineation outlines photomorphic patches or regions as they are observed on

remotely sensed images. These areal units are characterized by specific tones and

textures to identify edges or boundaries between separate areas.

Campbell (1987) describes five general image interpretation strategies that are likely

to be incorporated into the base-level vegetation mapping process. 

1. Using field observations to identify features on the imagery. This strategy has been

employed to greater or lesser degrees by nearly all photointerpreters and provides

6 Hutchinson, C.F. 1982. Techniques for combining Landsat and ancillary data for digital classification improvement. Photogrammetric

Engineering and Remote Sensing. 48: 123–130, Cibula, W.G.; Nyquist, M.O. 1987. Use of topographic and climatological models in a

geographical database to improve Landsat MSS classification for Olympic National Park. Photogrammetric Engineering and Remote

Sensing. 53: 67–75, Janssen, L.L.F.; Jaarsma, M.N.; van der Linden, E.T.M. 1990. Integrating topographic data with remote sensing for

land-cover classification. Photogrammetric Engineering and Remote Sensing. 56: 1503–1506, Bolstad, P.V.; Lillesand, T.M. 1992. Rulebased classification models: flexible integration of satellite imagery and thematic spatial data. Photogrammetric Engineering and

Remote Sensing. 58: 965–971, Franklin, S.E.; Wilson, B.A. 1992. A three-stage classifier for remote sensing of mountain environments.

Photogrammetric Engineering and Remote Sensing. 58: 449–454, Gong, P. 1996. Integrated analysis of spatial data from multiple

sources: using evidential reasoning and artificial neural network techniques for geological mapping. Photogrammetric Engineering and

Remote Sensing. 62: 513–523, Lakowski et al. 1997, Stoms, D.M.; Bueno, M.I.; Davis, F.W. et al. 1998. Map guided classification of

regional land cover with multi-temporal AVHRR data. Photogrammetric Engineering and Remote Sensing. 64: 831–838.
Existing Vegetation Classification & Mapping Technical Guide 3-47

reference or training data for most supervised and unsupervised classifications of

satellite imagery.

2. Direct recognition, the application of the interpreter’s accumulated experience, skill,

and judgment to map features recorded on an image. An example would be the

recognition of a golf course or baseball diamond on aerial photographs.

3. Interpretation by inference, using the visible distribution for a distribution that is

not visible on the image. An example is interpretation of soil patterns, inferred from

vegetation and topography, from aerial photographs. This strategy constitutes the

vast majority of classifications of satellite imagery.

4. Probabilistic interpretation, which typically relies on the relationship between some

element of image interpretation and the probable interpretation. Collateral (nonimage)

information is commonly used in probabilistic interpretation.

5. Deterministic interpretation, where image characteristics and ground conditions are

tied with quantitatively expressed deterministic relationships. A common example is

using stereo photogrammetry to determine the height of an object on the photos.

Image Classification for Mid Level Mapping. Classification of medium-resolution image

data (e.g., Landsat TM) is expected to comprise the basis for mid-level vegetation maps.

These classifications are expected to be objective and repeatable methods that result in

consistent map products. 

Image Classification Task

• Radiometric correction is made for sensor system detectors when the system is not

functioning properly. Radiometric correction is also made for atmospheric attenuation

caused by scattering and absorption in the atmosphere and topographic attenuation.

• Geometric and terrain correction removes systematic and systematic geometric

errors and makes the geometry of the image planimetric.

• Image classification logic and algorithm assign pixels to map units from these four

general categories:

- Unsupervised classification is the identification of natural groups or clusters in 

multispectral data with subsequent information map unit assignment.

- Supervised classification is the process of using samples of known identity (i.e., 

pixels already assigned to information classes) to classify pixels of unknown identity.

- Unsupervised/supervised hybrid classification is the combination of a supervised 

and unsupervised classification.

- Ancillary data hybrid classification is the use of nonimage information with a 

supervised or unsupervised classification.

• Extract data from training (reference) sites selected from representative and relatively

homogeneous land cover classes in the image. Collect spectral statistics for the

modeling units representing each training site.
3-48 Existing Vegetation Classification & Mapping Technical Guide

• Select appropriate bands using feature selection criteria to discriminate between

classes and eliminate redundant information. 

• If required, extract training statistics from final band selection.

• Extract thematic information and assign modeling units to map units or categories.

• Attribute delineated map features with thematic information.

• Correct for anomalous error in thematic information.

• Evaluate classification error using the remote sensing derived classification map

and accuracy assessment (reference) data commonly summarized in an error matrix.

“The overall objective of image classification procedures is to automatically categorize

all pixels in an image into land cover classes or themes....Typically, multispectral data are

used to perform the classification and, indeed, the spectral pattern present within the data

for each pixel is used as the numerical basis for categorization” (Lillesand and Kiefer

2000). Four general analytical strategies exist for classifying digital remote sensing data

into thematic map units or categories that are likely to be incorporated into the mid-level

vegetation mapping process. All these general analytical approaches are often combined

with manual classification of selected classes and/or manual edits of problem areas.

• Unsupervised classification to identify natural, spectral groups or spectral clusters

in multispectral data. These clusters of data have unknown thematic content at the

time they are created. The thematic labels are later assigned to the spectral statistical

groups, often with some grouping or splitting of the original clusters.

• Supervised classification using samples of known identity (i.e., training data or pixels/

regions already assigned to map units or categories) to classify pixels/regions of

unknown identity. The training data establish the statistical relationships that comprise

the basis for information class assignments to the most probable thematic class.

• Unsupervised/supervised hybrid classification. This hybrid approach combines the

strengths of the two approaches and is common in vegetation mapping.

• Ancillary data hybrid classification combining nonimage information with a supervised

and/or unsupervised classification. This strategy often applies ecological models to

constrain the membership in thematic classes, thereby reducing error. An example of

a simple ecological model would be to impose elevation ranges on classes that are not

spectrally distinguishable but easily separated based on their biophysical setting. 

Reference Data

Reference data collection is a vital part of vegetation mapping projects. Reference data is

necessary to successfully complete a mapping project. Emphasize designing the reference

data collection and identifying training and accuracy assessment sites.

Reference data collection refers to the effort expended to collect quantitative or qualitative data about ground features. Although field data collection is not always necessary,
Existing Vegetation Classification & Mapping Technical Guide 3-49

some type of reference data is needed to help interpret and/or assess accuracy during a

mapping project. Reference data are frequently collected on the ground through field visits;

several other techniques, however, are available for collecting this data. For example,

interpreting aerial photographs or observation and taking notes from a helicopter or fixedwing aircraft have been successful techniques for collecting reference data. Recently,

airborne video cameras have been used. Data collection techniques depend on the level

of detail needed to satisfy the requirements of the particular mapping project (Congalton

and Biging 1992).

In remote sensing projects, reference data serve two primary purposes. First, reference

data establish a link between variation on the ground and in the image. This link is necessary for assigning image modeling units (pixels or regions) to discrete land cover classes

in the image classification process. Second, reference data help assess a map’s accuracy.

Training data are representative areas of land cover that are identified on the satellite

image and in the reference data source. In effect, training data are used to “train” the

computer to assign information to a particular modeling unit. For example, a computer

classification may separate a lake and a meadow on a satellite image based on spectral

differences. The computer, however, will not be able to label lakes and meadows correctly

until the appropriate reference information is supplied.

Accuracy assessment data, like training data, are samples of land cover and vegetation

identified on the satellite image (classified image) and in the reference data source.

Although training data are used in the image classification process, accuracy assessment

data are used after the classification is completed to assess the accuracy of the final map.

The accuracy of a classification is the degree to which the map’s identification of various

objects on the ground can be corroborated by the accuracy assessment data. For most

projects, the same type of data is collected for training and accuracy data.

The most common sources of reference data for remote sensing projects are aerial

photointerpretation and field data collection. Remote sensing projects commonly use photointerpretation as a primary source of reference data or to combine these two sources.

Numerous references illustrate the development and use of reference data.7 Many of these

studies used photointerpretation in conjunction with field sampling; many others relied

exclusively on the photointerpretation to provide these reference data.

7 Strahler, A.H. 1980. The use of prior probabilities in maximum likelihood classification of remotely sensed data. Remote Sensing of

Environment. 10: 135–163, Shasby, M.; Carneggie, D. 1986. Vegetation and terrain mapping in Alaska using Landsat MSS and digital

terrain data. Photogrammetric Engineering and Remote Sensing. 52: 779–786, Cibula, W.G.; Nyquist, M.O. 1987. Use of topographic

and climatological models in a geographical database to improve Landsat MSS classification for Olympic National Park.

Photogrammetric Engineering and Remote Sensing. 53: 67–75, Fung, T.; LeDrew, E. 1987. Application of principal components analysis

to change detection. Photogrammetric Engineering and Remote Sensing. 53: 1649–1658, Chuvieco and Congalton 1988, Leprieur, C.E.;

Durand, J.M. 1988. Influence of topography on forest reflectance using Landsat thematic mapper and digital terrain data. Photogrammetric

Engineering and Remote Sensing. 54: 491–496, Franklin, S.E.; D.R. Peddle. 1990. Classification of SPOT HRV imagery and texture

features. International Journal of Remote Sensing 11: 551–556, Janssen, L.L.F.; Jaarsma, M.N.; van der Linden, E.T.M. 1990. Integrating

topographic data with remote sensing for land-cover classification. Photogrammetric Engineering and Remote Sensing. 56: 1503–1506,

Marceau, D.J.; Howarth, P.J.; Dubois, J.M.M.; Gratton, D.J. 1990. Evaluation of the grey-level co-occurrence matrix method for land-cover
3-50 Existing Vegetation Classification & Mapping Technical Guide

Independent of the source of reference data, promoting consistency between the training

and accuracy assessment data is important. Training and accuracy assessment data should be

of similar type and follow the taxonomic logic and data standards. For most projects, the

same type of data is collected for training and accuracy assessment applications.

Thematic Map Accuracy Assessment

Accuracy assessments are essential parts of all remote sensing projects. First, they

enable the user to compare different methods and sensors. Second, they provide information on the reliability and usefulness of remote sensing techniques for a particular

application. Finally, and most importantly, accuracy assessments support the spatial data

used in decisionmaking processes. Too often, vegetation and other maps are used without a clear understanding of their reliability. A false sense of security about the accuracy

of the map may result in an inappropriate use of the map; important management decisions may be made on data with unknown and/or unreliable accuracy. Although quantitative accuracy assessment can be time consuming and expensive, it must be an integral

part of any vegetation mapping project.

Quantitative accuracy assessment depends on the collection of reference data.

Reference data is known information of high accuracy (theoretically 100-percent accuracy) about a specific area on the ground (the accuracy assessment site). The assumed-true

reference data can be obtained from ground visits, photointerpretations, video interpretations, or some combination of these methods. In a digital map, accuracy assessment sites

are generally the same type of modeling unit used to create the map. Accuracy assessment

involves the comparison of the categorized data for these sites (i.e., modeling units) to the

reference data for the same sites. The error matrix is the standard way of presenting results

classification using SPOT imagery. IEEE Transactions on Geoscience and Remote Sensing. 28: 513–519, Cetin and Levandowski 1991,

Loveland, T.R.; Merchant, J.W.; Ohlen, D.O.; Brown, J.F. 1991. Development of land-cover characteristics database for the conterminous

U.S. Photogrammetric Engineering and Remote Sensing. 57: 1453–1463, Peddle, D.R.; Franklin, S.E. 1991. Image texture processing

and data integration for surface pattern discrimination. Photogrammetric Engineering and Remote Sensing. 57: 413–420, Bolstad and

Lillesand 1992, Foody, G.M.; Campbell, N.A.; Trodd, N.M.; Wood, T.F. 1992. Derivation and applications of probabilistic measures of

class membership from the maximum-likelihood classification. Photogrammetric Engineering and Remote Sensing. 58: 1335–1341,

Gong and Howarth 1992, Gong, P.; Marceau, D.J.; Howarth, P.J. 1992. A comparison of spatial feature extraction algorithms for land-use

classification with SPOT HRV data. Remote Sensing of Environment. 40: 137–151, Bauer et al. 1994, Coppin, P.R.; Bauer, M.E. 1994.

Processing of multitemporal Landsat TM imagery to optimize extraction of forest cover change features. IEEE Geoscience and Remote

Sensing. 60: 287–298, Green, K.; Kempka, D.; Lackey, L. 1994. Using remote sensing to detect and monitor land-cover and land-use

change. Photogrammetric Engineering and Remote Sensing. 60: 331–337, Woodcock, C.E.; Macomber, S.; Ryherd, S.; et al. 1994.

Mapping forest vegetation using Landsat TM imagery and a canopy reflectance model. Remote Sensing of Environment. 50: 240–254,

Cohen, W.B; Spies, T.A.; Fiorella, M. 1995. Estimating the age and structure of forests in a multi-ownership landscape of western Oregon,

U.S.A. International Journal of Remote Sensing. 16: 721–746, Dikshit, O.; Roy, D.P. 1996. An empirical investigation of image resampling

effects upon the spectral and textural supervised classification of a high spatial resolution multispectral image. Photogrammetric

Engineering and Remote Sensing. 62: 1085–1092, Shandley, J.; Franklin, J.; White, T. 1996. Testing the Woodcock-Harward image segmentation algorithm in an area of southern California chaparral and woodland vegetation. International Journal of Remote Sensing. 17:

983–1004, Jakubauskas, M.E. 1997. Effects of forest succession on texture in Landsat thematic mapper imagery. Canadian Journal of

Remote Sensing. 23: 257–263, Johnston, J.J.; Weigel, D.R.; Randolph, J.C. 1997. Satellite remote sensing: an inexpensive tool for pine

plantation management. Journal of Forestry. 95: 16–20, Cross, A.M.; Mason, D.C.; Dury, S.J. 1988. Segmentation of remotely sensed

images by a split-and-merge process. International Journal of Remote Sensing. 9: 1329–1345, Deppe, F. 1998. Forest area estimation

using sample surveys and Landsat MSS and TM data. Photogrammetric Engineering and Remote. Sensing. 64: 285–292, and Lo, C.P.;

Watson, L.J. 1998. The influence of geographic sampling methods on vegetation map accuracy evaluation in a swampy environment.

Photogrammetric Engineering and Remote Sensing. 64: 1189–1200.
Existing Vegetation Classification & Mapping Technical Guide 3-51

Table 3.22. Error matrix example.

Reference data

Herbaceous/ 

Tree Shrub nonvascular Sparsely 

dominated dominated dominated vegetated Row total

Tree dominated 65 4 22 24 115

Shrub dominated 6 81 5 8 100

Classified Herbaceous/ 

data nonvascular 0 11 85 19 115

dominated

Sparsely vegetated 47 3 90 104

Column total 75 103 115 141 434

Overall Accuracy = 321/434 = 74 percent

Producer’s Accuracy User’s Accuracy 

Tree Dominated = 65/75 = 87 percent Tree Dominated = 65/115 = 57 percent

Shrub Dominated = 81/103 = 79 percent Shrub Dominated = 81/100 = 81 percent

Herbaceous/Nonvascular Dominated = 85/115 = 74 percent Herbaceous/Nonvascular Dominated = 85/115 = 74 percent

Sparsely vegetated = 90/141 = 64 percent Sparsely vegetated = 90/115 = 87 percent

of an accuracy assessment (Story and Congalton 1986). This matrix is a square array in

which accuracy assessment sites are tallied by their classified category in the image and

their actual category according to the reference data (table 3.22). Typically, the rows in the

matrix represent the classified image data, while the columns represent the reference data.

The major diagonal, highlighted in the following table, contains those sites where the classified data agree with the reference data.

The nature of errors in the classified map can also be derived from the error matrix.

In the matrix, errors (the off-diagonal elements) are errors of inclusion (commission

errors) or errors of exclusion (omission errors). Commission errors appear in the offdiagonal matrix cells that form the horizontal row for a particular class. Omission error

is represented in the off-diagonal vertical row cells. High errors of omission/commission

between two or more classes indicate spectral confusion between these classes.

Useful measures of accuracy are easily derived from the error matrix:

• Overall accuracy, a common measure of accuracy, is computed by dividing the total

correct samples (the diagonal elements) by the total number of assessment sites

found in the bottom right cell of the matrix.

• Producer’s accuracy, based on omission error, is the probability of a reference site

being correctly classified. Producer’s accuracy is calculated by dividing the total

number of correct accuracy sites for a class (diagonal elements) by the total number

of reference sites for that class located in the bottom cell in each column.

• User’s accuracy, which is based on commission error, is the probability that a pixel on

the map actually represents that category on the ground. User’s accuracy is calculated
3-52 Existing Vegetation Classification & Mapping Technical Guide

by dividing the number of correct accuracy sites for a category by the total number

of accuracy assessment sites, located in the far right cell of each row, that were

classified in that category (Story and Congalton 1986).

Conducting an accuracy assessment is a multistep process whose successful completion requires a number of decisions and an awareness of the challenges previously

described. Following are the general steps in accuracy assessment:

Step 1: Develop the sampling scheme. Many opinions exist on the proper sampling design

to use with digital image classification. In most situations, random sampling (simple

random or systematic random) without replacement and stratified random sampling will

provide satisfactory results (see the discussion in Congalton 1991 and Stehman 1992).

Random sampling often is not practical in the field, and stratified sampling requires collection of the accuracy assessment sites after the classification has been completed, which

requires a second field effort. When photointerpretation is the primary reference data

source, these limitations no longer apply. Regardless of the specific approach, all sampling

schemes should contain an element of randomness to help eliminate interpreter’s bias.

The appropriate sample number and size are other important considerations. The

number of sample sites must be large enough to be statistically sound but not larger than

necessary for the sake of efficiency. If overall accuracy is to be considered, more samples will be needed to examine the nature of errors in individual categories (the offdiagonal elements in the error matrix). A general rule of thumb is that at least 20 sites

are required for each category in the classification. Congalton (1991) suggests 50 sites

for each category and 75 to 100 sites per map unit for large areas with many categories.

Evaluating the frequency distribution of class membership by attribute can make an estimate of the appropriate sample size.

The need for statistical validity must be balanced with practical considerations, such

as time and budget constraints. Documentation should include an explanation of any statistical compromises made. Accuracy assessment sites are expensive and time consuming

to delineate, characterize, and ground check. In determining the number of accuracy

assessment sites to investigate, a tactical approach is recommended. Categories of particular

importance may warrant more sites while relatively less important or easily mappable

categories, such as snow and open water, may need fewer sites. Additionally, the proportion

of field-visited to photointerpreted sites can be adjusted to balance statistical and practical

considerations. For example, more photo sites may be collected than ground sites, and

the ground-visited sites may be selected partly because of their accessibility.
Existing Vegetation Classification & Mapping Technical Guide 3-53

Step 2: Choose the appropriate reference data. Reference data may be an existing map,

existing resource inventory data, photointerpreted accuracy sites, or data collected on

the ground. Because a major assumption in quantitative accuracy assessment is that the

reference data are 100-percent correct, every effort should be made to secure the highest

quality reference data. The analyst should be aware that, in many cases, reliable maps

do not exist and inventory data are out of date. Often the available data are in a form that

is incompatible with the classification scheme. To provide anything other than qualitative

information, reference data must conform to the same classification scheme as the

classified data. 

Using photointerpretations as reference data requires taking special care.

Photointerpreted sites have traditionally been accepted as 100-percent correct when

used to assess the accuracy of digital classifications; however, as Biging and Congalton

(1989) observed, perfect accuracy is rarely attributable to photointerpretations. To help

minimize errors, apply the following principles: the date of the photos should be close to

the date of the digital imagery; experienced interpreters familiar with both the vegetation

and the classification scheme must conduct photointerpretations of accuracy sites; and

to ensure the accuracy and consistency of the reference data, photointerpretations should

be closely inspected.

Using precise ground measurements and/or photointerpretations as reference data is

a frequent method of assessing the accuracy of the classified image. To minimize costs

and maximize efficiency, data from accuracy assessment sites can be collected during

the same field visit for collecting training site data. Accuracy assessment sites cannot be

used as training sites. Additional photointerpreted sites can be collected after the field

season, when the photointerpreters have experience with the project area. This combined

approach can be a cost-effective means of acquiring accurate reference data.

Step 3: Delineate the accuracy assessment sites on the reference data. After the sampling

scheme, sample size, and reference data are determined, the accuracy sites can be delineated. Because pinpointing the location is critical to determining the accuracy of the

classified image, all assessment site locations must be precisely delineated on base maps,

orthophotos, resource photographs, or collected with a global positioning system (GPS).

For large projects, developing and maintaining a relational database is an efficient way

of organizing and working with accuracy assessment data. Typically, accuracy assessment

sites are delineated on resource photographs. Sites should be homogeneous with regard

to map category and/or modeling unit (e.g., homogeneous crown closure class or homogeneous species mix). Unambiguous delineation rules must be established. Of utmost

importance is that the sampling procedure be unbiased.
3-54 Existing Vegetation Classification & Mapping Technical Guide

Step 4: Interpret the assessment sites from the reference data. As mentioned in step 2,

accuracy assessment data must conform to the same classification scheme as the data used

to produce the map. This is true regardless of whether field-verified or photointerpreted

sites are used. The same labeling rules (classification key) used to assign labels to features

in the map must be used to label accuracy assessment sites. To eliminate bias, the person

collecting the reference data should be very familiar with the classification scheme, but

not with the classified map. This person should have no prior knowledge of the map label

for the corresponding accuracy assessment sites.

Step 5: Compile the classified data for accuracy assessment sites. Accuracy sites must

be precisely located on the classified image or map coverage. Accuracy sites delineated

on resource photography can be digitized directly over the satellite imagery or digital

orthophotos. Sites with GPS data can be digitally transferred to the GIS. When crossreferencing the vegetation map with the accuracy assessment data, the accuracy assessment

site may overlap more that one map feature. When this occurs, determine if the reference

site data can be subdivided to follow map feature boundaries. The spatial accuracy of

the reference data relative to the spatial accuracy of the map features must be considered.

If the reference site data cannot be confidently assigned to one or more map features, it

should not be used to for map accuracy. The goal is to develop a label for the accuracy

assessment site to compare with the map feature label corresponding to the location of

the reference site.

Step 6: Perform quality control. Although quality control is listed as a separate task, in

practice it is an ongoing and iterative process. Errors in accuracy assessments will appear

as errors in the classification, thereby resulting in an underestimation of the classification’s

accuracy. Some common errors include data entry mistakes, incomplete accuracy

assessment forms, incorrect location of accuracy sites, incorrect interpretation of the

accuracy site, and accuracy sites not entered into the database or missing from analysis.

Step 7: Build the error matrix. Tallying each accuracy site according to its accuracy

assessment label and classification label creates the error matrix. Many commercial

image-processing systems provide modules to create and analyze error matrices.

Step 8: Summarize and present accuracy assessment results. To prevent inappropriate

uses, the error matrix and a discussion and analysis of the accuracy results should

accompany any use of the classified map.

A relatively recent innovation in accuracy assessment is the use of fuzzy sets for

accuracy assessments. Traditional accuracy assessment as described in section suffers

from certain limitations. First, it assumes that each accuracy site can be unambiguously
Existing Vegetation Classification & Mapping Technical Guide 3-55

assigned to a single map category (Gopal and Woodcock 1994) when in reality it may

be part of a continuum between map categories. Second, the traditional error matrix makes

no distinction between magnitudes of error. For example, in a traditional error matrix,

misclassifying “conifer forest” as “open water” carries the same weight as the error of

misclassifying it as “conifer/hardwood mix.”

Fuzzy logic is designed to handle ambiguity and, therefore, should be considered

for an accuracy assessment of complex or potentially ambiguous classification. Instead

of assessing a site as correct/incorrect as in a traditional assessment, an assessment using

fuzzy sets can rate a site as absolutely wrong, understandable but wrong, reasonable or

acceptable match, good match, or absolutely right (Gopal and Woodcock 1994). The

resulting accuracy assessment can then rate the seriousness of errors as well as absolute

correctness/incorrectness. For a complete description of applying fuzzy sets to accuracy

assessment, see Woodcock and Gopal (1992).

3.3 Field and Aerial Photography Data

In this section: Identification of sources for data collection standards, protocols, and forms

The collection and use of field data for map development can be a significant part

of the mapping process. For the purposes of this technical guide, the term “field data”

applies to measurements or direct observations made in the field while collecting reference data or making interim map assessments. These field data can exist in a number of

formats but are typically characterized as plot level data or summary observations of a

geographically specific area. 

Similarly, the collection and use of aerial photography data for map development

can also be a significant part of the mapping process. For the purposes of this technical

guide, the term “aerial photo data” applies to data measured or interpreted from vertical

aerial photography following the image interpretation process outlined in section 3.2.4.

The collection and notation of summary observations for interim map assessment is

inherently a more subjective process, relying more on ocular estimation and interpretation

than on measurement. This type of field data has limited application, but can be efficiently

and cost effectively collected across broad geographic extents and is suitable for collecting

training data and reviewing map products during the development stage. No standards

currently govern the collection and storage of these data, nor is it the intent of this technical

guide to direct their collection and storage. For the purposes of characterizing their utility

and ensuring data consistency, however, section 3.3.5 outlines a field review approach.
3-56 Existing Vegetation Classification & Mapping Technical Guide

3.3.1 Field Data Collection Standards and Methods 

Standards (Common Stand Exam [CSE] Users Guide, V1.6) for the collection of plot level

data for stand exams and vegetation inventories have already been established and are logically applied to data collection for mapping purposes (USDA Forest Service 2004a).

3.3.2 Field Data Forms

Field data forms are often used to record plot level data for stand exams and vegetation

inventory data. These data can also be entered directly into a field data recorder.

3.3.3 Aerial Photo Data Collection Standards and Methods

A variety of aerial photointerpretation protocols have been used throughout the Forest

Service in conjunction with remote sensing projects. Appendix 3B contains an example of an

operational photointerpretation protocol applied to remote sensing reference data collection.

3.3.4 Aerial Photo Data Forms

Aerial photo data forms are often used to record data from photointerpretation. These

data can also be entered directly into an electronic database or spreadsheet.

3.3.5 Field Reviews 

Field reviews conducted for map assessment during the mapping process generally

entail summarizing the vegetation composition and structure in a geographically specific

manner. Often, notations about whether the map accurately characterizes or mislabels the

vegetation are also included. This information is then used to refine systematic mapping

processes (image classifications and ecological modeling rules) and edit map attributes

for anomalous errors. 

Collecting an adequate amount of information requires extensive review of the project

area. In large project areas associated with the mid, broad, and national levels, this is

usually a rapid assessment process requiring vehicle or aircraft travel. Base-level mapping projects may require walkthrough observations.

The interim map products are taken into the field as printed maps or a digital product

on a laptop computer. Notes are taken about specific features in the map, noting the

composition and structure. Correct map attributes can also be recorded but generally have

less utility than basic data that can be categorized into multiple systems. Field review

vegetation maps are more easily used when they include road systems, hydrography, and

terrain characteristics. U.S. Geological Survey 7.5-minute base series maps can serve as

an effective overlay on vegetation draft maps to provide this ancillary information. 
Existing Vegetation Classification & Mapping Technical Guide 3-57

3.4 Metadata/Documentation

Metadata have been established as a standard part of a final vegetation map product. The

FGDC requires that metadata accompany digital map products; therefore, this technical

guide provides metadata standards for existing vegetation maps. Metadata protocols

contained herein are taken directly from the FGDC documents detailing the content and

format of digital geospatial data.

3.4.1 Metadata Entry Methods and Verification 

In this section: FGDC metadata requirements for vegetation maps

3.4.1.1 Metadata Required for Existing Vegetation Maps

FGDC Metadata Standards

Metadata or “data about data” describe the content, quality, condition, and other characteristics of data. The FGDC approved the Content Standard for Digital Geospatial

Metadata (FGDC-STD-001) in June 1998.

Objective. The objective of the FGDC metadata standards is to provide a common set

of terminology and definitions for the documentation of digital geospatial data. Other

requirements specific to vegetation classification and mapping are provided in the

FGDC-approved Vegetation Classification Standard (FGDC-STD-005) in June 1997.

Scope. Executive Order No. 12906, Coordinating Geographic Data Acquisition and Access:

The National Spatial Data Infrastructure, was signed on April 11, 1994. Section 3,

Development of a National Geospatial Data Clearinghouse, paragraph (b) states that

“each agency shall document all new geospatial data it collects or produces, either

directly or indirectly, using the standard under development by the FGDC, and make that

standardized documentation electronically accessible to the Clearinghouse network.”

The standard was developed from the perspective of defining the information

required by a prospective user to determine the availability of a set of geospatial data,

the fitness of the set of geospatial data for an intended use, the means to access the set of

geospatial data, and to successfully transfer the set of geospatial data. Thus, the standard

establishes the names of data elements and compound elements to be used for these purposes, the definitions of these data elements and compound elements, and information

about the values that are to be provided for the data elements. The standard does not

specify how this information is to be organized in a computer system or data transfer, or

to transmit, communicate, or present this information to the user. Content Standard for

Digital Geospatial Metadata, CSDGM Version 2—FGDC-STD-001-1998, on the FGDC

website provides detailed instructions on developing FGDC metadata.
3-58 Existing Vegetation Classification & Mapping Technical Guide

For a general interview approach for creating metadata, see appendix 3D. Appendix

3E contains a standard metadata template.

3.4.1.2 Specific Metadata Requirements in the FGDC Vegetation

Classification Standard

“Agencies should record and make available the required FGDC metadata during the

course of vegetation inventory, whether data has been gathered via remote sensing or

fieldwork.” This FGDC metadata includes but is not limited to the following items:

• Metadata for field (stand and plot) samples:

- Data collectors: name and affiliation of investigators.

- Date of fieldwork.

- Field methods: plot design, date of observation/data collection, date of classification.

• Geographic coordinates:

- Universal Transverse Mercator (UTM) or latitude/longitude coordinates of sample.

- The data—North American Datum of 1927 (NAD27) or 1983 (NAD83).

- Method of determination and estimation of location accuracy information in the 

form of ± X meters.

• Sampling design: 

- How, why, and how many sample sites were chosen (e.g., subjective, random, 

stratified).

- Approximate extent of the stand sampled.

- Where and how the data are stored.

• Metadata for remotely sensed samples:

- Type of imagery (TM, SPOT, aircraft scanner, radar, CIR (color infrared), BW 

(panchromatic), video).

- Source—mono, stereo, vertical, oblique.

- Scale or resolution of imagery.

- Date of imagery.

- Methods used to classify type.

- Method of imagery classification (visual or computer assisted).

- Geographic coordinates (UTM or latitude/longitude coordinates) of samples:

~ The datum—NAD27 or NAD83.

~ Method of determination and estimation of location accuracy information in the

form of ± X meters. 
Existing Vegetation Classification & Mapping Technical Guide 3-59

3.4.2 Database Structure Overview

In this section: Reference to the corporate database structure for existing vegetation 

geospatial datasets

Vegetation map products will be stored and maintained as geospatial databases containing

the standard vegetation attributes, regional and local add-on attributes, and internal GIS

database fields. Appendix 3F specifies the location and definition of standard and coreoptional data fields required for existing vegetation map product. Valid values tables for

the required fields are also included in appendix 3F.

3.4.3 Data Management 

In this section: Strategy for keeping vegetation maps current and applicable to monitoring

3.4.3.1 Maintain Existing Vegetation Maps

Baseline Establishment

Critical to planning, inventory, and monitoring success is the establishment of consistent

vegetation baseline information. Once established, vegetation changes and their causes

can be determined. This information provides monitoring data to analyze the effects of

change in condition of wildlife habitats, late successional old growth, forest health,

mortality, growth, and standing forest volumes. Vegetation maps, when combined with

ground-based inventory information, are fundamental to meet the needs of the Forest and

Rangeland Resources Planning Act, Forest Resource Management Plans, bioregional

assessments, and more localized watershed and project planning efforts.

Scheduling Updates

The goal for vegetation resource information is to have vegetation maps no more than

5 years old. Update map areas where changes to vegetation have occurred from various

causes, such as regrowth, wildfire, harvest, insect and disease damage, vegetation treatments, agriculture, or built-out type conversions. Activity databases and change detection

methods are helpful in identifying where updates need to occur and the causes of vegetation

cover changes.

Coordinating Related Work Activities

When programming mapping or updating vegetation maps work, coordinate a schedule

with others to acquire resource photography, satellite imagery, and vegetation resource

information. Other work programs, such as surface fuels mapping, ground based inventory,

and change detection monitoring programs, can be coordinated with vegetation mapping.

Coordinating aerial photos and imagery acquisition contributes to the efficiency of all

these efforts.
3-60 Existing Vegetation Classification & Mapping Technical Guide

When developing a multiyear coordinated schedule for a region, consider using physiographic and administrative provinces, national forest acreages, current status of vegetation

mapping, change detection, Forest Inventory Analysis (FIA) grid inventories, and land and

resource management plan revision schedules. At the beginning of the cycle for an update

area, plan to acquire aerial photography and imagery the summer before starting any mapping or change detection efforts. Next, schedule vegetation map updates and forest inventory remeasurements of changed areas. Finally, conduct trend analysis and monitoring by

comparing baseline and update information. Yearly budgets need to be stable to keep scheduled activities on cycle. Programs can realize major cost savings only when current photos

and imagery can be substituted for ground-based visits through interpretation. To achieve a

coordinated cycle, baseline vegetation maps and FIA grid inventory plots need to be completed to a common standard and source dates in a province as much as possible, balancing

workloads and budget constraints. By establishing a systematic update cycle for mapping

and inventory, opportunities for partnerships outside of the national forests become more

available with State and Federal agencies.

Tracking Changes Over Time

To understand vegetation changes on the landscape and its affect on related natural

resources, track changes and their causes to compare with baseline inventories. Tracking

imagery sources and dates of baseline maps as well as updating imagery sources and dates

are necessary metadata. Cause of change is also important to know and aids in analysis

of impacted resources, such as wildlife habitat and cumulative watershed impacts.
Existing Vegetation Classification & Mapping Technical Guide 4-1

Literature Cited

Abercrombie, M.; Hickman, C.J.; Johnson, M.L. 1966. A dictionary of biology. Baltimore, MD:

Penguin Books.

Allaby, M. 1994. The concise Oxford dictionary of ecology. Oxford, UK: Oxford University Press.

Anderson, J.R.; Hardy, E.E.; Roach, J.T.; Witmer, R.E. 1976. A land use and land cover classification system for use with remote sensor data. U.S. Department of Interior, Geological Survey

Professional Paper 964. Washington, DC: U.S. Government Printing Office.

Anderson, M.; Bourgeron, P.; Bryer, M.T.; et al. 1998. International classification of ecological

communities: terrestrial vegetation of the United States. Arlington, VA: The Nature Conservancy.

Vol. 2: The national vegetation classification system: list of types.

Asner, G.P.; Wessman, C.A.; Schimel, D.S.; Archer, S. 1998. Variability in leaf and litter optical

properties: implications for BRDF model inversions using AVHRR, MODIS, and MISR. Remote

Sensing of Environment. 63: 243–257.

Austin, M. P.; Heyligers, P.C. 1991. New approach to vegetation survey design: gradsect sampling.

In: Margules, C.R.; Austin, M.P., eds. Nature conservation: cost-effective biological surveys and

data analysis. Melbourne, Australia: Commonwealth Scientific and Industrial Research

Organization: 31–36.

Avery, T.E. 1977. Interpretation of aerial photographs. Minneapolis, MN: Burgess.

Bailey, R.G. 1980. Description of the ecoregions of the United States. Misc. Pub. 1391.

Washington, DC: U.S. Department of Agriculture, Forest Service.

Bailey, R.G.; Jensen, M.E.; Cleland, D.T.; Bourgeron, P.S. 1994. Design and use of ecological

mapping units. In: Jensen, M.E.; Bourgeron, P.S., eds. Eastside forest ecosystem health assessment.

Gen. Tech. Rep. PNW-GTR-318. Portland, OR: U.S. Department of Agriculture, Forest Service.

Vol. 2: Ecosystem management: principles and applications: 95–106.

Barbour, M.G.; Burk, J.H.; Pitts, W.D. 1980. Terrestrial plant ecology. Menlo Park, CA:

Benjamin/Cummings.

Biging, G.; Congalton, R.G. 1989. Advances in forest inventory using digital imagery. In:

Proceedings, global natural research monitoring and assessments: preparing for the 21st century.

Venice, Italy: [Publisher unknown]: 3: 1241–1249.

Boice, J.M. 1998. Genesis: an expositional commentary. Grand Rapids, MI: Baker Books. Vol. 1.

Bourgeron, P.S.; Humphries, H.C.; DeVelice, R.L.; Jensen, M.E. 1994. Ecological theory in

relation to landscape and ecosystem characterization. In: Jensen, M.E.; Bourgeron, P.S., eds.

Eastside forest ecosystem health assessment. Gen. Tech. Rep. PNW-GTR-318. Portland, OR:

U.S. Department of Agriculture, Forest Service. Vol. 2: Ecosystem management: principles and

applications: 58–72.
4-2 Existing Vegetation Classification & Mapping Technical Guide

Brackney, E.S.; Jennings, M.D., eds. 1998. Gap Analysis Bulletin 7. U.S. Geological Survey

Biological Resources Division Gap Analysis Program, Moscow, ID: U.S. Geological Survey,

Biological Resources Division.

Braun-Blanquet, J. 1932. Plant sociology: the study of plant communities., New York: McGraw-Hill.

Brown, D.E.; Lowe, C.H.; Pase, C.P. 1980. A digitized systematic classification for ecosystems

with an illustrated summary of the natural vegetation of North America. Gen. Tech. Rep. RM-73.

[Place of publication unknown]: U.S. Department of Agriculture, Forest Service.

Buol, S.W.; Hole, F.D.; McCracken, R.J. 1973. Soil genesis and classification. Ames, IA: The

Iowa State University Press.

Burrough, P.A. 1986. Principles of geographical information systems for land resource assessment.

New York: Oxford University Press.

Campbell, J.B. 1987. Introduction to remote sensing. New York: Guilford Press.

Chuvieco, E.; Congalton, R.G. 1988. Using cluster analysis to improve the selection of training

statistics in classifying remotely sensed data. Photogrammetric Engineering and Remote Sensing.

54: 1275–1281.

Clarke, K.C. 1999. Getting started with geographic information systems. 2nd ed. Upper Saddle

River, NJ: Prentice-Hall.

Clinton, W.L. 1994. Coordinating geographic data acquisition and access: the national spatial

data infrastructure (Executive Order 12906). Federal Register 59: 17671–17674.

http://www.fgdc.gov/publications/documents/geninfo/execord.html. [Date accessed unknown].

Collinson, A.S. 1988. Introduction to world vegetation. 2nd ed. London, UK: Unwin Hyman.

Congalton, R.G. 1991. A review of assessing the accuracy of classification of remotely sensed

data. Remote Sensing of the Environment. 37: 35–46.

Congalton, R.G.; Biging, G. 1992. A pilot study evaluating ground reference data collection

efforts for use in forest inventory. Photogrammetric Engineering and Remote Sensing. 58:

1669–1671.

Cowardin, L.M.; Carter, V.; Golet, F.C.; LaRoe, E.T. 1979. Classification of wetlands and deepwater habitats of the United States. FWS/OBS-79/31. Corvallis, OR: U.S. Department of Interior,

Fish and Wildlife Service Biological Services Program.

Cullinan, V.I.; Thomas, J.M. 1992. A comparison of quantitative methods for examining landscape pattern and scale. Landscape Ecology. 7: 211–227.

Daubenmire, R. 1968. Plant communities: a textbook of plant synecology. New York: Harper and Row.

Daubenmire, R. 1970. Steppe vegetation of Washington. Washington State University

Agricultural Experiment Station Technical Bulletin 62. Pullman, WA: [Publisher unknown].
Existing Vegetation Classification & Mapping Technical Guide 4-3

Daubenmire, R. 1978. Plant geography with special reference to North America. New York:

Academic Press.

Driscoll, R.S.; Merkel, D.L.; Radlof, R.L.; Snyder, D.E.; Hagihara, J.S. 1984. An ecological land

classification framework for the United States. Misc. Pub. 1439. Washington, DC: U.S.

Department of Agriculture, Forest Service.

Ecological Society of America (ESA); The Nature Conservancy; U.S. Geological Survey; U.S.

Federal Geographic Data Committee. 1999. Forming a partnership to further develop and implement

the national vegetation classification standards. Memorandum of Understanding. Washington,

DC: Ecological Society of America.

Estes, J.; Hajic, E.; Tinney, L. 1983. Manual and digital analysis in the visible and infrared

regions. In: Estes, J.; Simonett, D.S., eds. Manual of remote sensing. Falls Church, VA: American

Society for Photogrammetry and Remote Sensing: 258–277

Eyre, F.H. 1980. Forest cover types of the United States and Canada. Washington, DC: Society of

American Foresters.

Federal Geographic Data Committee (FGDC). 1996. FGDC Standards Reference Model. Reston,

VA: Federal Geographic Data Committee, U.S. Geological Survey. http://www.fgdc.gov/standards/

refmod97.pdf. [Date accessed unknown].

Federal Geographic Data Committee (FGDC)—Vegetation Subcommittee. 1997. Vegetation

classification standard. FGDC-STD-005. Reston, VA: Federal Geographic Data Committee, U.S.

Geological Survey. http://www.fgdc.gov/standards/documents/standards/vegetation/vegclass.pdf.

[Date accessed unknown].

Federal Geographic Data Committee (FGDC). 1998. Content standard for digital geospatial

metadata. FGDC-STD-007.3-1998. Reston, VA: Federal Geographic Data Committee. U.S.

Geological Survey. http://www.fgdc.gov/standards/documents/standards/metadata/v2_0698.pdf.

[Date accessed unknown].

Federal Geographic Data Committee (FGDC)—Vegetation Subcommittee. 2001a. Proposal for

revisions to the national standards for physiognomic levels of vegetation classification in the

United States. Reston, VA: Federal Geographic Data Committee, U.S. Geological Survey.

http://www.fgdc.gov/standards/documents/proposals/nvcs_revision.pdf. [Date accessed

unknown].

Federal Geographic Data Committee (FGDC)—Vegetation Subcommittee. 2001b. Proposal for

national standards for the floristic levels of vegetation classification in the United States: associations and alliances. Reston, VA: Federal Geographic Data Committee, U.S. Geological Survey.

http://www.fgdc.gov/standards/documents/proposals/floristic_levels.doc. [Date accessed

unknown]

Flahault, C.; Schröter, C. 1910. Phytogeographische Nomenklatur. Berichte und Anträge 3. In:

3rd international congress of botany, Brussels, Belgium. [Place of publication unknown]:

[Publisher unknown]: 14–22.
4-4 Existing Vegetation Classification & Mapping Technical Guide

Ford-Robertson, F.C. 1971. Terminology of forest science, technology practice and products. The

multilingual forestry terminology, series 1. Washington, DC: Society of American Foresters.

Forman, R.T.T. 1995. Land mosaics: the ecology of landscapes and regions. New York:

Cambridge University Press.

Forman, R.T.T.; Godron, M. 1986. Landscape ecology. New York: John Wiley and Sons. 

Gabriel, H.W.; Talbot, S.S. 1984. Glossary of landscape and vegetation ecology for Alaska.

Alaska Technical Report 10. Washington, DC: U.S. Department of the Interior, Bureau of Land

Management.

Gauch, H.G. 1982. Multivariate analysis in community ecology. New York: Cambridge

University Press. 298 p.

Gerstner, J. 1980. Man as God made him. In: Boice, J.M., ed. Our savior: man, Christ, and the

atonement. Grand Rapids, MI: Baker Books.

Gerwing, J.J. 2004. Life history diversity among six species of canopy lianas in an old-growth

forest of the eastern Brazilian Amazon. Forest Ecology and Management. 190:57–72.

Gillison, A.N.; Brewer, K.R.W. 1985. The use of gradient directed transects or gradsects in natural

resource surveys. Journal of Environmental Management. 20: 103–127.

Gong, P.; Howarth, P.J. 1992. Frequency-based contextual classification and gray-level vector

reduction for land-use identification. Photogrammetric Engineering and Remote Sensing. 58: 423–437.

Gopal, S.; Woodcock, C. 1994. Theory and methods for accuracy assessments of thematic maps

using fuzzy sets. Photogrammetric Engineering and Remote Sensing. 60: 181–188.

Graves, H.S. 1913. Forest mensuration. New York: John Wiley & Sons.

Greig-Smith, P. 1983. Quantitative plant ecology. Berkeley, CA: University of California Press.

Harper, J.L. 1977. Population biology of plants. New York: Academic Press.

Hartgerink, A.P.; Bazzaz, F.A. 1984. Seedling-scale environmental heterogeneity influences individual fitness and population structure. Ecology. 65: 198–206.

Helms, J.A., ed. 1998. The dictionary of forestry. Bethesda, MD: Society of American Foresters.

Hironaka, M.; Fosberg, M.A.; Winward, A.H. 1983. Sagebrush-grass habitat types of southern

Idaho. University of Idaho, Forest, Wildlife, and Range Experiment Station, Bulletin 35.

Moscow, ID: [Publisher unknown].

Jennings, M.D. 2000. Gap analysis: concepts, methods, and recent results. Landscape Ecology.

15: 5–20.

Jennings, M.; Faber-Iangendoen, D.; Peet, R.; et al. 2004. Guidelines for describing associations

and alliances of the U.S. national vegetation classification. Version 3.0. Vegetation Classification

Panel. Washington, DC: Ecological Society of America.
Existing Vegetation Classification & Mapping Technical Guide 4-5

Jensen, J.R. 1996. Digital image processing. New York: Prentice Hall.

Jongman, R.H.G.; ter Braak, C.J.G.; Van Tongeren, O.F.R. 1995. Data analysis in community and

landscape ecology. Cambridge, UK: Cambridge University Press.

Kent, M.; Coker, P. 1992. Vegetation description and analysis: a practical approach. London, UK:

Belhaven Press.

Kimmins, J.P. 1997. Forest ecology: a foundation for sustainable management. 2nd ed. Upper

Saddle River, NJ: Prentice Hall.

Krebs, C.J. 1972. Ecology: the experimental analysis of distribution and abundance. New York:

Harper and Row.

Kuchler, A. 1973. Problems in classifying and mapping vegetation for ecological regionalization.

Ecology. 54: 512–523.

Lachowski, H.; Maus, P.; Golden, M.; et al. 1995. Guidelines for the use of digital imagery for vegetation mapping. EM-7140-25. Washington, DC: U.S. Department of Agriculture, Forest Service.

Lachowski, H.J.; Powell, T.; Wirth, P.; et al. 1996. Monitoring aspen decline using remote sensing

and GIS: Gravelly mountain landscape, southwestern Montana. Dillon, MT: U.S. Department of

Agriculture, Forest Service, Beaverhead-Deerlodge National Forest.

Lillesand, T.M.; Kiefer, R.W. 1987. Remote sensing and image interpretation. 2nd ed. New York:

John Wiley & Sons.

Lillesand, T.M.; Kiefer, R.W. 2000. Remote sensing and image interpretation. 4th ed. New York:

John Wiley & Sons.

Lincoln, R.J.; Boxshall, G.A.; Clark, P.F. 1982. A dictionary of ecology, evolution and systematics.

New York: Cambridge University Press.

Lincoln, R.; Boxshall, G.; Clark, P. 1998. A dictionary of ecology, evolution and systematics.

2nd ed. New York: Cambridge University Press.

Ludwig, J.A.; Reynolds, J.F. 1988. Statistical ecology: a primer on methods and computing. New

York: John Wiley & Sons.

McCune, B.; Mefford, M.J. 1999. Multivariate analysis of ecological data, PC-ORD. Version

4.17. Gleneden Beach, OR: MjM Software Design.

McCune, B.; Grace, J.B.; Urban, D.L. 2002. Analysis of ecological communities. Gleneden

Beach, OR: MjM Software Design.

Mill, J.S. 1872. A system of logic. 8th ed., as reprinted in Nagel, E., ed. 1950. John Stuart Mill’s

philosophy of scientific methods. New York: Hafner Press.

Mosby, H.S. 1980. Reconnaissance mapping and map use. In: Schemnitz, S.D., ed. Wildlife

management techniques manual. Washington, DC: The Wildlife Society: 277–290.
4-6 Existing Vegetation Classification & Mapping Technical Guide

Mueggler, W.F. 1988. Aspen community types of the Intermountain region. General Technical

Report GTR-INT-250. U.S. Department of Agriculture, Forest Service.

Mueggler, W.F.; Stewart, W.L. 1980. Grassland and shrubland habitat types of western Montana.

Gen. Tech. Rep. INT-66. Ogden, UT: U.S. Department of Agriculture, Forest Service,

Intermountain Forest and Range Experiment Station.

Mueller-Dombois, D.; Ellenberg, H. 1974. Aims and methods of vegetation ecology. New York:

John Wiley & Sons.

NatureServe. 2001. NatureServe Explorer: An online encyclopedia of life. Version 1.4. Arlington,

VA. http://www.natureserve.org/explorer. [Date accessed unknown].

NatureServe. 2004. International classification of ecological communities: terrestrial vegetation.

Natural heritage central databases. Arlington, VA.

Nellis, M.D.; Briggs, J.M. 1989. The effect of spatial scale on Konza landscape classification

using textural analysis. Landscape Ecology. 2: 93–100.

Office of Management and Budget (OMB). 1990. Coordination of geographic information and

related spatial data activities. Circular A-16. Washington, DC: Office of Management and Budget 

Oliver, C.D.; Larson, B.C. 1990. Forest stand dynamics. New York: McGraw Hill.

Pfister, R.D. Arno, S.F. 1980. Classifying forest habitat types based on potential climax vegetation.

Forest Science. 26: 52–70.

Pielou, E.C. 1984. The interpretation of ecological data: a primer on classification and ordination.

New York: John Wiley & Sons.

Podani, J. 2000. Introduction to the exploration of multivariate biological data. Leiden, Hungary:

Backhuys Publishers.

Reid, M.; Comer, P.; Barrett, H.; et al. 2002. International classification of ecological communities:

terrestrial vegetation of the United States. Sagebrush vegetation of the western United States.

Final report for the USGS forest and rangeland ecosystem science center, Corvallis, OR.

Arlington, VA: NatureServe. http://sagemap.wr.usgs.gov/

sage_grouse_documents.htm. [Date accessed unknown].

Robinson, A.H.; Sale, R.; Morrison, J.L. 1978. Elements of cartography. 4th ed. New York: John

Wiley & Sons.

Robinson, J.W.; Tilton, J.C. 1991. Refinement of ground reference data with segmented image

data. In: Multisource data integration in remote sensing, NASA Conf. Publ. 3099. College Park,

MD: University of Maryland: 3–10.

Ryherd, S.; Woodcock, C. 1996. Combining spectral and texture data in the segmentation of

remotely sensed images. Photogrammetric Engineering and Remote Sensing. 62: 181–194.
Existing Vegetation Classification & Mapping Technical Guide 4-7

Scheiner, S.M. 1992. Measuring pattern diversity. Ecology. 73: 1860–1867.

Shiflet, T.N., ed. 1994. Rangeland cover types of the United States. Denver, CO: Society for

Range Management.

Simmons, M.A.; Cullinan, V.I.; Thomas, J.M. 1992. Satellite imagery as a tool to evaluate ecological

scale. Landscape Ecology. 7: 77–85.

Simonett, D.S.; Ulaby, F.T.; Estes, J.E.; Thorley, G.A. 1983. Manual of remote sensing. Falls

Church, VA: American Society of Photogrammetry.

Smith, D.M. 1986. The practice of silviculture. New York: John Wiley & Sons.

Society for Range Management (SRM). 1989. A glossary of terms used in range management.

Denver, CO: Society for Range Management.

Stage, A.R.; Alley, J.R. 1973. An inventory design using stand examinations for planning and

programming timber management. Research Paper RP-INT-126. Ogden, UT: U.S. Department of

Agriculture, Forest Service.

Stehman, S.V. 1992. Comparison of systematic and random sampling for estimating the accuracy

of maps generated from remotely sensed data. Photogrammetric Engineering and Remote

Sensing. 58: 1343–1350.

Story, M.; Congalton, R.G. 1986. Accuracy assessment: a user’s perspective. Photogrammetric

Engineering and Remote Sensing. 52: 397–399.

Stringham, T.K.; Krueger, W.C.; Shaver, P.L. 2001. States, transitions, and thresholds: further

refinement for rangeland applications. Special Report 1024. Oregon State University,

Agricultural Experiment Station. Corvallis, OR: [Publisher unknown].

Svalberg, T.; Tart, D.; Fallon, D.; et al. 1997. Bridger-east ecological unit inventory, Bridger-Teton

National Forest. Final draft. Jackson, WY: U.S. Department of Agriculture, Forest Service,

Bridger-Teton National Forest. 

Tart, D.L. 1996. Big sagebrush plant associations of the Pinedale Ranger District. Final review

draft. Jackson, WY: U.S. Department of Agriculture, Forest Service, Bridger-Teton National

Forest.

Toumey, J.W. 1937. Foundations of silviculture upon an ecological basis. New York: John Wiley

& Sons.

Trewartha, G.T. 1968. An introduction to climate. 4th ed. New York: McGraw-Hill.

Turner, M.G.; O’Neill, R.V.; Gardner, R.H.; Milne, B.T. 1989. Effects of changing spatial scale

on the analysis of landscape pattern. Landscape Ecology. 3: 153–162.

Tüxen, R. 1956. Die heutige naturliche potentielle Vegetation als Gegenstand der vegetationskartierung. Remagen. Berichtze zur Deutschen Landekunde. 19: 200–246.
4-8 Existing Vegetation Classification & Mapping Technical Guide

U.S. Department of Agriculture (USDA), Forest Service. 1985. FSH 2409.17—Silvicultural

practices handbook. Washington, DC: Department of Agriculture, Forest Service.

U.S. Department of Agriculture (USDA), Forest Service. 1991a. FSH 2090.11—Ecological classification and inventory handbook. Missoula, MT: Department of Agriculture, Forest Service, Northern

Region.

U.S. Department of Agriculture (USDA), Forest Service. 1991b. FSM 2060—Ecosystem

Classification, Interpretation, and Application. Washington, DC: Department of Agriculture,

Forest Service.

U.S. Department of Agriculture (USDA), Forest Service. 1999. Implementation of remote sensing

for ecosystem management. EM-7140-28. Washington, DC: U.S. Department of Agriculture,

Forest Service, Remote Sensing Advisory Team and Remote Sensing Applications Center.

U.S. Department of Agriculture (USDA), Forest Service. 2002. Draft FSM 1940—Resource

Inventory and Monitoring. Washington, DC: Department of Agriculture, Forest Service,

Ecosystem Management Staff.

U.S. Department of Agriculture (USDA), Forest Service. 2003. Ocular plant composition PC

field guide. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rangeland

Management Service Center. 

U.S. Department of Agriculture (USDA), Forest Service. 2004a. Common Stand Exam Users

Guide, V.1.6. Washington, DC: Department of Agriculture, Forest Service, Natural Resource

Information System. 

U.S. Department of Agriculture (USDA), Forest Service. 2004b. Cover-Frequency Form PC Field

Guide. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rangelend

Management Service Center. 

U.S. Department of Agriculture (USDA), Forest Service. 2004c. Forest Service metadata users

guide—metadata terms and definitions. Washington, DC: U.S. Department of Agriculture, Forest

Service, Geospatial Advisory Committee: http://www.fs.fed.us/gac/metadata/glossary.html.

U.S. Department of Agriculture (USDA), Forest Service. 2004d. Line Intercept PC Field Guide.

Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rangeland Management

Service Center. 

U.S. Department of Agriculture (USDA), Natural Resource Conservation Service (NRCS). 1997.

National range and pasture handbook. Washington, DC: U.S. Department of Agriculture, Natural

Resources Conservation Service.

U.S. Department of Agriculture (USDA), Natural Resource Conservation Service (NRCS). 2002.

The PLANTS Database. Version 3.5. Baton Rouge, LA: National Plant Data Center.

http://plants.usda.gov. [Date accessed unknown].
Existing Vegetation Classification & Mapping Technical Guide 4-9

U.S. Department of Agriculture (USDA), Soil Survey Division Staff. 1993. Soil survey manual.

Soil Conservation Service Handbook 18. Washington, DC: U.S. Department of Agriculture, Soil

Conservation Service. 

U.S. Department of Agriculture (USDA), Soil Survey Division. 1999. Soil taxonomy: a basic

system of soil classification for making and interpreting soil surveys. 2nd ed. Natural Resources

Conservation Service Agriculture Handbook 436. Washington, DC: U.S. Department of

Agriculture, Natural Resources Conservation Service.

U.S. Geological Survey (USGS); National Park Service (NPS). 2002. USGS—NPS vegetation

mapping program. http://biology.usgs.gov/npsveg/products/parkname.html. [Date accessed

unknown].

United Nations-Economic Commission for Europe/Food and Agriculture Organization of the

United Nations (UN-ECO/FAO). 1995. Background note on ongoing activities relating to land

use and land cover classification. Nairobi, Kenya.

United Nations-Economic Commission for Europe/Food and Agriculture Organization of the

United Nations (UN-ECO/FAO). 1997. Temperate and boreal forest resources assessment 2000:

terms and definitions. New York.

Westoby, M.; Walker, B; Noy-Meir, I. 1989. Opportunistic management for rangelands not at

equilibrium. Journal of Range Management. 42: 266–274.

Whitaker, R.H. 1970. Communities and ecosystems., New York: Macmillan.

Winthers, E.; Fallon, D.; Haglund, J.; et al. 2005. Terrestrial ecological unit inventory technical

guide. Washington, DC: U.S. Department of Agriculture, Forest Service.

Woodcock, C.E.; Gopal, S. 1992. Accuracy assessment of the Stanislaus forest using fuzzy sets.

In: Proceedings from the 4th Biennial Forest Service Remote Sensing Applications Conference,

Orlando, FL: 378–394. 
4-10 Existing Vegetation Classification & Mapping Technical Guide
Existing Vegetation Classification & Mapping Technical Guide 5-1

Glossary

For some terms, one or more definitions are given, and often more than one is in common usage. 

abiotic. Pertaining to the nonliving parts of an ecosystem, such as soil particles, bedrock, air, and

water (Helms 1998).

absolute composition. List of the absolute amounts of each plant species present in a given area

or stand. Express the amount of each plant taxon as absolute percent cover (FGDC 1997,

Jennings et al. 2004).

abundance. The total number of individuals of a taxon or taxa in an area, volume, population or

community often measured as cover in plants (Lincoln et al. 1998).

accuracy. The degree to which a measured quantity approaches the true value of what is being

measured (Lincoln et al. 1998).

accuracy assessment. Process by which the accuracy or correctness of an image (or map) is

evaluated.

accuracy assessment site. Site identified on a satellite image (or map) and on a reference dataset

for the purposes of accuracy assessment of the image or map (Lachowski et al. 1996).

alliance. (1) A grouping of associations with a characteristic physiognomy and sharing one or

more diagnostic species, which, as a rule, are found in the uppermost or dominant stratum of the

vegetation (Jennings et al. 2004). (2) A physiognomically uniform group of associations sharing

one or more diagnostic (dominant, differential, indicator, or character) species that, as a rule, are

found in the uppermost stratum of the vegetation (FGDC 1997).

arc. In reference to GIS, within a spatial context, a locus of points that forms a curve that is

defined by a mathematical expression (adapted from FGDC 1998).

association. (1) A recurring plant community with a characteristic range in species composition,

specific diagnostic species, and a defined range in habitat conditions and physiognomy or structure

(Jennings et al. 2004). (2) A physiognomically uniform group of existing vegetation stands that

share dominant overstory and understory species. These occur as repeatable patterns across the

landscape (adapted from FGDC 1997). (3) A plant community type of definite floristic composition, uniform habitat conditions, and uniform physiognomy (Flahault and Schröter 1910, as cited

in Jennings et al. 2004). Definition 3 is the most authoritative; the Federal Geographic Data

Committee (FGDC) modified it for existing vegetation, and the modification is followed in this

technical guide. 

association table. Summary of species data by plot for a given association. Association tables

are essential to determine plot membership in a type and are used for comparison of individual

plots to other plots in a type. They may include information on environmental characteristics

(e.g., slope, aspect, or elevation). See also synthesis table. 
5-2 Existing Vegetation Classification & Mapping Technical Guide

attribute. One of a set of descriptive terms; a characteristic (adapted from Lincoln et al. 1998).

business needs. Ongoing tasks related to a particular business or project and the information and

other support contributing to the completion of these tasks.

canopy closure. The proportion of ground, usually expressed as a percentage, that is occupied by

the perpendicular projection downward of the aerial parts of the vegetation of one or more

species. It usually refers to the tree life form of the uppermost canopy, as seen from above, and

cannot exceed 100 percent. Canopy closure is similar in concept to absolute canopy.

canopy cover. (1) The proportion of ground, usually expressed as a percentage, that is occupied

by the perpendicular projection down on to it of the aerial parts of the vegetation or the species

under consideration. The additive cover of multiple strata or species may exceed 100 percent

(FGDC 1997). (2) The percentage of ground covered by a vertical projection of the outermost

perimeter of the natural spread of foliage of plants. Small openings in the canopy are included

(SRM 1989, USDA NRCS 1997). Canopy cover is synonymous with canopy closure (Helms

1998). For woody plants, canopy cover is synonymous with crown cover (USDA NRCS 1997,

Helms 1998).

character species. A species that shows a distinct maximum concentration, quantitatively and by

presence, in a well-definable vegetation type (Mueller-Dombois and Ellenberg 1974).

class. (1) The first (highest) level in the National Vegetation Classification Standard (NVCS)

hierarchy based on the structure of the vegetation and determined by the relative percentage of

cover and the height of the dominant, uppermost life forms (Ecological Society of America 1999).

(2) A group of individuals or other units similar in selected properties and distinguished from all

other classes of the same population by differences in these properties (Buol et al. 1973).

classification. (1) The process of grouping similar entities into named types or classes based on

shared characteristics. (2) The grouping of similar types (in this case, vegetation) according to

criteria (in this case, physiognomic and floristic) that are considered significant for this specific

purpose. The rules for classification must be clarified before the types are identified in the classification standard. The classification methods should be clear, precise, quantitative where possible,

and based on objective criteria so that the outcome will be the same no matter who developed the

definition (or description). Classification by definition involves definition of class boundaries

(FGDC 1997, citing UN-EP/FAO 1995). 

classification methodology standards. Procedures to follow to implement a data classification

standard. Procedures describe how data are analyzed to produce a classification (FGDC 1996).

classification scheme or system. A set of target classes or a legend that serves as the basis of a

classification or map (Lachowski et al. 1996).

clearinghouse. See National Geospatial Data Clearinghouse (FGDC 1998).

climax. A self-replacing plant community or species with no evidence of replacement by 

other plants.
Existing Vegetation Classification & Mapping Technical Guide 5-3

climax plant community. Stable community in an ecological succession that is able to reproduce

itself indefinitely under existing environmental conditions in the absence of disturbance. Viewed

as the final stage or endpoint in plant succession for a site. The climax community develops and

maintains itself in steady state conditions. 

community. (1) A general term for an assemblage of plants living together and interacting

among themselves in a specific location; no particular ecological status is implied. (2) Any group

of organisms interacting among themselves (Daubenmire 1978).

community composition. The kinds, absolute amounts, or relative proportions of plant species

present in a given area or stand. It can be described qualitatively or quantitatively. The latter may

use absolute amounts or relative proportions of the plant taxa present. Express the amount of

each plant taxon as percent cover (FGDC 1997, Jennings et al. 2004). 

community type. An aggregation of all plant communities with similar structure and floristic

composition. A unit of vegetation in a classification with no particular successional status implied.

composition. (1) The amount or proportion of the plant species on a given area (adapted from

SRM 1989). (2) A list of the species that comprise a community or any other ecological unit

(Lincoln et al. 1998).

compositional group. A map unit that comprises a grouping of alliances or dominance types

with similar taxonomic composition and physiognomy (Brackney and Jennings 1998).

compound element. A group of data elements and other compound elements. Compound elements

represent higher level concepts that cannot be represented by individual data elements (FGDC 1998).

constancy. The number of occurrences of a species in a group of plots, all the same size divided

by the total number of plots. Expressed as a percentage; i.e., if a particular community has 10

plots and a species is found in 8 of the 10, the constancy of that species is 80 percent.

coordinates. In mapping, pairs of numbers that express horizontal distances along orthogonal

axes; or, triplets of numbers measuring horizontal and vertical distances (FGDC 1998).

compositional groups. Map units that comprise a grouping of alliances or dominance types with

similar taxonomic composition and physiognomy (Brackney and Jennings 1998).

cover. Usually meant as canopy cover that is the gross outline of the foliage of an individual plant or

group of plants in a stand or plot. Expressed as a percent of the total area of the plot and may exceed

100 percent if more than one layer is considered. See also canopy cover and vegetation cover.

cover type. A designation based on the plant species forming a plurality of composition in a

given area, e.g., oak-hickory (FGDC 1997). The Society of American Foresters (SAF) forest

cover types (Eyre 1980) and the Society for Range Management (SRM) rangeland cover types

(Shiflet 1994) are examples of cover types. 

crown closure (percent). Percentage of area covered by the vegetation canopy (USDA Forest

Service 1999).
5-4 Existing Vegetation Classification & Mapping Technical Guide

data classification standard. Provides groups or categories of data that serve an application,

e.g., wetland and soil classifications (FGDC 1996). In other words, a data classification standard

specifies and defines a set of categories that must be used or crosswalked to by Federal agencies.

The physiognomic levels of the National Vegetation Classification Standard (NVCS) are a data

classification standard.

data element. A logically primitive item of data (FGDC 1998).

data standards. Describe objects, features, or items that are collected, automated, or affected by

activities or functions of agencies. Data standards are semantic definitions that are structured in

a model (FGDC 1996).

data steward. A person designated to manage large datasets and ensure their updating and quality.

dataset. Collection of related data. See also geospatial data (USDA Forest Service 2004c).

diagnostic species. Any species or group of species whose relative constancy or abundance

clearly differentiates one type from another (Jennings et al. 2004). This definition implies that

diagnostic species must be determined empirically through analysis of plot data (Mueller-Dombois

and Ellenberg 1974).

differential species. A plant species that, because of its greater fidelity in one kind of community

than in others, can be used to distinguish vegetation units (Gabriel and Talbot 1984, as cited in

Jennings et al. 2004).

differentiating characteristics. Properties selected as the basis for grouping individuals into

classes (Buol et al. 1973).

digital elevation model (DEM). Digital data file containing an array of elevation information

over a portion of the Earth’s surface (USDA Forest Service 1999).

digital image. A two-dimensional array of regularly spaced picture elements (pixels) constituting

a picture (FGDC 1998).

digital number (DN). The numerical value of a specific pixel. The DN corresponds to the average

radiance measured in each pixel (Lachowski et al. 1996).

digital orthophoto quad (DOQ). Digital representation of an aerial photo with ground features

located in their “true” positions (USDA Forest Service 1999).

division. The level in the FGDC physiognomic hierarchy separating earth cover into either vegetated or nonvegetated categories (ESA et al. 1999). 

dominance. The extent to which a given species has a strong influence in a community because

of its size, abundance, or coverage. Strong dominance affects the fitness of associated species

(adapted from Lincoln et al. 1998). 

dominance type. A recurring plant community defined by the dominance of one or more species

that are usually the most important ones in the uppermost or dominant layer of the community,

but sometimes of a lower layer of higher coverage (adapted from Gabriel and Talbot 1984, as

cited in Jennings et al. 2004).
Existing Vegetation Classification & Mapping Technical Guide 5-5

dominant. An organism exerting considerable influence on a community by its size, abundance,

or coverage (Lincoln et al. 1998).

dominant species. The species with the highest percentage of cover, usually in the uppermost

layer (Kimmins 1997, as cited in Jennings et al. 2004).

dynamic sampling. The collection and analysis of resource data to measure changes in the

amounts, spatial distribution, or condition of resource types or parameters over time (adapted

from Helms 1998).

earth cover. The observed physical cover as seen on the ground or through remote sensing.

Examples of earth cover classes include vegetated, unvegetated, water, and artificial cover

(human construction). A given piece of land can fit in one earth cover class only, which makes

earth cover mutually exclusive at the same scale of mapping (FGDC 1997).

ecosystem. A complete interacting system of organisms and their environment (USDA Forest

Service 1991).

ecotone. The boundary or transitional zone between adjacent communities or biomes; tension

zone (Lincoln et al. 1998).

electromagnetic spectrum. The range of energy transmitted through space in the form of electric

or magnetic waves, extending from cosmic waves to radio waves. Included in this spectrum are

visible and infrared regions that are particularly important for land remote sensing applications

(Lachowski et al. 1996).

element. Parts of the sections or chapters in the Federal Geographic Data Committee (FGDC)

Content Standards for Digital Geospatial Metadata (http://www.fs.fed.us/gac/metadata/glossary.html).

Elements are numbered starting with the section number. A set of elements with subparts is

called a compound element, for example, 2.1.1 (Data Quality Information, Attribute Accuracy,

Attribute Accuracy Report). The FGDC standard contains 334 different elements, 119 of which

exist only to contain other elements (USDA Forest Service 2004c).

error matrix. A table used as a starting point for a series of descriptive and analytical statistical

techniques used for accuracy assessment of maps or other products. Error matrices score each

observation (sample) according to the class it has been assigned to in the classified map and the

“true” class, as determined by reference data. Error matrixes are sometimes referred to as confusion

or difference matrixes because reference data is not always absolutely accurate (Lachowski et al.

1996).

evaluation. The comparison of dynamic sampling results to management objectives consisting of

predetermined standards, expected norms, threshold values, and/or trigger points.

existing vegetation. (1) The plant cover or floristic composition and vegetation structure occurring

at a given location at the current time. (2) The plant species existing at a location at the present

time. Contrast with potential natural vegetation. 
5-6 Existing Vegetation Classification & Mapping Technical Guide

feature selection. A preprocessing technique that aims to reduce the amount of data in an image

by isolating individual raw bands for further image processing (Lachowski et al. 1996).

Federal Geographic Data Committee (FGDC). An interagency committee, organized in 1990

under the Office of Management and Budget (OMB) Circular A-16 that promotes the coordinated

use, sharing, and dissemination of geospatial data on a national basis. The FGDC is composed of

representatives from 17 Cabinet-level and independent Federal agencies (USDA Forest Service

2004c).

FGDC compliant metadata. To be compliant with the Federal Geographic Data Committee (FGDC)

metadata standard, a metadata record must successfully pass through the FGDC metaparser. The

metaparser is often run directly from the metadata creation tool, such as MetaLite, but can also

be run separately. If the record is incomplete or improperly formatted, the metaparser flags the

errors. In general terms, FGDC-compliant metadata can be relatively simple or complex depending

on the number of elements that are required. If the metadata exists for a required element, it should

be entered (USDA Forest Service 2004c).

fidelity. The degree of restriction of a plant species to a particular situation, community, 

or association (Lincoln et al. 1998).

flora (adj. floral, floristic). (1) All the plant species that make up the vegetation of a given area

(Allaby 1994). (2) The plant life of a given region, habitat, or geological stratum (Lincoln et al. 1998).

floristic classification. Classification of plant communities, emphasizing species composition.

It may include considerations of species abundance, dominance, growth form, and so on.

Emphasize the plant species comprising the vegetation instead of life forms or structure. Floristic

classifications are based on community composition and/or diagnostic species.

floristic composition. A list of plant species of a given area, habitat, or association (Lincoln et

al. 1998).

foliar cover. The percentage of ground covered by the vertical projection of the aerial portion of

plants. Small openings in the canopy and intraspecific overlap are excluded (SRM 1989). 

forb. Broad-leaved herbaceous plant (adapted from FGDC 1997).

fuzzy logic. A type of reasoning designed to accommodate ambiguity. Using fuzzy sets in accuracy assessment permits explicit recognition of the possibility of ambiguity regarding appropriate

map labels for some locations on a map/classification. This recognition can help the user determine

the relative (not absolute) accuracy of a particular classification, and thus the usefulness of that

classification for applications requiring varying levels of accuracy (Lachowski et al. 1996).

geographic information system (GIS). The term frequently applied to geographically oriented

computer technology. In its broadest sense, GIS is a system for capturing, storing, checking,

manipulating, analyzing, and displaying data that are spatially referenced to the Earth

(Lachowski et al. 1996).
Existing Vegetation Classification & Mapping Technical Guide 5-7

geometric correction. An image processing technique that reorients the image data to compensate

for the Earth’s rotation and variations in satellite position and attitude (USDA Forest Service 1999).

geospatial data. Information that identifies the geographic location and characteristics of natural

or constructed features and boundaries on the earth. This information may be derived from

remote sensing, mapping, and surveying technologies (FGDC 1998).

global positioning system (GPS). An array of space satellites and ground receivers that use

geometry to provide information about the precise latitude, longitude, and elevation of a particular

point (Lachowski et al. 1996).

gradsect technique. The gradsect technique is a form of stratified random sampling that may be

cost effective for sampling vegetation patterns along environmental gradients (Gillison and

Brewer 1985). See also representative sampling.

grid. (1) A set of grid cells forming a regular, or nearly regular, tessellation of a surface. (2) Set

of points arrayed in a pattern that forms a regular, or nearly regular, tessellation of a surface. The

tessellation is regular if formed by repeating the pattern of a regular polygon, such as a square,

equilateral triangle, or regular hexagon. The tessellation is nearly regular if formed by repeating

the pattern of an “almost” regular polygon such as a rectangle, nonsquare-parallelogram, or nonequilateral triangle (FGDC 1998).

group. The level in the National Vegetation Classification Standard (NCVS) hierarchy below

subclass based on leaf characters and identified and named in conjunction with broadly defined

macroclimatic types to provide a structural-geographic orientation (ESA et al. 1999).

habit. The general growth form and appearance of a species. See also growth form and 

physiognomy.

habitat. (1) The combination of environmental or site conditions and ecological processes influencing a plant community (Jennings et al. 2004). (2) Area or type of environment in which an

organism or population normally lives or occurs.

herb. Nonwoody vascular plants, such as grasses, grass-like plants, and forbs (adapted from

FGDC 1997).

high resolution visible (HRV). The type of sensor mounted on SPOT satellites. The HRV “push

broom” scanning system is different than the Landsat mirror-sweep scanning systems, and has

the advantage of eliminating geometric errors introduced in the sensing process by variations in

scan mirror velocity (Lachowski et al. 1996).

homogeneous types. Map units composed of a homogeneous condition of vegetation or uniform

type; map unit that comprises a single alliance or dominance type, with at least 85 percent of the

area in a polygon. 

horizontal. Tangent to the geoid or parallel to a plane that is tangent to the geoid (FGDC 1998).
5-8 Existing Vegetation Classification & Mapping Technical Guide

image classification. The process of assigning the pixels of an image to discrete categories or

classes (Lachowski et al. 1996).

image interpretation. (1) The systematic examination of image data; frequently involves other

supporting materials, such as maps and field observations (Lillesand and Kiefer 2000). (2) Basis

for delineation of map units is normally discontinuities in texture reflecting life form composition,

stocking, tree crown size differences, and/or apparent tree height (Stage and Alley 1973).

image processing. A general term referring to manipulation of digital image data; includes

image enhancement, image classification, and image preprocessing (or rectification) operations

(Lachowski et al. 1996).

image segmentation. The process of dividing digital images into spatially cohesive units or regions.

These regions represent discrete objects or areas in the image (Ryerd and Woodcock 1996).

indicator species. (1) A species whose presence, abundance, or vigor is considered to indicate

certain environmental conditions (Gabriel and Talbot 1984, as cited in Jennings et al. 2004). 

(2) Species that are sensitive to important environmental feature of a site such that its constancy

or abundance reflect significant changes in environmental factors. (3) Plant whose presence

indicates specific site conditions or a type.

inventory. The systematic acquisition, analysis, and organization of resource information needed

for planning and implementing land management (adapted from USDA NRCS 1997).

land cover. (1) The ecological state and physical appearance of the land surface, e.g., forest and

grassland. Note that land may be changed by human intervention, natural disturbances, or plant

succession (Helms 1998). (2) The observed physical categories of an area as seen on the ground

or through remote sensing. Examples include vegetated, nonvegetated, surface water, urban and

developed. Land cover classes are mutually exclusive at the same scale of mapping (adapted

from FGDC 1997).

Landsat. Name for the series of Earth-observing satellites first launched in 1972 by NASA;

originally named Earth Resource Technology Satellite (ERTS). Landsat satellites serve as platforms

for several sensors including the return beam vidicon, Landsat Multispectral Scanner (MSS), and

Landsat Thematic Mapper (TM) (Lachowski et al. 1996).

Layer (GIS). A digital information storage unit, also known as theme. Different kinds of information (e.g., roads, boundaries, lakes, and vegetation) can be grouped and stored as separate

digital layers or themes in a GIS (Lachowski et al. 1996).

layer or stratum. (1) A structural component of a community consisting of plants of approximately

the same height structure (e.g., tree, shrub, and herbaceous layers). (2) The definition and measurement of these structural components in their vertical and height relationships to each other (e.g.,

tree subcanopy layer, shrub understory layer) (adapted from Ecological Society of America 1999).

life form. (1) The characteristic structural features and method of perennation of a plant species;

the result of the interaction of all life processes, both genetic and environmental (Lincoln et al.

1998). Life form is related to growth form, physiognomy, and habit but also includes consideration
Existing Vegetation Classification & Mapping Technical Guide 5-9

of the type and position of renewal (perennating) buds that the other terms typically do not

include. (2) Includes gross morphology (size, woodiness, etc.), leaf morphology, life span, and

phonological (or life cycle) phenomena (Barbour et al. 1980).

map. (1) A spatial representation, usually graphic on a flat surface, of spatial phenomena (FGDC

1998). (2) A representation, usually on a plane surface, of a region of the Earth or heavens

(Robinson et al. 1978).

map feature. An individual area or delineation on a map is a map feature. Specific map features

are nonoverlapping and geographically unique, but will contain one or more thematic components

(i.e., map unit) that may be repeated across multiple map features. Map feature is synonymous

with the commonly used terms of polygon and region.

map levels. Define different intensities of field study, different degrees of detail in mapping,

different levels of abstraction in defining and naming map units, and different map unit designs.

Adjustment in these elements forms the basis for differentiating four levels of vegetation mapping:

national, broad, scale, and base. The levels are intended to aid in the identification of the operational procedures used to conduct vegetation mapping activities and also indicate general levels

of the quality control applied during mapping. These levels affect the kind and precision of subsequent interpretations and predictions (adapted from USDA Soil Survey Division Staff 1993).

map scale. The extent of reduction required to display a portion of the Earth’s surface on a map;

defined as a ratio of distances between corresponding points on the map and on the ground

(Robinson et al. 1978). Scale indirectly determines the information content and size of the area

being represented. The mapping scale is determined by the agency’s business needs and the characteristics of the data obtained for the project area. Maps generated from digital imagery can

appropriately be displayed at a range of scales.

map unit. A collection of features defined and named the same in terms of their vegetation characteristics (USDA Soil Survey Division Staff 1993). Each map unit differs in some respect from

all others in a geographic extent. Map units are differentiated in map unit design and defined in a

map unit description. Design of map units generalizes the taxonomic units present to the smallest

set that (1) meets the objectives of the map, and (2) is feasible to delineate with available

resources and technology. 

map unit aggregation type. A map unit attribute that describes the arrangement of vegetated

condition found in a map feature or polygon. An aggregation type consists of a homogenous

dominance type, plant association, compositional group, or vegetation complex arrangements of

dominance types or plant associations.

map unit design. The process establishing the relationship between vegetation classifications

and map products depicting them.

metadata. Refers to “data about data”; describes the content, quality, condition, and other characteristics of a given set of data. Its purpose is to provide information about a dataset or some

larger data holdings to data catalogues, clearinghouses, and users. Metadata is intended to provide

a capability for organizing and maintaining an institution’s investment in data to provide information
5-10 Existing Vegetation Classification & Mapping Technical Guide

for the application and interpretation of data received through a transfer from an external source

(Jennings et al. 2004, as modified from FGDC 1997).

minimum map unit (MMU). Smallest map feature delineated; requirements vary for different

map levels.

modeling. In reference to geospatial data, the process of creating a new GIS layer by combining

or operating on existing layers. Modeling creates images) that contain several types of information

comprising several GIS variables; e.g., a scene may be considered in terms of its vegetation,

elevation, water, and climate at the same time (Lachowski et al. 1996).

monitoring. (1) The systematic collection, analysis, and interpretation of resource data to evaluate

progress toward meeting management objectives (adapted from SRM 1989). (2) The collection

and analysis of resource data to measure changes in the amounts, spatial distribution, or condition

of resource types or parameters over time.

multispectral. Sensors or images that record or display data from two or more bands of the

electromagnetic spectrum (USDA Forest Service 1999).

natural classification. Classification in which the differentiating criteria are selected to “bring

out relationships of the most important properties of the population being classified, without

reference to any single specified and applied objective.” (Buol et al. 1973). Also called scientific

classification.

natural/seminatural. (1) Areas dominated by native or established vegetation that has not been

cultivated or treated with any annual management or manipulation regime. (2) Areas that cannot be

assessed as to whether the vegetation was planted or cultivated by humans (adapted from FGDC 1997).

noise. Nonmeaningful variation in species abundances that obscure patterns and relationships in

the dataset. Sources of noise include chance distribution and establishment of seeds, local disturbances, microsite variation, outliers, and misidentification of species.

nonvegetated (mapping). In mapping, this category includes the FGDC sparsely Vegetated class

combined with the Nonvegetated class. Vegetation comprises less than 10-percent cover at the

peak of the growing season. In the land cover classification system (Anderson Level I), water,

barren land, perennial snow/ice, and urban/built-up land are examples of nonvegetated landscapes

(Anderson et al. 1976).

nonvegetated (soil). Landscape usually associated with open water or human-modified land,

such as heavy industrial commercial transportation facilities (adapted from USDA Soil Survey

Division Staff 1993).

object. A digital representation of all or part of an entity instance (FGDC 1998).

omission error. In remote sensing, a mistake of exclusion occurring in an image classification.

Omission errors are displayed in an error matrix during the accuracy assessment process and

serve to alert the analyst to mislabeling of reference sites (Lachowski et al. 1996).
Existing Vegetation Classification & Mapping Technical Guide 5-11

order. In the National Vegetation Classification Standard hierarchy, order is the lower level

immediately following division. The orders in the Vegetated division are generally defined by

dominant life form (tree, shrub, dwarf shrub, herbaceous, or nonvascular) (FGDC 1997).

outlier. Refers to data or a sample that has low similarity to all other samples in the dataset.

overall accuracy. A common measure of a classification’s accuracy. Overall accuracy is calculated

by dividing the total number of correct samples by the total number of assessment sites

(Lachowski et al. 1996).

overstory tree diameter. The mean diameter at breast height (4.5 feet or 1.37 meters above the

ground) for the trees forming the upper or uppermost canopy layer (Helms 1998).

panchromatic. Refers to single band imagery (USDA Forest Service 1999).

patch. A relatively homogenous nonlinear area that differs from its surroundings (Forman 1995);

can specifically describe forested patches, nonforest vegetation patches, rock/barren patches, or

water patches. 

pattern. Repeating coordinated species abundance and groups of samples with similar species

composition.

physiognomic classification. A level in the classification hierarchy defined by the relative percent

canopy cover of the tree, shrub, dwarf shrub, herb, and nonvascular life form in the uppermost

strata during the peak of the growing season (FGDC 1997).

physiognomy. (1) The characteristic feature or appearance of a plant community or vegetation

(Lincoln et al. 1998). (2) The overall appearance of a kind of vegetation (Daubenmire 1968,

Barbour et al. 1980). (3) The expression of the life forms of the dominant plants and vegetation

structure (Mueller-Dombois and Ellenberg 1974, Barbour et al. 1980).

pixel. Two-dimensional picture element that is the smallest nondivisible element of a digital

image (FGDC 1998).

platform. In remote sensing, the physical object (e.g., balloon, rocket, or satellite) that carries

the remote sensor. In computing use, may also refer to a type of technical system that is used for

processing, displaying, querying, and storing information, e.g., a “technology platform”

(Lachowski et al. 1996).

plot. (1) “A circumscribed sampling area for vegetation” (Lincoln et al. 1998). (2) “any twodimensional sample area of any size. This includes quadrates, rectangular plots, circular plots

and belt transects (very long rectangular plots). Belt transects are often called strips or transects”

(Mueller-Dombois and Ellenburg 1974).

point. In reference to geospatial data, a dimensional-dimensional object that specifies geometric

location. One coordinate pair or triplet specifies the location. Area point, entity point, and label

point are special implementations of the general case (USDA Forest Service 2004c).
5-12 Existing Vegetation Classification & Mapping Technical Guide

polar. A classification of climate based on the Koppen System for regions where the warmest

month is colder than 50 °F (10 °C) (Bailey 1980).

pocosin wetlands. An upland swamp or bog of the coastal plain of the southeastern United

States (Helms 1998).

potential natural vegetation (PNV). The vegetation that would become established, if all successional sequences were completed without interference by man under the present climatic and

edaphic conditions (Tüxen 1956, as cited in Mueller-Dombois and Ellenberg 1974). Concepts

such as succession, site, and environmental factors are all part of PNV. Existing vegetation is

simply what is there at the time of sampling. PNV classifications are based on existing vegetation.

succession and environmental factors (e.g., climate, geology, soil) considered together.

preferential sampling. Locating plots subjectively without preconceived bias (Mueller-Dombois

and Ellenberg 1974).

preprocessing. In mapping and remote sensing use, the group of processes typically completed

on an image before analysis or classification with the goal of improving the quality of the data.

Preprocessing operations may include geometric and radiometric corrections (Lachowski et al.

1996).

producer’s accuracy. An accuracy measure based on omission error as shown in the error

matrix. The producer’s accuracy is calculated by dividing the total number of correctly classified

sites of a certain category by the total number of sites surveyed in the same category (Lachowski

et al. 1996).

quantitative inventory. The objective quantification of the amount, composition, condition,

and/or productivity of resource types or parameters within specified levels of statistical precision.

(adapted from Helms 1998).

radiometric correction. In remote sensing, an image preprocessing technique that adjusts for

influence from scene illumination, atmospheric conditions, viewing geometry, and instrument

response characteristics (USDA Forest Service 1999).

raster data. Data organized in a grid of columns and rows. Raster data usually represent a planar

graph or geographical area (Lachowski et al. 1996).

reference data. (1) “Ground truth” data used in the image classification and accuracy assessment

processes and/or for direct image interpretation. Ground truth data are assumed to be “true”

information regarding surface features. In remote sensing projects, reference data serve two main

purposes: (a) reference data establish a link between variation on the ground and in the image

that is necessary for assigning image-modeling units (pixels or regions) to discrete land cover

classes in the image classification process; and (b) reference data help assess the accuracy of a

map. (2) Any secondary data that support the primary remote sensing data and thus may include

the ancillary data used to classify the image (adapted from Lachowski et al. 1996). 
Existing Vegetation Classification & Mapping Technical Guide 5-13

reflectance. The total solar energy incident on a given feature minus the energy that is either

absorbed or transmitted by the feature. Reflectance is dependent on the material type and condition,

and allows different features in a visual image to be distinguished (Lachowski et al. 1996). 

relative composition. List of the proportions of each plant species relative to the total amount of

all species present in a given area or stand (FGDC 1997, Jennings et al. 2004).

remote sensing. (1) The gathering of data regarding an object or phenomenon by a recording

device (sensor) that is not in physical contact with the object or phenomenon under observation

(Lachowski et al. 1996). (2) The science and art of obtaining information about an object, area,

or phenomenon through the analysis of data acquired by a device that is not in contact with the

object, area, or phenomenon under investigation (Lillesand and Kiefer 1987).

representative sampling. Systematic or random location of plots within strata; rejection criteria

may be necessary, however, to avoid sampling obvious ecotones, which are of limited use for

classifying vegetation. The gradsect technique or gradient directed sampling is one example of this

approach (Austin and Heylingers 1991, as cited in Jennings et al. 2004). The gradsect technique

is a form of stratified random sampling that may be cost effective for sampling vegetation patterns

along environmental gradients (Gillison and Brewer 1985). See also gradsect technique.

resolution. The minimum difference between two independently measured or computed values

that can be distinguished by the measurement or analytical method being considered or used

(USDA Forest Service 2004c).

resource mapping. The delineation of the geographic distribution, extent, and landscape patterns

of resource types or attributes.

scale. (1) The relationship between a distance on a map and the corresponding distance on the

Earth. For example, a scale of 1:24,000 means that 1 unit of measure on the map equals 24,000

of the same units on the Earth’s surface (Helms 1998). (2) Ecology, the level of spatial resolution

perceived or considered (Helms 1998). (3) In general, the degree of resolution at which ecological

processes, structures, and changes across space and time are observed and measured (USDA

Forest Service 1993). 

scientific classification. See natural classification.

sensor. A device that records electromagnetic radiation or other data about an object and presents

it in a form suitable for obtaining information about the environment (Lachowski et al. 1996).

series. In vegetation classification, an aggregation of taxonomically related plant associations

that takes the name of climax species that dominate the principle layer; a group of associations or

habitat types with the same dominant climax species. Conceptually a series is analogous to an

alliance; the series is a PNV concept (adapted from Driscoll et al. 1984).

shrubs. Woody plants that generally exhibit several erect, spreading, or prostrate stems and have

a bushy appearance. In instances where life form cannot be determined, woody plants less than

5 meters in height are considered shrubs (FGDC 1997).
5-14 Existing Vegetation Classification & Mapping Technical Guide

site. An area delimited by fairly uniform climatic and soil conditions (similar to habitat).

spatial data. Data that record the geographic location and shape of geographic features and their

spatial relationships to other features (USDA Forest Service 2004c).

spatial resolution. The measure of sharpness or fineness in spatial detail.; determines the smallest

object that can be resolved by a given sensor, or the area on the ground represented by each pixel.

For digital imagery, spatial resolution corresponds to pixel size and may be understood as roughly

analogous to “grain” in photographic images (Helms 1998).

species. In biological classification, the category below genus and above the level of subspecies

and variety; the basic unit of biological classification (adapted from Lincoln et al. 1998).

spectral resolution. The dimension and number of specific bands (wavelength intervals) in the

electromagnetic spectrum that a sensor can detect (Lachowski et al. 1996).

stand. (1) The basic unit of mapping and inventory (Graves 1913). (2) A community, particularly

of trees, possessing sufficient uniformity regarding composition, age, spatial arrangement, or condition, to be distinguishable from adjacent communities, so forming a silvicultural or management

entity (Ford-Robertson 1971). In the context of the protocol supported by this technical guide,

the terms “patch” and “stand” may be synonymous depending on the degree that management

considerations are incorporated into stand delineations along with compositional and structural

characteristics.

stratum. In general, one of a series of layers, levels, or gradations in an ordered system. In the

natural environment, the term is used in the sense of (1) a region of sea, atmosphere, or geology

that is distinguished by natural or arbitrary limits, or (2) a layer of vegetation, usually of the

same or similar height (adapted from FGDC 1998).

structure. (1) The spatial arrangement of the components of vegetation (Lincoln et al. 1998). (2)

A function of plant size and height, vertical stratification into layers, and horizontal spacing of

plants. Physiognomy refers to the general appearance of the vegetation; structure describes the

spatial arrangement of plants in more detail. Do not confuse physiognomy and structure

(Mueller-Dombois and Ellenberg 1974).

succession. Partial or complete replacement of one community by another (Daubenmire 1978).

successive refinement. The basic working approach of community ecologists; involves repeated

cycles of knowledge, questions, and observations (Pfister and Arno 1980, Gauch 1982).

supervised classification. A method of image classification that depends on the direct involvement

of the analyst in the pattern recognition process. See also unsupervised classification (USDA

Forest Service 1999).

synthesis tables. Summaries of mean and constancy by species and by types in a table with

types across the top and species down the side. These are essential to compare between types.

The data are summed by type in a synthesis table; association tables present data by plots or

sample units. 
Existing Vegetation Classification & Mapping Technical Guide 5-15

tabular data. Data that describe things using characters and numbers formatted in columns and

rows (USDA Forest Service 2004c).

taxonomic unit (taxon [s.], taxa [pl.]). The basic set of classes or types that comprise a classification. Taxonomic units can be developed for physiognomic classifications (e.g., tree dominated

classes or shrub dominated classes), floristic classifications (e.g., dominance type classes or plant

association classes), and they can be developed for structural classifications (e.g., canopy cover

classes and/or tree size classes). Taxonomic units represent a conceptual description of ranges

and/or modal conditions in vegetation characteristics. A taxonomic unit (or taxon) is a class

developed through the scientific classification process, or a class that is part of a taxonomy (USDA

Soil Survey Division 1999).

technical classification (or technical grouping). A classification in which the differentiating

characteristics are selected “for a specific, applied, practical purpose” (Buol et al. 1973, Pfister

and Arno 1980).

temporal resolution. A measure of how often a given sensor obtains imagery of a particular

area, also called coverage. For satellite data, temporal resolution depends on the satellite’s orbit

schedule and off-nadir pointing capability. Temporal resolution is important for projects requiring

multitemporal imagery, such as change detection projects (Lachowski et al. 1996).

thematic aggregation. The process of combining spatially distinct map features based on their

categorical similarity and spatial arrangement.

Thematic Mapper (TM). A sensor carried aboard Landsat 4 and 5. Data are collected in seven

electromagnetic spectral bands that were selected for vegetation analysis. Landsat 7also has a

panchromatic band with 15-meter spatial resolution; an onboard, full aperture, 5-percent absolute

radiometric calibration; and a thermal infrared channel with 60-meter spatial resolution (USDA

Forest Service 1999).

thematic resolution. The level of categorical detail present within a given map unit. In a general

sense, increased thematic resolution is represented by an increase in the number of map units and

conversely fewer map units for coarser thematic resolution. While thematic resolution is often

implied by geographic or spatial resolution, a direct relationship is not inherent (Helms 1998).

theme. Group of data that represent a place or thing such as soils, vegetation, or roads. A theme

may be less concrete, such as population density, school districts, or administrative boundaries

(USDA Forest Service 2004c).

theme (GIS). See layer.

training site. In mapping, the geographical area represented by the pixels in a training sample.

Usually, training sites have been previously identified through ground truth data or aerial photography. Also called training fields (Lachowski et al. 1996).

trees. Woody plants that generally have a single main stem and have more or less definite

crowns. In instances where life form cannot be determined, woody plants at least 5 meters in

height are considered trees (FGDC 1997).
5-16 Existing Vegetation Classification & Mapping Technical Guide

unsupervised classification. In mapping, a computer-automated method of spectral pattern

recognition in which some parameters are specified by the user and used to uncover statistical

patterns inherent in the image data. See also supervised classification (USDA Forest Service

1999).

user’s accuracy. In reference to accuracy assessment, an accuracy measure based on a commission

error in the error matrix. Also known as reliability, user’s accuracy is the probability that pixels

classified on the map actually represent the category on the ground. User’s accuracy is calculated

by dividing the total number of correctly classified sites of a certain category by the total number

of the certain category classified by the map (Lachowski et al. 1996).

vascular plant. Plant with water and fluid conductive tissue (xylem and phloem); includes seed

plants, ferns, and fern allies (FGDC 1997).

vector data. Data that represents physical forms (elements) such as points, lines, and polygons.

In terms of GIS, vectors typically represent a boundary between spatial objects (Lachowski et al.

1996).

vegetated. Areas having at least 1 percent or more of the land or water surface with live vegetation

cover at the peak of the growing season (FGDC 1997). 

vegetation complexes. Map units that comprise a grouping of dissimilar alliances that are spatially

and ecologically related on the landscape (called ecological complex in GAP Bulletin 7,

Brackney and Jennings 1998). 

vegetation cover. Vegetation that covers or is visible at or above the land or water surface; a

subcategory of earth cover. The percentage of the ground covered by a vertical projection of the

outermost perimeter of the natural spread of the foliage of plants (FGDC 1997).

vegetation data. The attributes of the vegetation that are used to classify and characterize the

vegetation type and to map vegetation stand. These data come from the interpretation of remotely

sensed imagery, fieldwork, and other thematic data sources (FGDC 1997).

vegetation mapping. The process of delineating the geographic distribution, extent, and landscape

patterns of vegetation types based on composition, physiognomy, and structure.

vegetation type. A named class of plant community or vegetation defined on the basis of selected

shared floristic, physiognomic, and/or structural characteristics that distinguish it from other

classes of plant communities or vegetation. 

vertical. At right angles to the horizontal; includes altitude and depth (FGDC 1998).
Existing Vegetation Classification & Mapping Technical Guide 6-1

List of Abbreviations and Acronyms

AEUI Aquatic Ecological Unit Inventory

ASPRS American Society of Photogrammetry and Remote Sensing

CALVEG Classification and Assessment with Landsat of Visible Ecological Groupings

CFR Code of Federal Regulations

CISC Continuous Inventory of Stand Conditions

CSDGM Content Standard for Digital Geospatial Metadata

CSE Common Stand Exam

CVU Common Vegetation Unit

CWHR California Wildlife Habitat Relationships

d.b.h. diameter at breast height

DEM digital elevation model

ESA Ecological Society of America

FHM Forest Health Monitoring

FIA Forest Inventory Analysis

FSH Forest Service Handbook

FSM Forest Service Manual

FGDC Federal Geographic Data Committee

GAP Gap Analysis Project

GIS Geographic Information System

GPS Global Positioning System

ICEC International Classification of Ecological Communities

lidar Light detection and ranging

MLRA Major Land Renewable Resource Areas

MMU minimum map unit

MODIS Moderate Resolution Imaging Spectroradiometer

MSS Multispectral Scanner

NDVI Normalized Difference Vegetation Index

NFMA National Forest Management Act of 1976

NFS National Forest System

NGDC National Spatial Data Infrastructure

RCS Natural Resources Conservation Service

NRI National Research Institute

NRIS Natural Resource Information System

NSDI National Spatial Data Infrastructure

NSSDA National Standard for Spatial Data

NVC National Vegetation Classification
6-2 Existing Vegetation Classification & Mapping Technical Guide

NVCS National Vegetation Classification Standard

NWI National Wetlands Inventory

OMB Office of Management and Budget

PCA Principal Component Analysis

PNV Potential Natural Vegetation

PRISM Parameter-elevation Regressions on Independent Slopes Model

R1 Region 1, USDA Forest Service, Northern Region

R2 Region 2, USDA Forest Service, Rocky Mountain Region

R8 Region 8, USDA Forest Service, Southern Region

RMSE root-mean-square data

RPA Forest and Rangeland Resources Planning Act of 1974

SAF Society of American Foresters

SILC Satellite Image Land Classification

SRM Society for Range Management

TES Threatened and Endangered Species

TEUI Terrestrial Ecological Unit Inventory

USDA U.S. Department of Agriculture

U.S.C. United States Code

USGS U.S. Geological Survey

VPF Vector Product Format

VSS Vegetation Stand Structure
Existing Vegetation Classification & Mapping Technical Guide 1A-1

Appendix 1A. 

Federal Geographic Data Committee Guiding Principles for

Vegetation Classification

This appendix was taken from Federal Geographic Data Committee (FGDC),Vegetation

Subcommittee. 1997. Vegetation classification standard. FGDC-STD-005. Reston, VA:

Federal Geographic Data Committee, U.S. Geological Survey. http://www.fgdc.gov/standards/documents/standards/vegetation/vegclass.pdf.

The guiding principles for the Federal Geographic Data Committee’s National

Vegetation Classification Standards (NVCS) (FGDC 1997) are listed below. Italics indicate

goals that have not been fully achieved to date. Revision of the physiognomic classification standard and completion of the floristic classification methodology standard will

address most of these goals.

1. The classification is applicable over extensive areas.

2. The vegetation classification standard is compatible, wherever possible, with other

earth cover/land cover classification standards.

3. The classification will avoid developing conflicting concepts and methods through

cooperative development with the widest possible range of individuals and institutions.

4. Application of the classification must be repeatable and consistent.

5. When possible, the classification standard will use common terminology (i.e., terms

should be understandable and jargon should be avoided).

6. For classification and mapping purposes, the classification categories were

designed to be mutual exclusive and additive to 100 percent of an area when

mapped within any of the classification’s hierarchical levels (Division, Order, Class,

Subclass, [Group], Subgroup, Formation, Alliance, or Association). Guidelines have

been developed for those instances where placement of a floristic unit into a single

physiognomic classification category is not clear. Additional guidelines will be

developed as other such instances occur.

7. The classification standard will be dynamic, allowing for refinement as additional

information becomes available.

8. The NVCS is of existing, not potential, vegetation and is based upon vegetation

condition at the optimal time during the growing season. The vegetation types are

defined on the basis of inherent attributes and characteristics of the vegetation

structure, growth form, and cover.

9. The NVCS is hierarchical (i.e., aggregatable) to contain a small number of generalized

categories at the higher level and an increasingly large number of more detailed categories

at the lower levels. The categories are intended to be useful at a range of scales.
1A-2 Existing Vegetation Classification & Mapping Technical Guide

10. The upper levels of the NVCS are based primarily on the physiognomy (life form,

cover, structure, leaf type) of the vegetation (not individual species). The life forms

(e.g., herb, shrub, or tree) in the dominant or uppermost stratum will predominate in

the classification of the vegetation type. Climate and other environmental variables

are used to help organize the standard, but physiognomy is the driving factor.

11. The lower levels of the NVCS are based on actual floristic (vegetation) composition.

The data used to describe alliance and association types must be collected in the field

using standard and documented sampling methods. The alliance and association units

are derived from these field data. These floristically based classes will be nested

under the physiognomic classes of the hierarchy.
Existing Vegetation Classification & Mapping Technical Guide 1B-1

Appendix 1B. 

National Vegetation Classification Standards 

Physiognomic Hierarchy Overview

The quoted material contained in this appendix was taken from Federal Geographic Data

Committee (FGDC),Vegetation Subcommittee. 1997. Vegetation classification standard.

FGDC-STD-005. Reston, VA: Federal Geographic Data Committee, U.S. Geological Survey.

http://www.fgdc.gov/standards/documents/standards/vegetation/vegclass.pdf. 

Unquoted material contained in this appendix was provided by David Tart, Regional

Vegetation Ecologist, USDA Forest Service, Intermountain Region.

The FGDC National Vegetation Classification Standards (NVCS) (1997) establishes a

hierarchical vegetation classification with nine levels. The top seven levels are primarily

based on physiognomy. The two lowest levels, alliance and association, are based on

floristic attributes. The seven physiognomic levels are described below. These descriptions

include the FGDC definition of the level, classification criteria, and any issues implementation that have hampered implementation of the physiognomic classification standard.

1. Division. “The first level in the classification standard separating Earth cover 

into either vegetated or non-vegetated categories” (FGDC 1997).

Classification Criteria: The Vegetated Division is defined as “Areas having equal to

or greater than 1 percent or more of the land or water surface with live vegetation

cover at the peak of the growing season” (FGDC 1997). Areas with less than 1 percent

live vegetation comprise the Nonvegetated Division. The Nonvegetated Division is

subdivided no further. The remaining levels of the physiognomic hierarchy are all

subdivisions of the Vegetated Division.

Implementation Issues: Detection of 1 percent vegetation through remote sensing is

not feasible. The Multi-Resolution Landscape Characterization (MRLC) 2000 proposed land cover classes define Barren as less than 20 percent vegetation cover.

2. Order. “The next level in the hierarchy under Division. The Orders within the

Vegetated Division are generally defined by dominant life form (tree, shrub, dwarf

shrub, herbaceous, non-vascular)” (FGDC 1997).

Classification Criteria: Orders are classified based on the dominant life form or

tallest life form with at least 25-percent canopy cover. They are based predominantly

on vegetation structure.
1B-2 Existing Vegetation Classification & Mapping Technical Guide

Implementation Issues: The Nonvascular Dominated Order does not include crustose

lichens, which are essentially regarded on non-living at this level of the classification.

This has no ecological meaning and appears to represent a bias toward what can be

detected through remote sensing.

3. Class. “A level in the classification hierarchy defined by the relative percent canopy

cover of the tree, shrub, dwarf shrub, herb, and nonvascular life forms in the uppermost strata during the peak of the growing season” (FGDC 1997).

Classification Criteria: Classes are based on the following structural attributes:

• Tree canopy cover

• Shrub height and canopy cover

• Herbaceous vs. nonvascular canopy cover

Implementation Issues: Only two of the five orders are subdivided at the class level,

the Tree Dominated and Shrub Dominated Orders. These divisions, based on tree

canopy cover and shrub height, have proved impractical in several classification and

mapping projects. Thus, the Order and Class levels may be merged when the physiognomic hierarchy is revised (FGDC 2001a).

4. Subclass. “A level in the classification determined by the predominant leaf phenology

of woody plants or the leaf type and periodicity of herbaceous plants” (FGDC 1997).

Classification Criteria: Subclasses are based on the following life form attributes:

• Leaf phenology (e.g., evergreen vs. deciduous)

• Gross morphology (e.g., graminoid vs. forb)

• Herb periodicity (e.g., annual vs. perennial)

5. Group. “A level of the classification defined by a combination of climate, leaf 

morphology, and leaf phenology” (FGDC 1997).

Classification Criteria: Groups are based on the following life form, structural, and

abiotic attributes:

• Climatic Regime (e.g., temperate, tropical, subpolar)

• Leaf morphology (e.g., extremely xeromorphic)

• Leaf phenology (e.g., cold- vs. drought-deciduous)

• Presence of a sparse woody layer in grasslands.

Implementation Issues: Climatic regime is not a vegetation attribute, so its use violates FGDC guiding principle number 8 (see Appendix 1A). Additionally, climatic

regime cannot be assessed in a one-time visit to a plot.
Existing Vegetation Classification & Mapping Technical Guide 1B-3

6. Subgroup. “A level of the hierarchy that splits Natural/Semi-Natural vegetation

types from the Planted/Cultivated vegetation types” (FGDC 1997).

Classification Criteria: Subgroups are based on the following definitions:

Natural/Seminatural. Areas dominated by native or established vegetation that

has not been cultivated or treated with any annual management or manipulation

regime. In cases where it cannot be assessed whether the vegetation was planted

or cultivated by humans, the vegetation is considered “Natural/Semi-Natural.”

Planted/Cultivated. Areas dominated with vegetation which has been planted

in its current location by humans and/or is treated with annual tillage, a modified

conservation tillage, or other intensive management or manipulation. The majority

of vegetation in these areas is planted and/or maintained for the production of

food, feed, fiber, or seed.

Implementation Issues: These definitions have proved problematic, particularly in

forest plantations of native tree species. The ESA Vegetation Classification Panel has

deferred on this issue, stating, “...at this time, no standards for defining naturalness

are proposed” (Jennings et al. 2002).

7. Formation. “A level of the hierarchy based on ecological groupings of vegetation

units with broadly defined environmental and additional physiognomic factors in

common. This level is subject to revision as the vegetation Alliances and Associations

are organized under the upper levels of the hierarchy” (FGDC 1997).

Classification Criteria: Formations are based on the following life form, structural,

and abiotic attributes:

• Elevation zone (e.g., alpine, submontane)

• Flooding regime (Cowardin 1979)

• Leaf morphology (e.g., xeromorphic)

• Tree crown shape (e.g., cylindrical)

• Presence of sparse tree layer in shrublands

• Leaf phenology and morphology of sparse tree layer in shrublands

• Leaf phenology and morphology of sparse woody layer in grasslands

• Shrub growth form (e.g., suffruticose, cushion, mat)

• Presence of succulents in shrublands

• Leaf phenology of shrubs (e.g., facultative-deciduous)

• Plant height in herbaceous vegetation

• Graminoid rooting habit (e.g., sod-forming vs. bunch)
1B-4 Existing Vegetation Classification & Mapping Technical Guide

Implementation Issues: The plethora of attributes used to define formations has produced many types that are not mutually exclusive based on their names. Since no

diagnostic key has been written for formations, consistently assigning plots or associations to formations is impossible. 

Elevation zones and flooding regime cannot be determined during a one-time plot

visit. Recognition of elevation zones as defined by the FGDC (1997) requires a spatial

analysis of vegetation patterns following completion of the classification of associations

and alliances. Thus, it is impractical to use elevation zone as a top-down classification

criterion. Flooding regimes reflect average or modal growing season conditions over

several years, which cannot be practically evaluated in the field.
Existing Vegetation Classification & Mapping Technical Guide 1C-1

Appendix 1C.

Draft Key to Federal Geographic Data Committee 

Physiognomic Subclass

This appendix was developed by David Tart, Regional Vegetation Ecologist, USDA

Forest Service, Intermountain Region, August 2002.

This key is not a product of, nor is it endorsed by, the FGDC Vegetation

Subcommittee. It was written to improve the author’s understanding of the FGDC physiognomic hierarchy and to facilitate comparison of the Society of American Foresters

and Society for Range Management cover types to the FGDC Vegetation Classification

Standard (FGDC-STD-005). FGDC-STD-005 indicates that a simple dichotomous key to

the standard will be developed as part of testing and validating the physiognomic levels,

but such a key has not yet been completed. It is hoped that this key can serve as a starting

point for achieving that objective.

This key identifies the following levels of the 1997 FGDC vegetation hierarchy:

Division, Order, Class, and Subclass. It is designed to be used in conjunction with the

Vegetation Classification Standard (FGDC-STD-005) published by the Vegetation

Subcommittee of the Federal Geographic Data Committee in June, 1997. That document

should be used together with this key to identify physiognomic vegetation types. The key

is followed by a list of the natural/seminatural vegetation types in the physiognomic

hierarchy, by level, from Division to Subclass.

Instructions for Using the Key

The key is arranged by physiognomic hierarchy level. Divisions (Vegetated and

Nonvegetated) are identified first. The rest of the key pertains only to the Vegetated

Division. Orders within the Vegetated Division are keyed out first, followed by Classes

within each Order and Subclasses within each Class. 

The key is dichotomous, with couplets of two leads each (for example, 1a and 1b).

Choose the couplet that best fits the plot or stand you are trying to assign to a physiognomic type. Each choice will lead you to either the name of a vegetation type or to

another couplet. Names of Orders and Classes are followed by a number in parentheses.

This number indicates the couplet where the key to the next level of the hierarchy

begins. For example, Shrub Dominated Order is followed by (12) in lead 5a, indicating

that the key to Classes within the Shrub Dominated Order begins at couplet 12. The

code for each vegetation type is listed at the right-hand margin of the key. However, no

codes have been established for the Division and Order levels of the hierarchy.

Terminology in the key follows the FGDC Vegetation Classification Standard (FGDC

1997) cited above. The glossary in that document should be consulted when using the key. 
1C-2 Existing Vegetation Classification & Mapping Technical Guide

List of FGDC Vegetation Types

The List of FGDC Vegetation Types (p. 10) uses the following conventions:

• The list is arranged by hierarchy level and code. All Divisions are listed first, 

followed by all the orders, etc.

• Italicized codes and names indicated types that have not yet been identified in the

United States. (e.g., IVC Mixed evergreen-deciduous dwarf-shrubland Subclass on

p. 10)

Caveats and Disclaimers

As noted above, this key has not been produced or approved by the FGDC Vegetation

Subcommittee. The author accepts sole responsibility for any errors in this key.

Key to FGDC Existing Vegetation Hierarchy

Code

1a. Vegetation cover <1% ..........................................Non-Vegetated Division

1b. Vegetation cover >1%............................................Vegetated Division (2)

Key to Orders (Within the Vegetated Division)

2a. Vegetation cover excluding crustose 

lichens < 10%............................................No Dominant Life Form Order VII 

= Sparse Vegetation Class (27)

2b. Vegetation cover excluding crustose lichens >10% .....................................3

3a. Total tree (woody plants > 5m tall) 

canopy cover > 25% ..............................Tree Dominated Order (11) 

3b. Total tree canopy cover < 25% ........................................................4

4a. Shrub (woody plants > 0.5m tall), 

dwarf-shrub (woody plants < 0.5m tall), 

herb, and nonvascular plant cover each 

less than tree cover..........................................Tree Dominated Order (11)

4b. Shrub, dwarf-shrub, herb, and/or nonvascular 

plant cover greater than tree cover............................................................5

5a. Total shrub (woody plants > 0.5m tall) 

canopy cover > 25% ............................Shrub Dominated Order (12)

5b. Total shrub canopy cover <25% .....................................................6

6a. Dwarf-shrub (woody plants<0.5m tall), 

herb, and nonvascular plant cover each 

less than shrub cover ....................................Shrub Dominated Order (12)
Existing Vegetation Classification & Mapping Technical Guide 1C-3

Code

6b. Dwarf-shrub, herb, and/or nonvascular plant 

cover greater than shrub cover..................................................................7

7a. Total dwarf-shrub (woody plants<0.5m tall) 

canopy cover > 25% ............................Shrub Dominated Order (12)

7b. Total dwarf-shrub cover < 25% .......................................................8

8a. Herb and nonvascular plant cover each 

less than dwarf-shrub cover..........................Shrub Dominated Order (12)

8b. Herb and/or nonvascular plant cover 

greater than dwarf-shrub cover .................................................................9

9a. Total herb cover > 25%.................................Herb Dominated Order

= Herbaceous Vegetation Class (22) V

9b. Total herb cover < 25%..................................................................10

10a. Herb cover greater than total cover of 

bryophytes, noncrustose lichens, and alga ............Herb Dominated Order

= Herbaceous Vegetation Class (22) V

10b. Herb cover less than total cover of bryophytes, 

noncrustose lichens, and alga ....................Nonvascular Dominated Order

= Nonvascular Vegetation Class (25) VI

Keys to Classes

Key to Classes Within the Tree Dominated Order

11a. Total tree canopy cover > 61% ................Closed Tree Canopy Class (14) I

11b. Total tree canopy cover < 61% ...................Open Tree Canopy Class (16) II

Key to Classes Within the Shrub Dominated Order

12a. Total shrub (woody plants > 0.5m tall) 

canopy cover > 25%..................................................Shrubland Class (18) III

12b. Total shrub canopy cover < 25% ...........................................................13

13a. Shrub canopy cover > dwarf-shrub 

(woody plants < 0.5m tall) canopy cover.........Shrubland Class (18) III

13b. Shrub canopy cover < dwarf-shrub 

canopy cover..........................................Dwarf-shrubland Class (20) IV
1C-4 Existing Vegetation Classification & Mapping Technical Guide

Keys to Subclasses

Code

Key to Subclasses Within the Closed Tree Canopy Class

14a. Evergreen species contribute > 75% 

of the total tree cover ................................Evergreen Closed Tree Canopy IA

14b. Evergreen species contribute < 75% 

of the total tree cover ..............................................................................15

15a. Deciduous species contribute > 75% 

of the total tree cover ......................Deciduous Closed Tree Canopy IB

15b. Deciduous species contribute < 75% 

of the total tree cover...............Mixed Evergreen-Deciduous Closed

Tree Canopy IC

Key to Subclasses Within the Open Tree Canopy Class

16a. Evergreen species contribute > 75% 

of the total tree cover ..................................Evergreen Open Tree Canopy IIA

16b. Evergreen species contribute < 75% 

of the total tree cover ..............................................................................17

17a. Deciduous species contribute > 75% 

of the total tree cover.........................Deciduous Open Tree Canopy IIB

17b. Deciduous species contribute < 75% 

of the total tree cover .................Mixed Evergreen-Deciduous Open

Tree Canopy IIC

Key to Subclasses Within the Shrubland Class

18a. Evergreen species contribute > 75% 

of the total shrub cover .............................................Evergreen Shrubland IIIA

18b. Evergreen species contribute < 75% 

of the total shrub cover ...........................................................................19

19a. Deciduous species contribute > 75% 

of the total shrub cover....................................Deciduous Shrubland IIIB

19b. Deciduous species contribute < 75% 

of the total shrub cover.......Mixed Evergreen-Deciduous Shrubland IIIC

Key to Subclasses Within the Dwarf-Shrubland Class

20a. Evergreen species contribute > 75% 

of the total dwarf-shrub cover .......................Evergreen Dwarf-Shrubland IVA
Existing Vegetation Classification & Mapping Technical Guide 1C-5

Code

20b. Evergreen species contribute < 75% 

of the total shrub cover ...........................................................................21

21a. Deciduous species contribute > 75% 

of the total dwarf-shrub cover..............Deciduous Dwarf-Shrubland IVB

21b. Deciduous species contribute < 75% 

of the total dwarf-shrub cover..............Mixed Evergreen-Deciduous

Dwarf-Shrubland IVC

Key to Subclasses Within the Herbaceous Vegetation Class (Herb Dominated Order)

22a. Non-emergent herbs structurally 

supported by water and rooted

in substrate contribute > 50% 

of total herbaceous canopy ...................Hydromorphic Rooted Vegetation VC

22a. Non-emergent herbs structurally 

supported by water and rooted

in substrate contribute < 50% 

of total herbaceous canopy .....................................................................23

23a. Perennial graminoids contribute > 50% 

of total herbaceous canopy .............Perennial Graminoid Vegetation VA

23b. Perennial graminoids contribute < 50% 

of total herbaceous canopy.............................................................24

24a. Perennial forbs, including ferns and biennials, contribute > 50% 

of total herbaceous canopy ................................Perennial Forb Vegetation VB

24b. Perennial forbs, including ferns and biennials, contribute < 50% 

of total herbaceous canopy.......................................Annual Graminoid or 

Forb Vegetation VD

Key to Subclasses Within the Nonvascular Vegetation Class (Nonvascular

Dominated Order)

25a. Bryophytes generally dominate the 

nonvascular plant cover ...........................................Bryophyte Vegetation VIA

25b. Bryophytes do not dominate the nonvascular plant cover ......................26

26a. Foliose or fruticose lichens generally 

dominate the nonvascular plant cover...................Lichen Vegetation VIB

26b. Foliose or fruticose lichens do not 

dominate the nonvascular plant cover ......................Alga Vegetation VIC
1C-6 Existing Vegetation Classification & Mapping Technical Guide

Key to Subclasses Within the Sparse Vegetation Class (Vegetation Not Dominant Order)

27a. Vegetation characterized by plants growing 

in fissures of, or growing adnate on cliffs, 

level to gently sloping bedrock, or pahoehoe 

lava flows ........................................Consolidated Rock Sparse Vegetation VIIA

27b. Vegetation not characterized by plant

growing on consolidated rock substrates................................................28

28a. Vegetation characterized by plants 

growing in or on boulder to 

gravel-sized substrates .................Boulder, Gravel, Cobble, or Talus

Sparse Vegetation VIIB

28b. Vegetation not characterized by 

plants growing on gravel-sized or 

larger substrates ............Unconsolidated Material Sparse Vegetation VIIC
Existing Vegetation Classification & Mapping Technical Guide 1C-7

List of FGDC Vegetation Types by Hierarchical Level

Italics indicate a type that has not yet been identified in the United States.

Level Code Name

Division — Nonvegetated

— Vegetated

Order — Tree Dominated

— Shrub Dominated

— Herbaceous Dominated

— Nonvascular Dominated

— No dominant life form

Class I Closed Tree Canopy

II Open Tree Canopy

III Shrubland

IV Dwarf Shrubland

V Herbaceous Vegetation

VI Nonvascular Vegetation

VII Sparse Vegetation

Subclass IA Evergreen closed tree canopy

IB Deciduous closed tree canopy

IC Mixed evergreen—deciduous closed 

tree canopy

IIA Evergreen open tree canopy

IIB Deciduous open tree canopy

IIC Mixed evergreen—deciduous open 

tree canopy

IIIA Evergreen shrubland

IIIB Deciduous shrubland

IIIC Mixed evergreen—deciduous 

shrubland

IVA Evergreen dwarf-shrubland

IVB Deciduous dwarf-shrubland
1C-8 Existing Vegetation Classification & Mapping Technical Guide

Level Code Name

Subclass (continued) IVC Mixed evergreen—deciduous dwarfshrubland 

VA Perennial graminoid vegetation

VB Perennial forb vegetation

VC Hydromorphic rooted vegetation

VD Annual graminoid or forb vegetation

VIA Bryophyte vegetation

VIB Lichen vegetation

VIC Alga vegetation

VIIA Consolidated rock sparse vegetation

VIIB Boulder, gravel, cobble, or talus 

sparse vegetation

VIIC Unconsolidated material sparse 

vegetation
Existing Vegetation Classification & Mapping Technical Guide 2A-1

Appendix 2A.

Example Field Forms and Instructions

This appendix includes examples of forms for recording plot metadata, environmental

attributes, and vegetation data for ocular macroplots (see section 2.4).

2A.1 Instructions for General Site Data Form

Collect the following data elements at all sample sites. R = required; O = optional.

Field Name Instructions

Site ID R Record a plot number or site identifier unique within the project. 

Project Name R Record the name of the project.

Date R Record the month, day, and year in the format MMDDYYYY.

Sample Type(s) R Record the type(s) of data collected on the plot using the following codes:

OCMA = Ocular Macroplot; FLLI = Flora Line Intercept 

FLCO = Flora Cover/Frequency; FLPO = Flora Point Cover

FLTR = Flora Tree Data; SOPE = Soil Pedon (Individual tree measurements)

Examiner(s) R Record the last name, first name, and middle initial of all crewmembers. Record the name of the principal 

investigator first.

Plot Location Type R Record the approach used to locate the plot using the following codes:

P = Preferential 

R = Random

S = Stratified Random (or systematic)

See section 2.3 of the technical guide for a discussion of sampling strategies.

Species List Type R Record the completeness of the plant species list for the plot using the following codes:

C = Complete—All plant species present at time of sampling are recorded.

R = Reduced—Not all plant species are recorded. The list may be limited by a cover threshold (e.g., > 5% cover) or 

relative abundance (e.g., five most abundant species).

S = Selected—Not all plant species recorded. A protocol- or project-specific list of species are recorded whenever 

they are present on a plot.

L = Lifeform Only—No species are recorded. Cover is only recorded for life forms, and usually by layer or size 

class within life form.

A complete species list is required for developing and describing new associations and alliances. See section 2.43 of 

the technical guide for more information.

Plot Area R Record the area of the macroplot or belt transect in either acres or square meters, and the unit of measure 

(UOM) used. See section 2.41 of the technical guide for guidelines for determining plot size.

Plot Size R Record actual plot dimensions. Radius for circular plots; width and length for rectangular plots. Also record the 

UOM used.

Vegetation R Record as much classification information as known at the time of sampling including the potential natural

Classification vegetation (PNV) series, association, and reference; existing vegetation alliance, association and reference; 

ecological type; and FGDC Subclass. Subclass is determined in the field using the key in Appendix 1C.
2A-2 Existing Vegetation Classification & Mapping Technical Guide

Field Name Instructions

GPS Location R Record the location of the sample site using latitude-longitude or UTM with zone.

Aerial Photo ID O Record the photo identification number.

Flight Line O Record the three-digit photo flight line.

Roll # O Record the three-digit roll number and contract fiscal year. For example, “189” identifies roll 1 taken in fiscal 

year 1989.

Plot Photo Label O Record a descriptive alpha/numeric label to track photos. Example is roll number followed by exposure # “2-14” 

to help label and track photos after processing.

Photo Description O Record a description of the photo subject.

Film Type O Record the type of film when a film camera is used.

Digital Photo O When a digital camera is used, record the filename of the photo.

File Name

Elevation R Record the sample site elevation in feet, to the nearest 10 feet.

Slope R Record the sample site average slope, in percent.

Aspect R Record the sample site aspect in degrees. For slopes that have no aspect, record a zero. 

For due north, record 360.

Horizontal Slope O Record the horizontal shape of the plot. See appendix section 2A.11 and figure 2A.1 for values and codes.

Shape

Vertical Slope O Record the vertical shape of the plot. See appendix section 2A.11 and figure 2A.1 for values and codes.

Shape

Slope Complexity O Record the slope complexity of the plot using the following codes:

S = Simple = Linear, convex, or concave in shape.

C = Complex = Broken, undulating, or patterned in shape.

Slope Position R Record the two-dimensional position of the plot on the landform using the following codes:

SU = Summit; SH = Shoulder; BS = Backslope

FS = Footslope; TS = Toeslope

Slope Position R Record the modifier which best describes the primary slope position using the following codes: 

Modifier LR = Lower; MD = Mid; UP = Upper

Ground Surface R Record each ground surface cover type present in the plot. See appendix sections 2A.12 and 2A.13 for types,

Cover Type descriptions, and codes.

Ground Surface R Record an ocular estimate of the percentage of the plot covered by each ground surface cover type.

Cover Percent

Disturbance Type O Record major disturbance events. See section 2A.14 in this appendix for a list of disturbance types and codes. 

Disturbance O Record the vegetation affected and/or the ground cover affected in percent.

Extent Affected

Disturbance Date O Record the disturbance date in years, to the nearest year.
Existing Vegetation Classification & Mapping Technical Guide 2A-3

2A.1.1 Vertical and Horizontal Shape Code 

The following codes should be used for vertical and horizontal slope shape.

Some of the slope shapes are illustrated in figure 2A.1.

Code Description

BR Broken—cliffs, knobs, and/or benches interspersed with steeper slopes; 

generally characterized by sharp, irregular breaks.

CV Convex—raised, arched up, curved out.

LI Linear/Planar—straight, even, or smooth.

CC Concave—depressional, curved in.

UN Undulating (also rolling)—pattern of one or more low relief ridges or 

knolls and draws.

PA Patterned—relief of hummocks and swales with several feet. 

FL Flat—straight and level.

XX Unable to assess

Figure 2A.1. Vertical and horizontal slopes.

2A.1.2 Ground Surface Cover

Ground surface cover estimates are ocular. Absolute percent cover of the fixed area plot

is the standard and is required. Ground surface cover is defined as the percent of plot

surface area occupied by the ground cover type. Estimate to the nearest 1 percent in the

1–10 percentage range, to the nearest 5 percent for amounts exceeding 10 percent.

Figure 2A.2 illustrates some ground cover types. The table on page 2A-4 is a reduced

set of ground cover categories used in existing vegetation classification to describe and

develop interpretations for ground cover and document disturbance effects.
2A-4 Existing Vegetation Classification & Mapping Technical Guide

Code Description

BARE Bare soil: Soil particles < 2 mm not covered by rock, cryptogams, or organic 

material. Does not include any part of a road, but does include foot trails.

Live vegetation categories:

BAVE Basal vegetation: Basal vegetation is the soil surface occupied by live basal or root 

crown portion of vascular plants, including live trees. Typically ranges between 3–7%;

15 % is very high and rarely encountered.

NONV Nonvascular: Plants or plant-like organisms without specialized water or fluid 

conductive tissue (xylem and phloem). Includes mosses, liverworts, hornworts, 

lichens, algae, and bacterial soil crusts.

Organic debris categories:

LITT Litter: Plant litter and duff not yet incorporated into the decomposed top humus 

layer. Includes twigs < _ inch in diameter, ash from burned plants, dead nonvascular 

plants, and dung.

WOOD Wood: Any dead woody material > _ inch in diameter, small and large woody debris, 

regardless of depth. Includes bases of standing dead trees and shrubs.

Rock categories:

BEDR Bedrock: A general term for the rock, usually solid, that underlies soil or other 

unconsolidated, superficial material.

BOUL Boulders: Rock > 600 mm (24 inches) in diameter or length.

COBB Cobbles: Rock fragments between 75 and 250 mm (3 and 10 inches) in diameter.

GRAV Gravel: Rock fragments between 2 and 75 mm in diameter.

PAVE Pavement: A natural concentration of closely packed and polished stones at the soil 

surface in a desert (may or may not be an erosional lag). Or rock fragments 

< 19.1 mm in diameter.

ROCK Total Rock: Relatively hard, naturally formed mineral or petrified matter 

> 2 mm in diameter.

RROC Range Rock: Rock fragments > _ inch (19.1 mm) in diameter.

STON Stones: Rock fragments between 250 and 600 mm (10 and 24 inches) in diameter.

Miscellaneous categories:

PEIS Permanent Ice and Snow: Surface area covered by apparently permanent ice and/or 

snow at the time of plot measurement.

ROAD Road: Any road or vehicle trail that is regularly maintained or in long-term 

continuous use. Includes cutbanks and fills.

TRIS Transient Ice and Snow: Surface area covered by apparently transient ice and/or 

snow at the time of plot measurement. 

WATE Water: Includes transient water that obscures other cover types and permanent water 

where the water table is above the ground bogs, swamps, marshes, and ponds.

Figure 2A.2. Ground surface cover types.

Water Moss/Lichen Duff/Litter Basal Gravel-Boulder Wood Bare Groud Bed Rock

Basal
Existing Vegetation Classification & Mapping Technical Guide 2A-5

Rock Set 1 Rock Set 2 Rock Set 3

ROCK All rock from gravel PAVE Pavement GRAV Gravel (2–75 mm diam.)

to bedrock. (2–19.1 mm diam.) COBB Cobbles

RROC Rock (> 19.1 mm (75–250 mm diam.)

diam.) STON Stones (250–600 mm diam.)

BOUL Boulders (> 600 mm diam.)

BEDR Bedrock

Code Disturbance or Treatment Code Disturbance or Treatment

10000 Insects (General) 50003 Drought

10011 Ant (Formicidae) 50004 Flooding/High Water

11000 Bark Beetles 50011 Snow/Ice

12000 Defoliators 50013 Wind/Tornado

13000 Chewing Insects 50015 Avalanche

14000 Sucking Insects 50016 Mud/Landslide

15000 Boring Insects 51001 Channel Erosion

16000 Seed/Cone/Flower/Fruit Insects 51002 Soil Creep

17000 Gallmaker Insects 51010 Slump

18000 Insect Predators 70005 Land Clearing

19000 General Diseases 70006 Land Use Conversion

20000 Biotic Damage 70008 Mechanical

21000 Root/Butt Diseases 71000 Timber Harvest

22000 Stem Decay/Cankers 71002 Firewood Harvest

23000 Parasitic/Epiphytic Plants 71027 Natural Changes (No Cut)

23001 Mistletoe 73000 Regeneration Activities (General)

24000 Decline Complexes/Dieback/Wilts 73004 Seeding (Trees-Natural)

The following ground cover types should be recorded whenever they are present and are

included on the example General Site Data form: bare soil, basal vegetation, nonvascular, litter, and wood. More detailed subdivisions of these categories are available in the

Natural Resource Information System (NRIS), but are not recommended for vegetation

classification. The miscellaneous categories should also be recorded whenever present.

Rock cover must be recorded using one of the three sets of categories described below.

2A.1.3 Rock Ground Cover Types

Rock cover on the ground surface should be described using one of the following sets of

ground cover types. Set 1 is the minimum requirement. Set 3 is recommended for vegetation classification and description performed in conjunction with Terrestrial

Ecological Unit Inventory (TEUI). Set 2 is used primarily for specific rangeland monitoring methods.

2A.1.4 Disturbance Event Code Categories

The following codes should be used for disturbance and treatment types:
2A-6 Existing Vegetation Classification & Mapping Technical Guide

2A.2 Instructions for Vegetation Composition Form

The Vegetation Composition Form can be used to record or summarize data for a number

of sampling methods. The following describes its use for the ocular macroplot method.

2A.2.1 Vegetation Sampling Metadata

The first part of the Vegetation Composition Form records metadata about the vegetation

sampling methods and who collected the data. The plot location should be recorded on

the General Site Data Form. 

Code Disturbance or Treatment Code Disturbance or Treatment

25000 Foliage Diseases 73005 Seeding (Trees-Artificial)

26000 Stem Rusts 73008 Grass Seeding

27000 Broom Rusts 73015 Site Preparation

30000 Fire 73016 Brush Control

41002 Beaver 74000 Timber Stand Improvement (General—

Noncommercial)

41003 Big Game (e.g., Deer) 75000 Prescribe Burning (General)

41016 Browsing 75004 Planned Ignition—Prescribed Burn—

Natural Fuels

41021 Rodents 75005 Unplanned Ignition—Prescribed 

Burn—Natural Fuels

41022 Elk 78007 Miscellaneous Upland Recreation 

Activities

42001 Cattle 78008 Miscellaneous Riparian Recreation 

Activities

42004 Sheep 80000 Multidamage (Insects/Diseases)

90000 Unknown
Existing Vegetation Classification & Mapping Technical Guide 2A-7

General Site Data Form

USDA Forest Service
2A-8 Existing Vegetation Classification & Mapping Technical Guide

Field Name Instructions

Site ID R Record a plot number or site identifier that is unique within the project. This must match the Site ID on the 

General Site Data Form.

Date R Record the month, day, and year in the format MMDDYYYY.

Examiner(s) R Record the last name, first name, and middle initial of all crewmembers. Record the name of the principal 

investigator first.

Sample Type R Record the type of data collected on the plot using one of the following codes:

OCMA = Ocular Macroplot; FLLI = Flora Line Intercept 

FLCO = Flora Cover/Frequency; FLPO = Flora Point Cover

FLTR = Flora Tree Data

Species List Type R Record the completeness of the plant species list for the plot using the following codes:

C = Complete—All plant species present at time of sampling are recorded.

R = Reduced—Not all plant species are recorded. The list may be limited by a cover threshold (e.g., > 5% 

cover) or relative abundance (e.g., five most abundant species).

S = Selected—Not all plant species recorded. A protocol- or project-specific list of species are recorded when

ever they are present on a plot.

L = Lifeform Only—No species are recorded. Cover is only recorded for life forms, and usually by layer or 

size class within life form.

A complete species list is required for developing and describing new associations and alliances. See section 

2.43 of the technical guide for more information.

Plot Area R Record the area of the macroplot or belt transect in either acres or square meters, and the unit of measure (UOM) 

used. See section 2.41 of the technical guide for guidelines for determining plot size.

Area UOM R Record the unit of measure for the plot area, either acres or square meters.

Plot Size R Record actual plot dimensions. Radius for circular plots; width and length for rectangular plots. Also 

record the UOM used.

Size UOM R Record the unit of measure for the plot dimensions, either feet or meters.

Height UOM R Record the unit of measure for plant heights, either feet or meters.

Diameter UOM R Record the unit of measure for tree diameters.
Existing Vegetation Classification & Mapping Technical Guide 2A-9

2A.2.2 Canopy Cover by Life Form

Record the canopy cover for each item in this part of the form. Canopy cover is “the

percentage of ground covered by a vertical projection of the outermost perimeter of the

natural spread of foliage of plants. Small openings within the canopy are included”

(SRM 1989, USDA NRCS 1997). See technical guide sections 2.233 and 2.45 for more

information about canopy cover and ocular estimation techniques.

Complete the fields in this part of the form as described below.

All Veg Total Vegetation Cover. Record the percentage of the ground covered by a vertical projection of the outermost perimeter of the natural spread of foliage of all vascular plants

within the sample unit (plot or transect).

Trees Tree Cover. Record the total cover of trees—woody plants that generally have a single

main stem, have more or less definite crowns, and are usually equal to or greater than 5

meters in height at maturity (see technical guide section 2.421).

Shrubs Shrub Cover. Record the total cover of shrubs—woody plants that generally have several

erect, spreading, or prostrate stems which give it a bushy appearance, and are usually less

than 5 meters in height at maturity (see technical guide section 2.421). Shrub cover

includes the cover of dwarf shrubs.

Dwarf Shrubs Dwarf Shrub Cover. Record the total cover of dwarf shrubs—caespitose, suffrutescent,

matted, or cushion-forming shrubs which are typically less than 50 cm tall at maturity 

due to genetic and/or environmental constraints (see technical guide section 2.421).

Herbs Herb cover. Record the total cover of herbs—vascular plants without significant woody

tissue above the ground, with perennating buds borne at or below the ground surface 

(see technical guide section 2.421). Includes forbs, graminoids, ferns, and fern allies.

Herb cover must be equal to or less than the sum of graminoid cover and forb cover.

Graminoids Graminoid Cover. Record the total cover of graminoids—flowering herbs with relatively

long narrow leaves and inconspicuous flowers with parts reduced to bracts. Includes

grasses, sedges, rushes, and arrowgrasses (see technical guide section 2.421).

Forbs Forb Cover: Record the total cover of forbs—spore-bearing herbs or flowering herbs 

with relatively broad leaves and/or showy flowers (see technical guide section 2.421).

Include ferns or fern allies.

Dwarf shrubs are a subcategory of shrubs. Forbs, graminoids, and fern-likes are subcategories of herbs. Total canopy cover of additional life forms can be recorded in part 3 of

the Vegetation Composition Form as needed.

2A.2.3 Canopy Cover by Species

The third part of the Vegetation Composition Form is used to record data about vegetation

layers and individual plant species. This portion of the form is divided into two sections:

one for trees and shrubs and another for herbs and nonvascular organisms. 
2A-10 Existing Vegetation Classification & Mapping Technical Guide

Record a complete list of all plant species within the sampling unit. Record only

those species present in the plot. Do not record species that are present in the stand but

do not occur within the plot. Record the canopy cover for each species. Do not use cover

classes. Estimate percent canopy cover of each species, life form, layer, or size class

within the plot as follows: 

• Use 0.1 as “trace” for items present but clearly less than 1 percent cover.

• Estimate to the nearest 1 percent between 1 and 10 percent cover.

• Estimate to at least the nearest 5 percent between 10 percent and 30 percent cover.

• Estimate to at least the nearest 10 percent for values exceeding 30 percent cover.

Record a life form and life form modifier for each species using the codes in tables 2.5

and 2.6 of the technical guide, respectively (see technical guide section 2.49). These are

used for crosswalking to the FGDC physiognomic hierarchy and describing physiognomy

of associations and alliances (Jennings et al. 2004).

2A.2.4 Canopy Cover and Structural Data by Layer

Species data may also be recorded by layer if desired. The following instructions describe

how to record data for tree and shrub layers, and for tree and shrub species by layer.

2A.2.4.1 Tree Layer Definitions

Trees vary widely in mature height, from 5 meters to over 50 meters (FGDC 1997). This

variation must be taken into account when defining layers or height classes for trees. For

this purpose, a dwarf tree is defined as a tree that is typically less than 12 meters tall at

maturity due to genetic and/or environmental constraints. A stand of dwarf trees typically

has a site-specific potential height growth of less than 12 meters. The layers described

below are defined separately for dwarf trees where necessary. 

The following tree layers must be described whenever they are present in the sampling

unit (e.g., macroplot or transect):

• Overstory—The overstory layer includes all trees greater than or equal to 5 meters

in height that make up the forest canopy. In dwarf tree stands, the overstory consists

of trees that have attained at least half of their site-specific potential height growth

and make up the forest canopy.

• Regeneration—The regeneration layer includes all trees less than 5 meters in height.

In dwarf tree stands the regeneration layer includes trees that have attained less than

half of their site-specific potential height growth and are clearly overtopped by the

overstory trees.
Existing Vegetation Classification & Mapping Technical Guide 2A-11

The overstory may optionally be subdivided into the following sublayers, if they

occur, to describe stand structure in more detail:

• Main Canopy—The dominant and codominant overstory trees that receive direct

sunlight from above and make up the majority of the forest canopy.

• Supercanopy—Scattered overstory trees that clearly rise above the main canopy.

• Subcanopy—Overstory trees that are clearly overtopped by and separate from the

main canopy, but are larger and taller than the regeneration layer.

The regeneration layer may optionally be subdivided into the following sublayers:

• Saplings—Regenerating trees greater than 1.4 meters (4.5 feet) in height or regenerating dwarf trees greater than 1 meter in height.

• Seedlings—Regenerating trees less than 1.4 meters (4.5 feet) in height or regenerating

dwarf trees less than 1 meter in height.

2A.2.4.2 Tree Layer Data Requirements and Instructions

Canopy cover, predominant plant height, and predominant crown height must be recorded

for the tree overstory and regeneration layers. Predominant diameter must also be

recorded for the overstory. Record these attributes using the following procedures:

• Canopy Cover—Record percent canopy cover for each layer and optional sublayer

occurring within the sampling unit. Canopy cover of a layer cannot be greater than the

sum of the canopy cover values of its sublayers. Layer cover, however, can be and

typically is less than the sum of the sublayer covers due to overlapping of the sublayers.

• Predominant Plant Height—Record the predominant, or prevailing, tree height for

the overstory and regeneration layers to the nearest meter and nearest foot, respectively.

To determine this height, select a representative tree for the layer and estimate its

height using a clinometer and measuring tape. The representative tree for the overstory

layer must be in the main canopy. The representative tree for the regeneration layer

must be from the sublayer (sapling or seedling) with the most canopy cover.

Predominant plant height may also be recorded for each optional sublayer.

• Predominant Crown Height—Record the predominant, or prevailing, crown

height for the overstory and regeneration layers to the nearest meter. Crown height

is the vertical distance from ground level to the lowest whorl with live branches in

at least three of four quadrants around the stem. To determine crown height, select a

representative tree for the layer and estimate its crown height using a clinometer and

measuring tape. The representative tree for the overstory layer must be in the main

canopy. The representative tree for the regeneration layer must be from the sublayer
2A-12 Existing Vegetation Classification & Mapping Technical Guide

(sapling or seedling) with the most canopy cover. Predominant crown height may

also be recorded for each optional sublayer.

• Predominant Diameter—Record the predominant, or prevailing, tree diameter for

the overstory layer to the nearest inch. Predominant diameter is the prevailing diameter

of the most abundant tree species in a layer or sublayer. To determine this diameter,

select a representative tree and measure it with a diameter tape, using procedures

described in Common Stand Exam Field Guide. The representative tree for the overstory layer must be in the main canopy. Measure the diameter at breast height (DBH)

whenever possible; otherwise, measure diameter at root crown (DRC), and record the

diameter in the appropriate column (DBH or DRC) of the Vegetation Composition

Form.

Table 2A.1 shows an example of the required and optional data for tree layers.

2A.2.4.3 Data for Shrub Layers

The following shrub layers may optionally be described when present in the sampling

unit (e.g., macroplot or transect):

• Tall Shrubs—Shrubs greater than 2 meters in height. (May occasionally include

shrubs over 5 meters tall but clearly multistemmed.)

• Medium Shrubs—Shrubs 0.5 to 2 meters in height.

• Low Shrubs—Shrubs less than 0.5 meter in height.

When shrub layers are described, canopy cover and predominant plant height should

be recorded for each layer. Predominant crown height may also be recorded. Record

these attributes using the following procedures:

• Canopy Cover—Record percent canopy cover for each shrub layer occurring within

the sampling unit. Total shrub cover cannot be greater than the sum of the individual

layer cover values, but may be less.

Life LF Canopy Pred. Plant Pred. Crown Pred. Pred.

Form Mod. Layer Species Cover Height (m) Height (m) DBH (in) DRC

T — TO — 45 10 6 12 —

T —TOSP — 5 12 8 15 —

T —TOMC — 40 10 6 12 —

T —TOSB — 10 7 2.5 8 —

T — TR — 10 4 0.3 t

T — TRSA — 5 4 0.3 t

T — TRSE — 5 0.3 0

Table 2A.1. Example of completed data for tree layers and sublayers.
• Predominant Plant Height—Record the predominant, or prevailing, height of each

shrub layer to at least the nearest foot. Predominant plant height is the prevailing

upper height of the shrubs within a layer. To determine this height, select a representative individual shrub andmeasure its height with an appropriate method (e.g.,

tape measure for low to medium shrubs or clinometer for tall shrubs).

• Predominant Crown Height—Record the predominant crown height for each shrub

layer to at least the nearest foot. Crown height for shrubs is the vertical distance

from ground level to the lowest live foliage or branches. To determine crown height,

select a representative shrub for the layer and measure or estimate its crown height.

Table 2A.2 shows an example of completed shrub layer data. 

2A.2.5 Optional Canopy Cover and Structural Data by Species by Layer

Canopy cover and structural data may optionally be recorded separately for each species

for each layer or sublayer in which it occurs.

2A.2.5.1 Data for Tree Species by Layer

Canopy Cover

Record the total canopy cover of each tree species and the canopy cover of each species

within each layer in which it occurs. Cover by sublayer may also be recorded. This may

require up to eight rows of data, depending on the number of sublayers in which a species

occurs. An example is shown in Table 2A.3 below with required data in bold text. In this

example, the canopy cover of Ponderosa pine (Pinus ponderosa) is 45 percent. Within

the overstory and regeneration layers its canopy cover is 35 and 10 percent, respectively,

indicating there is no overlap between the two layers. No sapling or seedling occurs

Life LF Canopy Pred. Plant Pred. Crown

Form Mod. Layer Species Cover Height (m) Height (m)

S — ST — 13 1

S — SM — 9 1 0.3

S — SL — Tr 0.3 0

T — TRSE — 5 0.3 0

Table 2A.2. Example of completed data for shrub layers.

Life LF Canopy

Form Mod. Layer Species Cover

T TN — PIPO 45

T TN TO PIPO 35

T TN TOMC PIPO 30

T TN TOSB PIPO 10

TR PIPO 10

T TN TRSA PIPO 6

T TN TRSE PIPO 4

Table 2A.3. Example of completed data for shrub layers.

Existing Vegetation Classification & Mapping Technical Guide 2A-13
2A-14 Existing Vegetation Classification & Mapping Technical Guide

directly under an overstory tree. However, there is overlap between main canopy and

subcanopy trees. Ponderosa pine cover is 30 percent in the main canopy and 10 percent in

the subcanopy, while overstory cover is only 35 percent. This indicates 5-percent overlap

between main canopy and subcanopy Ponderosa pine. 

The possibility of overlap between sublayers requires that overstory and regeneration

cover for each tree species is estimated or measured directly, not calculated by summing

the sublayer values. When recording species cover by sublayer using the ocular macroplot

method, it is most efficient to first estimate canopy cover by sublayer, and then estimate

the overlap (if any) between sublayers to derive canopy cover for the overstory and

regeneration layers.

Predominant Plant Height

Record predominant height of each tree species for each layer in which it occurs. To

determine this height, select a representative tree and estimate its height with a clinometer

and measuring tape, using procedures described in Common Stand Exam Field Guide.

Predominant Crown Height

Record predominant crown height of each tree species for each layer in which it occurs.

To determine this height, select a representative tree and estimate or measure the vertical

distance from the ground to the canopy base.

Predominant Age

Record the predominant age of each tree species in the overstory layer. Refer to the

Common Stand Exam Field Guide for methods of determining tree age.

Predominant Diameter

Record predominant diameter (DBH or DRC as appropriate) for the overstory layer. To

determine this diameter, select a representative tree and measure it with a diameter tape,

using procedures described in Common Stand Exam Field Guide.

Stem Count

Record stem counts for each tree species occurring in the regeneration layer. Stems may

optionally be recorded by sublayer (sapling and seedling). Counts can be made on the

entire plot or a portion of the plot depending on the density of each species. When stems

are counted on a portion of the plot, the fraction of the plot and the raw count are recorded

in the Remarks section of the form. These values are then used to calculate a count for the

entire plot, which is recorded in the stem count column of the form.

An example of a completed data set for one tree species in shown below in Table

2A.4. Predominant plant height, crown height, diameter, age, and stem count have been

added to the canopy cover data in Table 2A.1. 
Life LF Canopy Pred. Pred. Pred. Pred. Pred. Stem

Form Mod. Layer Species Cover Plant Ht Crown Ht DBH (in) DRC Age Count

T TN — PIPO 45

T TN TO PIPO 35 40 15 30 — 150

T TN TOMC PIPO 30 40 15 30 — 150

T TN TOSB PIPO 10 20 5 12 — 80

T TN TR PIPO 10 4 0.5 13

T TN TRSA PIPO 6 4 0.5 4

T TN TRSE PIPO 4 0.3 0 9

Table 2A.4. Example of completed data for tree layers and sublayers.

Life LF Canopy Pred. Plant Pred. Crown

Form Mod. Layer Species Cover Height (m) Height (m)

S SBD — QUGA 9 1 0.2

S SBD ST QUGA 1 3 1

S SBD SM QUGA 8 1 0.2

S SM — ARTRP4 1 0.7 0.2

S SM SM ARTRP4 1 0.7 0.2

Table 2A.5. Example of completed data for shrub species by layers.

2A.2.5.2 Data for Shrub Species by Layer

Canopy Cover

Record the total canopy cover of each shrub species. The canopy cover of each species

within each layer in which it occurs may optionally be recorded, but is not required.

This may require up to four rows of data, depending on the number of layers in which a

shrub species occurs. The possibility of overlap between layers requires that total

canopy cover for each shrub species be estimated or measured directly, not calculated by

summing the species by layer cover values.

Predominant Crown Height

Record predominant crown height of each shrub species for each layer in which it

occurs. To determine this height, select a representative shrub and estimate or measure

the vertical distance from the ground to the lowest live foliage.

Predominant Height

Record predominant height of each shrub species or optionally for each layer in which

the species occurs. Predominant height is the prevailing upper height of the shrub

species within a layer. To determine this height, select a representative individual shrub

and measure its height with an appropriate method (e.g., tape measure for low to medium shrubs or clinometer for tall shrubs).

Table 2A.5 shows an example of completed shrub species and species by layer data. 

Existing Vegetation Classification & Mapping Technical Guide 2A-15
2A-16 Existing Vegetation Classification & Mapping Technical Guide

2A.2.6 Basal Area Data

Basal area may optionally be collected using a single prism point at the center of a

macroplot or midpoint of a transect. Follow the procedures in the Common Stand Exam

Field Guide. Record the basal area, in square feet per acre, and the expansion factor

(BAF) of the prism used.

2A.2.7 Blank Vegetation Composition Form and Completed Examples

A blank Vegetation Composition Form is provided on the following page. It is followed

by examples of a completed General Site Data Form and Vegetation Composition Form.
Existing Vegetation Classification & Mapping Technical Guide 2A-17

Vegetation Composition Form
2A-18 Existing Vegetation Classification & Mapping Technical Guide

General Site Data Form

USDA Forest Service
Existing Vegetation Classification & Mapping Technical Guide 2A-19

Vegetation Composition Form
Existing Vegetation Classification & Mapping Technical Guide 3A-1

Appendix 3A. 

Example of Mapping Keys to Life Form and 

Dominance Types

This appendix was taken from USDA Forest Service, Pacific Southwest Region, Forest

Inventory and Analysis User’s Guide, May 2002, Chapter 700—Appendices, CALVEG Types.

Example Mapping Keys To Life Form and Dominance

Types in the Pacific Southwest Region

Field Key to CALVEG Dominance Types in Zone 1 – North Coast 

and Montane

CALVEG Key for North Coast and Montane Ecological Province

(CALVEG Zone 1) Used in Type Identification, Mapping, and

Accuracy Assessment of Map Products

I. Key to Lifeforms

1A. If total vegetation plot cover > 10% in conifers ... 2

1B. If total vegetation plot cover < 10% in conifers ... 3

2A. If total vegetation plot cover > 15% in hardwoods ... mixed lifeform and go to II

Key to Conifers for the conifer component and III Key to Hardwoods for the hardwood

component. 

2B. If total vegetation plot cover < 15% in hardwoods conifer lifeform and go to II

Key to Conifers 

3A If total vegetation plot cover >10% in hardwoods hardwood lifeform and go to III

Key to Hardwoods

3B. If total vegetation plot cover <10% in hardwoods ... 4

4A. If total vegetation plot cover > 10% in shrubs ... shrub lifeform and go to IV Key

to Chaparrals, Shrubs and Subshrubs

4B. If total vegetation plot cover < 10% in shrubs ... 5

5A. If total vegetation plot cover > 10% in other vegetation ... herbaceous lifeform and

go to V Key to Grasses and Forbs

5B. If total plot cover < 10% in other vegetation ... non-vegetated and go to VI Key to

Non-Vegetated Types
3A-2 Existing Vegetation Classification & Mapping Technical Guide

II. Key to Conifers

cc = conifer canopy cover

1A. A single species of conifer species has > 50% cc ... 2

1B. No single conifer species has > 50% cc ... 40

2A. One Cypress species has > 50% cc ... 3

2B. Another single conifer species has > 50% cc ...8

3A. Sargent Cypress has > 50% cc ... MS (Sargent Cypress)

3B. Not as above ... 4

4A. McNab Cypress has > 50% cc ... MN (McNab Cypress)

4B. Not as above ... 5

5A. Pygmy Cpress has > 50% cc ... MY (Pygmy Cypress)

5B. Not as above ... 6

6A. Baker Cypress has > 50% cc ... MO (Baker Cypress)

6B. Not as above ... 7

7A. Monterey Cypress has > 50% cc ... MM (Monterey Cypress)

7B. Not as above ... 47

8A. Coastal Redwood has > 50% cc ... RW (Redwood)

8B. Not as above ... 9

9A. Port Orford Cedar has > 50% cc ... PO (Port Orford Cedar)

9B. Not as above ... 10

10A. Red Fir has > 50% cc and White Fir present, the combination > 75% cc ... 

RF (Red Fir)

10B. Not as above ... 11

11A. White Fir has > 50% cc and Red Fir present, the combination > 75% cc ... 

WF (White Fir)

11B. Not as above ... 12
Existing Vegetation Classification & Mapping Technical Guide 3A-3

12A. Ponderosa Pine has > 75% cc (or Ponderosa Pine and Jeffrey Pine in combination

has > 75% and Ponderosa Pine > Jeffrey Pine) and Great Basin species (Bitterbrush,

Curlleaf Mountain Mahogany, Basin Sagebrush, Western Juniper, or California

Juniper) do not occur in understory ... PP (Ponderosa Pine)

12B. Not as above ... 13

13A. Ponderosa Pine has > 75% cc (or Ponderosa Pine and Jeffrey Pine in combination

has > 75% cc ) and Great Basin species (Bitterbrush, Curlleaf Mountain Mahogany,

Basin Sagebrush, Western Juniper, or California Juniper) occur in understory ... EP

(Eastside Pine)

13B. Not as above ... 14

14A. Jeffrey Pine has > 75% cc (or Ponderosa Pine and Jeffrey Pine in combination

has > 75% and Jeffrey Pine > Ponderosa Pine) and Great Basin species (Bitterbrush,

Curlleaf Mountain Mahogany, Basin Sagebrush, Western Juniper, or California

Juniper) do not occur in understory ... JP (Jeffrey Pine)

14B. Not as above ... 15

15A. Jeffrey Pine has > 75% cc and Great Basin species (Bitterbrush, Curlleaf

Mountain Mahogany, Basin Sagebrush, Western Juniper, or California Juniper)

occur in understory ... EP (Eastside Pine)

15B. Not as above ... 16

16A. Pacific Douglas-Fir has > 75% cc ... DF (Pacific Douglas-Fir)

16B. Not as above ... 17

17A. Whitebark Pine has > 75% cc ... WB (Whitebark Pine)

17B. Not as above ... 18

18A. Western White Pine has > 75% cc ... WW (Western White Pine)

18B. Not as above ... 19

19A. Foxtail Pine has > 75% cc ... FP (Foxtail Pine)

19B. Not as above ... 20

20A. Mountain Hemlock has > 75% cc ... MH (Mountain Hemlock)

20B. Not as above ... 21
3A-4 Existing Vegetation Classification & Mapping Technical Guide

21A. Knobcone Pine has > 75% cc ... KP (Knobcone Pine)

21B. Not as above ... 22

22A. Western Juniper has > 75% cc ... WJ (Western Juniper)

22B. Not as above ... 23

23A. Gray Pine has > 75% ... PD (Gray Pine)

23B. Not as above ... 24

24A. Lodgepole Pine has > 75% cc ... LP (Lodgepole Pine)

24B. Not as above ... 25

25A. Engelmann Spruce has > 75% cc ... EA (Engelmann Spruce)

25B. Not as above ... 26

26A. Brewer Spruce has > 75% cc ... PB (Brewer Spruce)

26B. Not as above ... 27

27A. Grand Fir has > 75% cc ...GF (Grand Fir)

27B. Not as above ... 28

28A. Bishop Pine has > 75% cc ... PM (Bishop Pine)

28B. Not as above ... 29

29A. Monterey Pine has > 75% cc ... PR (Monterey Pine)

29B. Not as above ... 30

30A. Beach Pine has > 75% cc ... PS (Beach Pine)

30B. Not as above ... 31

31A. Sitka Spruce has > 75% cc ... SK (Sitka Spruce)

31B. Not as above ... 32

REM: This starts the > 50 and < 75% two-conifer species groups

32A. Douglas-Fir has > 50% cc; Redwood is present ... RD (Redwood - Douglas-Fir)

32B. Not as above ... 33
Existing Vegetation Classification & Mapping Technical Guide 3A-5

33A. Douglas-Fir has > 50% cc; Ponderosa Pine has > 20% cc ... DP (Douglas-Fir -

Ponderosa Pine)

33B. Not as above ... 34

34A. Douglas-Fir has > 50% cc; White Fir has > 20% cc ... DW (Douglas-Fir - White

Fir)

34B. Not as above ... 35

35A. Douglas-Fir has > 50% cc; Grand Fir has > 20% cc ... DG (Douglas-fir -

Grand Fir)

35B. Not as above ... 36

37A. Ponderosa Pine has > 50% cc; White Fir has > 20% cc ... PW (Ponderosa Pine

- White Fir)

37B. Not as above ... 38

38A. Sitka Spruce has > 50% cc; Redwood has > 20% cc ... SR (Sitka Spruce -

Redwood)

38B. Not as above ... 39

39A. Sitka Spruce has > 50% cc; Grand Fir has > 20% cc ... SG Sitka Spruce -

Grand Fir)

39B. Not as above ... 40

REM: this starts condition in which no single conifer species > 50% sc

40A. Red Fir in combination with White Fir > 75% cc and Red Fir > White Fir ... RF

(Red Fir)

40B. Not as above ... 41

41A. White Fir in combination with Red Fir > 75% cc and White Fir > Red Fir ...

WF (White Fir)

41B. Not as above ... 42

42A. Any of these species in combination are present but do not dominate the cc:

Mountain Hemlock, Foxtail Pine, Western White Pine, Whitebark Pine ... SA

(Subalpine Conifers)

42B. Not as above ... 43
3A-6 Existing Vegetation Classification & Mapping Technical Guide

43A. Any of these species in combination are present but do not dominate the cc: Noble

Fir, Alaska Cedar, Engelmann Spruce, Brewer Spruce, Port Orford Cedar, Pacific

Yew ... MK (Klamath Mixed Conifer)

43B. Not as above ... 44

44A. Ponderosa Pine and/or Sugar Pine in combination > 10% cc ... MP (Mixed

Conifer - Pine) 

44B. Not as above ... 45

45A. White Fir and Red Fir combined have > 20% cc ... MF (Mixed Conifer - Fir)

45B. Not as above .. 46

46A. Any of these species in combination are present but do not dominate the cc:

Jeffrey Pine, Lodgepole pine, McNab Cypress, Sargent Cypress, Gray Pine, or

Western White Pine and elevation is less than 5000 ft (1525 m) ... MU (Ultramafic

Mixed Conifer)

46B. Not as above ... 47

47. Conifer type not determined ... UC

III. Key to Hardwoods

hc = hardwood canopy cover

1A. One hardwood species (or genus) has > 50% hc ... 2

1B. No single hardwood species (or genus) has > 50% hc ... 23

2A. Tanoak has > 50% hc ... QT (Tanoak [Madrone])

2B. Otherwise ... 3

3A. Madrone has > 50% hc ... QH (Madrone)

3B. Otherwise ... 4

4A. Willow has > 50% hc ... QO (Willow)

4B. Otherwise ... 5

5A. Red Alder has > 50% hc ... QR (Red Alder)

5B. Otherwise ... 6
Existing Vegetation Classification & Mapping Technical Guide 3A-7

6A. White Alder has > 50% hc ... QE (White Alder)

6B. Otherwise ... 7

7A. Mountain Alder has > 50% hc ... TA (Mountain Alder)

7B. Otherwise ... 8

8A. Black Cottonwood has > 50% hc ... QX (Black Cottonwood)

8B. Otherwise ... 9

9A. Fremont Cottonwood has > 50% hc ... QF (Fremont Cottonwood)

9B. Otherwise ... 10

10A. Quaking Aspen has > 50% hc ... QQ (Aspen)

10B. Otherwise ... 11

11A. Bigleaf Maple has > 50% hc ... QM (Bigleaf Maple)

11B. Otherwise ... 12

12A. Tree Chinquapin has > 50% hc ... TC (Tree Chinquapin)

12B. Not as above ... 13

13A. Black Oak has > 50% hc ... QK (Black Oak)

13B. Not as above ... 14

14A. Oregon White Oak has > 50% hc ... QG (Oregon White Oak)

14B. Not as above ... 15

15A. Blue Oak has the greatest hardwood cover ... QD (Blue Oak)

15B. Not as above ... 16

16A. Coast Live Oak has > 50% hc ... QA (Coast Live Oak)

16B. Not as above ... 17

17A. Canyon Live Oak has > 50% hc ... QC (Canyon Live Oak)

17B. Not as above ... 18

18A. Interior Live Oak has > 50% hc ... QW (Interior Live Oak)

18B. Not as above ... 19
3A-8 Existing Vegetation Classification & Mapping Technical Guide

19A. Valley Oak has > 50% hc ... QL (Valley Oak)

19B. Not as above ... 20

20A. California Bay has > 50% hc ... QB (California Bay)

20B. Not as above ... 21

21A. Eucalyptus of any species has > 50% hc ... QZ (Eucalyptus)

21B. Not as above ... 22

22A. California Buckeye has > 50% hc ... QI (California Buckeye)

22B. Not as above ... Unknown Hardwood Type ... HD

REM: this begins the mixed hardwoods groups; no single species > 50% hc

23A. Combination of Tanoak and Madrone has > 50% hc ... QT (Tanoak [Madrone])

23B. Otherwise ... 24 

24A. Black or Fremont Cottonwood and any species of Alder (Red, White, Sitka, or

Mountain) in combination have > 50% hc ... QJ (Cottonwood - Alder)

24B. Otherwise ... 25

25A. Willow of any species and Aspen in combination have > 50% hc ... QS (Willow -

Aspen)

25B. Otherwise ... 26

26A. Willow of any species and Alder (Red, White, Sitka, or Mountain) in combination have > 50% hc ... QY (Willow - Alder)

26B. Otherwise ... 27

27A. Otherwise a mixture of hardwoods, including Valley Oak, California Bay,

Canyon, Coast and Interior Live Oaks, California Black and Oregon White Oak,

Blue Oak, Madrone, and California Buckeye ... NX (Mixed Hardwoods)

27B. Otherwise ... Unknown Hardwood Type ... HD

IV. Key to Shrubs

sc = shrub canopy cover

1A. Pygmy (Ft. Bragg) Manzanita has > 10% sc ... AN (Pygmy [Ft. Bragg]

Manzanita)

1B. Not as above ... 2
Existing Vegetation Classification & Mapping Technical Guide 3A-9

2A. Either Salal or California Huckleberry have > 50% sc ... CB (Salal - California

Huckleberry)

2B. Not as above ... 3

3A. Curlleaf Mountain Mahogany has > 50% sc ... BM (Curlleaf Mountain

Mahogany)

3B. Otherwise ... 4

4A. Basin Sagebrush as > 50% sc ... BS (Basin Sagebrush)

4B. Not as above ... 5

5A. Bitterbrush has > 50% sc ... BB (Bitterbrush)

5B. Not as above ... 6

6A. Low Sagebrush as > 50% sc ... BL (Low Sagebrush)

6B. Not as above ... 7

7A. Any species of Rabbitbrush alone or in combination has > 50% sc ... BR

(Rabbitbrush)

7B. Not as above ... 8

7A. Chamise has > 50% sc ... CA (Chamise)

7B. Not as above ... 8

8A. Whiteleaf Manzanita has > 75% sc ... CW (Whiteleaf Manzanita)

8B. Not as above ... 9

9A. Greenleaf Manzanita has > 75% sc ... CG (Greenleaf Manzanita)

9B. Not as above ... 10

10A. Pinemat Manzanita has > 75% sc ... CN (Pinemat Manzanita)

10B. Not as above ... 11

11A. Manzanita of any other species alone or in combination with or without

Whiteleaf or Greenleaf Manzanita > 75% sc ... SD (Manzanita)

11B. Not as above ... 12

12A. Huckleberry Oak has > 75% sc ... CH (Huckleberry Oak)

12B. Not as above ... 13
3A-10 Existing Vegetation Classification & Mapping Technical Guide

13A. Brewer Oak has > 75% sc ... CJ (Brewer Oak)

13B. Not as above ... 14

14A. Wedgeleaf Ceanothus has > 75% sc ... CL (Wedgeleaf Ceanothus)

14B. Not as above ... 15

15A. Blueblossom Ceanothus has > 75% sc ... SC (Blueblossom Ceanothus)

15B. Not as above ... 16

16A. Snowbrush has > 75% sc ... CV (Snowbrush)

16B. Not as above ... 17

17A. Coyote Brush has > 75% sc ... CK (Coyote Brush)

17B. Not as above ... 18

REM: mixed species:

18A. Any other combination of Ceanothus, including non-dominant Wedgeleaf,

Deerbrush, Blueblossom, or Snowbrush has > 75% sc ... CC (Ceanothus Chaparral)

18B. Not as above ... 19

19A. Salal and California Huckleberry in combination has > 75% sc ... CB (Salal -

California Huckleberry)

19B. Not as above ... 20

20A. Any other species of scrubby oaks alone or in combination of the following have >

75% sc: Scrub Oak, Shrub Interior Live Oak, Shrub Canyon Live Oak, Leather

Oak, Sadler Oak, Huckleberry Oak, Oregon White or Brewer Oak, California

Black Oak ... CS (Scrub Oak)

20B. Not as above ... 21

21A. Any of following species present and in combination have > 10% sc: Blueblossom

Ceanothus, Coastal Whitethorn, Hairy Manzanita, Shrub California Bay, Salal,

California Huckleberry, Wax Myrtle, Yellow Bush Lupine, any species of

Rhododendron, Red Huckleberry, Thimbleberry ... NC (North Coastal Scrub)

21B. Not as above ... 22

22A. Any of the following in combination have > 10% sc: Chamise, Wedgeleaf

Ceanothus, Lemmon Ceanothus, Whiteleaf Manzanita, Common Manzanita,
Existing Vegetation Classification & Mapping Technical Guide 3A-11

Stanford Manzanita, Birchleaf Mountain Mahogany, Toyon, Pine Mat Ceanothus,

Hollyleaf Redberry ... CQ (Lower Montane Mixed Chaparral)

22B. Not as above ... 23

23A. Any of the following in combination of two or more have > 10% sc: Greenleaf

Manzanita, Hoary Manzanita, Mountain Whitethorn, Deerbrush, Cascara, Shrub

Canyon Live Oak, Bush Chinquapin, Fremont Silktassel, any species of Snowberry,

Mahala Mat ... CX (Upper Montane Mixed Chaparral)

23B. Not as above ... 24

24A. Elevation < 5000 ft (1525 m); any of the following in combination have > 10% sc:

Jepson Ceanothus, ShrubTanoak, Creeping Barberry, Dwarf Barberry, Piper’s

Oregongrape, Wavyleaf Ceanothus, Huckleberry Oak, Whiteleaf Manzanita,

Interior Silktassel, Siskiyou Mat, Leather Oak ... C1 (Ultramafic Mixed

Chaparral)

24B. Not as above ... 25

25A. Elevation > 5000 ft (1525 m); any of following alone or in combination have >

10% sc: Bush Chinquapin, Shrub Tanoak, Mountain Whitethorn, Pinemat

Manzanita, Huckleberry Oak, Bitter Cherry ... CM (Upper Montane Mixed

Shrub)

25B. Not as above. .. 26

26. Unknown Shrub Type ... US

V. Key to Herbaceous

hg = herbaceous/grass canopy cover

1A. Annual grasses mixed with annual and/or perennial forbs have > 50% hg ... HG

(Annual Grass - Forb)

1B. Not as above ... 2

2A. Hydrophytic grasses and grass-like species (sedges, rushes, bulrushes) in mixture

with hydrophytic herbaceous species (false hellebore, lily, shooting star, gentian, etc.)

growing mainly in organic soil have > 50% hg ...HJ (Wet Meadows)

2B. Not as above ... 3
3A-12 Existing Vegetation Classification & Mapping Technical Guide

3A. Pastures or semi-natural areas containing mixtures of annual and perennial grasses

and annual and/or perennial forbs have > 50% hg ... HM (Perennial Grass - Forb)

3B. Not as above ... 4

4A. Coastal brackish or salt marshes surrounding open water containing mixtures of

Common Pickleweed, Cordgrasses, or Saltgrass > 50% hg ... HC (Pickleweed -

Cordgrass) 

4B. Not as above ... 5

5A. Marshes adjacent to perennial fresh water sources containing mixtures of Tule or

other Bulrushes and Cattails rooting below the water’s surface have > 50% hg ... HT

(Tule - Cattail)

5B. Unknown herbaceous or grassland type ... Grass-GR

VI. Key to Non-Vegetated

nvc = non-vegetated cover

1A. Agricultural uses comprise > 50% nvc ... AG (Agriculture)

1B. Not as above ... 2

2A. Coastal dunes comprise > 50% nvc ... DU (Dunes)

2B. Not as above ... 3

3A. Snow or ice fields at the highest elevations comprise > 50% nvc ... SN (Snow/Ice)

3B. Not as above ... 4

4A. Urban or otherwise developed landscapes (highways, etc.) > 50% nvc ... UB

(Urban or Developed)

4B. Not as above ... 5

5A. Open water or confined water courses occupy > 50% nvc ... WA (Water)

5B. Not as above ... 6

6A. Otherwise naturally barren landscapes (cliffs, bedrock, etc.) occupy > 50% nvc ...

BA (Barren)

6B. Unknown type ... NF (Non-Forested)
Existing Vegetation Classification & Mapping Technical Guide 3B-1

Appendix 3B. 

Example of a Structured Aerial Photointerpretation Data

Gathering Protocol

This appendix was taken from the Northern Region Vegetation Mapping Project Aerial

Photointerpretation Guides, USDA Forest Service, Missoula, MT and contains schematic

guides for collecting and documenting data using aerial photointerpretation methods. 

Training and accuracy assessment data are generated through a structured aerial

photointerpretation process that integrates a variety of field sampled inventory datasets.

Our experience suggests that an aerial perspective is often useful for remote sensing

training data acquisition, and that skilled interpreters can add local knowledge and

experience to the classification process. Additionally, resource aerial photography remains

the most available remote sensing data source; however, we integrate high-resolution,

multispectral data with resource photography where available. This structured photo

interpretation process provides an explicit mechanism to integrate existing field sample

data from a variety of sources, both within the U.S. Department of Agriculture (USDA)

Forest Service and from cooperating entities. Existing field data is screened to ensure

data quality and currency using a standardized process. This provides the opportunity to

benefit from the agency’s substantial investment in field data while screening out data

rendered unusable by management activities, disturbance agents, and/or time since collection. Through this process the image interpreter is able to “fit” field data and other

ancillary data to the segmented imagery. This process accomplishes the same objective

described by Robinson and Tilton (1991), but fits the training data to the segmentation

rather than fitting the segmentation to the training data. Common image interpretation

techniques are used to characterize elements of vegetation pattern that comprise life

form, dominance type, tree size class, and tree canopy cover (Avery 1977, Campbell

1987, Lillisand and Kiefer 1987, Lachowski et al. 1995). The variables collected include

life form/land use class cover percent and connectivity, dominance type cover percent

and connectivity, tree size class cover percent, tree canopy cover percent and connectivity,

and total vegetation canopy cover percent. 
3B-2 Existing Vegetation Classification & Mapping Technical Guide

Northern Region Vegetation Mapping Project

Photointerpretation Guide

Model Number/Forest Number Coverage Name. Column Name: MNFN 4 digits

Photointerpreter. Column Name: PI 3 characters

Record photo interpreter’s Initials (2 or 3 characters). 

Polygon_link. Column Name: Poly_link 6 digits 

Record Polygon_link from the Model/Image Analyst Polygon Coverage. 

Flag. Column Name: Flag 1 digit

• 0 = No flag.

• 1 = Flag—Discrepancy between photo and Thematic Mapping (TM) imagery. 

- For example, green, live trees on photo and recent burned or harvest on TM imagery.

- Make note of condition in General Comments.

- If a poly-link is flagged, it is not photointerpreted and therefore RPN is not needed.

• 2 = Flag—Discrepancy likely between photo and TM imagery due to anticipated insect and 

pathogen related mortality. 

• 3–7= Reserved flags. 

• 8–9= Image analyst flags that can be used at their discretion.

Reference Data Region-Polygon Number. Column Name: RPN 4 digits

Consecutive number (1–9,999) assigned by image analyst to those region-polygons selected for 

photointerpretation.

Owner. Column Name: Own 2 digits 

Attributed by GIS routine. Record 2-digit traditional National Forest identifier or R1-VMP code for

“Other Ownership.” 

District. Column Name: Dist 2 digits. 

Attributed by GIS routine. Record 2-digit Ranger District identifier for National Forest lands.

Aerial Photo Identification. Column Name: API 17 characters 

Record the photo that covers the majority of the region’s polygon, leaving no spaces in code.

• First 6 digits represent Photo Symbol/Project ID. 

• Next 4 digits represent the roll number. 

• Next 4 digits represent the exposure number.

• Last 4 digits represent the flight line number; use at the discretion of the image analyst. 

Photo Scale: Column Name: PS 2 characters

Record the nominal photo scale using the following convention:

• 1:16,000—code as 16.

• 1:5,000—code as 5. 

DOQQ Quadrangle: Column Name: Quad 20 characters

Optional—note name of quad. 
Existing Vegetation Classification & Mapping Technical Guide 3B-3

Manual Classification Code. Column Name: MCC 3 characters

Interpretation of TM data only where region consists of nearly 100% of the following classes:

Use this field and the codes below to identify poly_links that can be used to assist in manual classification of nonforested types. If these codes are used, stop data entry after this field.

CLD Cloud 

SCD Shadow—cloud

STP Shadow—topographic

RCK Rock Includes scree

BAR Bare ground Includes gravel pits, sandbars

WAT Water

SNW Snow and ice

RDT Recently dead trees With foliage attached—red, orange, yellow

BRN Recently burned

RDS Gravel and native surface roads

PAV Paved roads Concrete or blacktop highways 

MAN Man-made structures Buildings 

Inventory Data Type. Inventory Data Identifier. (Also known 

Column Name: IDT 2 characters as Setting Identifier)

Column Name: IDI XX characters

Record the type of data used to assist in the 

photointerpretation. If multiple data types are 

available, code the one judged to be the best. 

0 No Data 

1 R1 Standard Exam or Quick Plot

2 R1 PGP

3 R1 Other

4 R1VMP-CSE field data

5 ECODATA plant comp data

6 ECODATA tree data

7 FIA

8 IPNF CVS

9 IPSAC training data—ground and helicopter

10 Image analyst walk-through, drive-by

50 Flathead Indian Reservation

51 Nez Perce Indian Reservation

61 GNP Vegetation Mapping Project

62 BLM

63 FWS

64 Other Federal

71 Montana State

72 Idaho State

Record the stand or plot number associated with

the reference data as follows:

• 0 No Data

• FSVeg 14 characters

• ECODATA XX characters 

• FIA data XX characters 

• IPSAC data XX characters 

• IPNF CVS data XX characters 

• GNP VMP data XX characters 

• Other measured data XX characters 

Walk-through, drive-by image analyst’s last name.
3B-4 Existing Vegetation Classification & Mapping Technical Guide

Life Form Data

Life Form. Column Name: LF 3 characters. Identify the life form.

A. Tree life form > 10% canopy cover ............................TRE.

A. Tree life form < 10% canopy cover....................................Go to B.

B. Shrub life form > 10% canopy cover ..........................SHR.

B. Shrub life form < 10% canopy cover..................................Go to C.

C. Grass/Forb life form > 10% canopy cover ................... GFB.

C. Grass/Forb life form < 10% canopy cover...........................Go to D.

D. TRE+SHR+GFB+ nonvascular > 10% canopy cover ......NDL [no dominant life form].

D. TRE+SHR+GFB+ nonvascular < 10%..............................Go to E.

E. TRE+SHR+GFB+ nonvascular < 10% and > 1% canopy cover...SVG [sparsely vegetated].

E. TRE+SHR+GFB+ nonvascular < 1%.................................NVG [nonvegetated].

Life Form Code. Column Name: LFC. 1 character. Optional Use.

This field can be hidden during data entry, populated with an update query at a later date, then 

converted to a .dbf and joined to region-polygon coverage for use with eCognition.

1 TRE—Tree

2 SHR—Shrub

3 GFB—Grass/forb

4 NDL—No dominant life form

5 SVG—Sparsely vegetated

6 NVG—Nonvegetated

Life Form Connectivity. Column Name: LFCon 2 characters

Identify the connectivity of the life forms above.

DA: Disaggregated SA: Semiaggregated AL: Aggregated-Linear AN: Aggregated-Nonlinear

Example: Example: Example: Example:

Each “patch” < 1% cover. “Small” contiguous patches of Contiguous linear features of “Larger” contiguous patch of

similar life forms. dissimilar life forms. of dissimlar life form. dissimilar life forms.

roads, powerlines, riparian 

features, avalanche chutes, 

ski runs.
Existing Vegetation Classification & Mapping Technical Guide 3B-5

Tree Size Class Canopy Cover. Column Names: See Below 2 digits

Estimate canopy cover for each of the five classes below; zero-fill any classes without trees.

• Estimate canopy cover to the nearest 1% for size classes that are < 10%. 

• You may estimate canopy cover to the nearest 5% for size classes with canopy cover > 10%.

• Ensure that the total of all size classes represents the total canopy coverage for the polygon.

• Ensure that for polygons identified as tree life form, the total of all size classes > 10%, and that

for polygons not identified as tree life form, the total of all size classes < 10%.

TLFC Tree life form canopy cover All sizes

VLCC Very large tree canopy cover > 20.0-in d.b.h.

LTCC Large tree canopy cover 15.0–19.9-in d.b.h.

MTCC Medium tree canopy cover 10.0–14.9-in d.b.h.

STCC Small tree canopy cover 5.0–9.9-in d.b.h.

SSCC Seedlings/saplings canopy cover < 5.0-in d.b.h.

Tree Dominance Type 1. Column Name: Dom_1 14 characters

Based on photointerpretation of canopy cover. Use common four-letter abbreviations for species, such as

PIPO, PICO, and ABLA for single-, two- and three-species mixes.

A. Single most abundant species > 60% of total canopy cover......... List single species.

A. Single most abundant species < 60% of total canopy cover........ Go to B.

B. 2 most abundant species > 80% of total canopy cover and

each species individually is > 20% of total canopy cover ..List 2 species, in order of abundance.

B. 2 most abundant species < 80% of total canopy cover................. Go to C.

C. 3 most abundant species > 80% of total canopy cover and each species individually is > 20% of 

total canopy cover..................List 3 species, in order of abundance.

C. 3 most abundant species < 80% of total canopy cover.................... Go to D.

D. Shade intolerant species total CC > shade tolerant species total CC.....IMXS.

D. Shade intolerant species total CC < shade tolerant species total CC.....Go to E.

E. GF+C+WH canopy cover > AF+S+MH canopy cover ..........................TGCH.

E. GF+C+WH canopy cover < AF+S+MH canopy cover ..........................TASH.

Tree Dominance Type 3. Column Name: Dom 3 9 characters

Reassign dominance types identified as three species above to one of the three mixed-species classes,

also above.

IMXS—Shade-intolerant mix

TASH—Shade-tolerant subalpine fir, spruce, and mountain hemlock

TGCH—Shade-tolerant grand fir, cedar, western hemlock

For example, a three-species label of ABLA/PSME/PICO should be assigned to either IMXS or TASH.

Where ABLA is 41% and the PSME and PICO are both 21%, the remaining 17% will determine the

label—TASH if it is PIEN; IMXS if it is LAOC. 

The single-species, two-species, and mixed-species classes should be populated with an update query

later, not by the photointerpreter. 
3B-6 Existing Vegetation Classification & Mapping Technical Guide

Shrub Life Form Canopy Cover Class. Column Name: SHR_CC 6 characters

Total canopy cover of all trees, expressed as percent of the region polygon.

0

1–9

10–24

25–40

40–59

60–100

Shrub Life Form Canopy Cover Class Code. Column Name: SLFC 1 character

This field can be hidden during data entry, populated with an update query at a later date, then converted

to a .dbf and joined to region-polygon coverage for use with eCognition.

0 0%

1 1–9%

2 10–24%

3 25–40% 

4 40–59%

5 60–100%

Shrub Dominant Class. Column Name: SDom 5 characters

SRIP Shrub—Riparian

SMES Shrub—Mesic

SXER Shrub—Xeric

SSUB Shrub—Subalpine

SALP Shrub—Alpine

Grass/Forb Life Form Canopy Cover Class. Column Name: GFB_CC 6 characters

Total canopy cover of all trees, expressed as percent of the region polygon.

0

1–9

10–24

25–40

40–59

60–100

Grass/Forb Life Form Canopy Cover Class Code. Column Name: GLFC 1 character

This field can be hidden during data entry, populated with an update query at a later date, then converted

to a .dbf and joined to region-polygon coverage for use with eCognition.

0 0%

1 1–9%

2 10–24%

3 25–40% 

4 40–59%

5 60–100%
Existing Vegetation Classification & Mapping Technical Guide 3B-7

Grass/Forb Dominant Class. Column Name: SDom 5 characters

GFWET Grass/Forb—Wetland 

GFRIP Grass/Forb—Riparian

GFMES Grass/Forb—Mesic

GFXER Grass/Forb—Xeric

GFSUB Grass/Forb—Subalpine

GFALP Grass/Forb—Alpine

Nonvegetarian Life Form Canopy Cover Class. Column Name: NVG_CC 6 characters

Total canopy cover of all trees, expressed as percent of the region polygon.

0

1–9

10–24

25-40

40–59

60–100

Nonvegetarian Life Form Canopy Cover Class Code. Column Name: NLFC 1 character

This field can be hidden during data entry, populated with an update query at a later date, then converted

to a .dbf and joined to region-polygon coverage for use with eCognition.

0 0%

1 1–9%

2 10–24%

3 25-40%

4 40–59%

5 60–100%

NVG Dominance Classes. Column Name: NDom 4 characters

Select the most dominant type based on photointerpretation, independent from TM imagery. 

RCK Rock Includes scree

BAR Bare ground Includes gravel pits, sandbars

WAT Water

SNW Snow and ice

RDT Recently dead trees With foliage attached—red, orange, yellow

ODT Older dead trees Without foliage but retaining branchwood

SNG Very old dead trees Boles only, little or no branchwood

LWD Litter and down woody Tree and shrub litter fall, logs; excludes recently

debris cured annual or senescent perennial grass/forb)

BRN Recently burned

RD Nonpaved roads Native surface and gravel roads

PAV Paved roads Concrete or blacktop highways 

MAN Manmade structures Buildings 

General Comments—254 characters maximum. Record any pertinent general information such as 

region polygon delineation concerns, region polygon variability and possible effect on field sampling, and

reference data.
3B-8 Existing Vegetation Classification & Mapping Technical Guide
Existing Vegetation Classification & Mapping Technical Guide 3C-1

Appendix 3C. 

Examples of Existing Vegetation Mapping Protocols

Used To Produce Mid-Level Geodatasets

Programmatic overview of the Pacific Southwest Region process was taken from USDA

Forest Service, Pacific Southwest Region, Forest Inventory and Analysis User’s Guide,

May 2002, Chapter 200, “Vegetation Classification and Mapping.”

Project documentation was taken from USDA Forest Service, Northern Region,

Northern Region Vegetation Mapping Project Documentation (R1-VMP), 2004.
3C-2 Existing Vegetation Classification & Mapping Technical Guide
Existing Vegetation Classification & Mapping Technical Guide 3C-3

Pacific Southwest Region Process

Contents

200 Vegetation Classification and Mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3C-5

210 Conventional Versus Automated Method . . . . . . . . . . . . . . . . . . . . . . . . . . . 3C-5

220 Automated Classification of Forest Vegetation . . . . . . . . . . . . . . . . . . . . . . 3C-6

230 Modeling Ecological Relationships . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3C-7

240 Forest Canopy Modeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3C-15

250 Tree Size Class Estimations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3C-18

260 Collecting Training-Site Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3C-18

270 Integrating Remote Sensing Products In GIS. . . . . . . . . . . . . . . . . . . . . . . 3C-20

280 Accuracy Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3C-20
3C-4 Existing Vegetation Classification & Mapping Technical Guide
Existing Vegetation Classification & Mapping Technical Guide 3C-5

200—Vegetation Classification and Mapping

Assessing the condition of forests often involves maping and inventorying of vegetation.

Conventional methods use manual interpretation of stereoscopic aerial photography to

delineate areas of homogeneous vegetation (usually termed stands) using analysis of

image tone, texture, and topography. With the availability of computers and satellite

imagery, automated procedures have been developed to capture the same attributes for

delineating stands.

210—Conventional Versus Automated Method

The conventional methodology for producing vegetation maps begins with the delineation

and mapping of forest stands. Natural resource professionals skilled in air photointerpretation techniques use conventional resource photography, typically normal color, 9” x

9” positive prints at a scale of 1:15,840 or 1:24,000, to delineate forest stands by drawing

boundaries around homogeneous areas of uniform vegetation. Typically, a minimum size

of 5 acres is required for delineation. Concurrent with the delineation process, the stand

boundaries are transferred manually from the air photos to 7.5-minute topographic

quadrangles, and labels are affixed to each stand indicating the species composition,

height, crown density, and other features of interest for forest management purposes.

The stand maps thus produced are a basic information resource, widely used at the

National Forest and Ranger District levels. Because this process is based on manual

photointerpretation, it can be time consuming and costly, as well as inconsistent from

analyst to analyst.

The boundaries on the stand maps are then scanned photomechanically and entered

into an automated, computerized database through Geographic Information System

(GIS) software. Once scanned and edited, the polygons are displayed by map section

with a GIS system and stand labels are assigned. At the present time, the labeling

process is relatively costly and labor intensive.

An automated method of mapping forest vegetation has been developed over the

last 15 years using image processing and GIS technology. It was designed to overcome

the problems of conventional methods by electronically extracting and processing tonal,

textural, and terrain information from Major sources of information consist of registered

Landsat imagery, digital terrain data, and ground-based information used in map classification, stand delineations, canopy, size class, and ecological modeling.

Comparison of samples from forest strata identified by the automated method with

strata identified by conventional procedures showed that both have about the same

potential to reduce the variance of timber volume estimates over simple random sampling.
3C-6 Existing Vegetation Classification & Mapping Technical Guide

The automated method bypasses manual photointerpretation by using classification of

Landsat and registered digital terrain data. Labeling of the automatically defined classes

is still required, but can be done much more rapidly and efficiently than in the conventional

procedure. Furthermore, by utilizing image processing software systems, the classified

images, which are the analog of stand maps, can be electronically transferred through

software to the polygon-format files into GIS data bases.

220—Automated Classification of Forest Vegetation

In mapping existing vegetation for large area inventories, habitat analysis, fire fuels

modeling, and other vegetation-based information needs, four key attributes characterize

each forest stand or region: life form, species types (CalVeg), and for forest types, average

visible tree crown size, and canopy closure. Each of these attributes is characterized

independently and in a hierarchical fashion. A hierarchical approach that first classes the

most general landscape features (life form) results in a framework onto which more

detailed floristic and structural information can be added. Mapping each of these attributes

independently minimizes the confusion between attributes that have only slight image

tone and texture differences. Additionally, mapping vegetation attributes separately

allows for the application of the most appropriate classification technique. For example,

unsupervised classification has been shown to be effective for mapping life forms and

tree crown size, but relatively poor as a singular technique for vegetation type.

The basis of mapping existing vegetation with remote sensing techniques is to use

the same three characteristics of tone, texture, and terrain that the photo interpreter uses

in delineating forest stands or region boundaries, as well as life form classification.

Landsat imagery reflectance vectors provide tonal information for brightness and greenness, and Digital Elevation Model (DEM) 1:24,000 or Defense Mapping Agency (DMA)

1:250,000 digital terrain data provide the required terrain information. Texture data are

derived from Landsat imagery. The computer processing is carried out using ERDAS

Imagine, Image Processing Workbench (IPW), or similar image processing systems in

combination with ARC-INFO or other geographic information systems that support

raster- based layers. The accuracy of final vegetation maps is improved by integration of

existing GIS layers of water bodies from Cartographic Feature Files (CFFs) and mapped

areas of plantations and nonstocked forest land on wildfire areas. In a departure from the

traditional method of stand delineation, an automated, systematic method of generating

spatial, unattributed stands or regions is used. Stand delineations are independent of map

attribute classification so as to avoid reducing spatial accuracy by incorporating error

inherent in thematic classifications. Through the application of image segmentation

algorithms, consistent delineations of landscape features and growth forms are created
Existing Vegetation Classification & Mapping Technical Guide 3C-7

based on user-defined spectral and spatial parameters (see Figure 1.1). This process

allows for stand delineations to be produced more quickly and efficiently than traditional

photo interpretation techniques. Image-derived stands are subsequently combined with

vegetation attribute maps through GIS software to produce a stand-based, multi-attribute

vegetation database (see Figures 1.2,1.3).

Life form mapping is performed using unsupervised classification techniques. Tree

size class is also mapped using this technique, or in combination with supervised classification. In either case, a large number of ground observations of stands with different

average tree sizes is necessary to produce reliable maps for this attribute.

Typically, an automated, hierarchical vegetation mapping process identified vegetation

species as the next level of map information produced following life form classification.

Because forest composition varies systematically with terrain, species type can be modeled

using terrain data and ancillary GIS data. To quantify the relationship between elevation,

slope, aspect, and CalVeg type, field data is required. The simplest method of quantification

involves systematically observing each CalVeg type at all aspects, slopes, and elevations,

and plotting this on a graph. Variations in ecological relationships across a forest, geographical areas, or Natural Regions need to be identified and unique mapping rules

developed for each region. 

The structural attributes of overstory tree size and tree canopy closure are most

typically mapped following the development of life form and vegetation type information. This allows for prestratification of tree types into groups with unique and similar

physiological characteristics. The intent is to minimize confusion in mapping structural

attributes across physically variable populations. 

230—Modeling Ecological Relationships

Observations in western coniferous forest areas show that forest composition varies

systematically with topography in many places. The distribution patterns of coniferous

species have long been associated with particular elevation ranges; species are often

referred to as “low-elevation” or “high-elevation” species. Red fir, for example, is usually

considered a high-elevation species. Compass aspect (direction that a slope faces) also

influences tree growth and species distribution. North-to-northeast exposures are typically

more favorable for tree growth than drier southwestern exposures (in the northern hemisphere). As a result, species that exhibit elevational zonation tend to occur at lower

elevations on northeast-facing slopes. These terrain relationships influence climate (in

particular moisture and temperature), which in turn controls species distributions. Satellite

remote sensing is used for mapping the life forms of conifer, hardwood, shrub, meadows,

barren land, grass, and water. However, remote sensing is not particularly strong in dif-
3C-8 Existing Vegetation Classification & Mapping Technical Guide

ferentiating species or groups of species that are similar, since the variation in spectral signatures (i.e., light reflectance) can be large. Therefore, the terrain variables of elevation,

slope, and aspect are useful in modeling species associations (Macomber et al. 1991).

Natural Regions 

Because a large national forest may exhibit extensive climatic, geologic, and ecological

diversity, plant species-habitat relationships and spectral signatures that characterize

particular vegetation types are unlikely to be consistent in all portions. Therefore, the

project area is divided into Natural Regions in which ecological relationships remain

fairly constant and signature extension should be valid throughout. This not only facilitates

the accuracy of ecological type modeling within regions, but also creates serves as

“processing areas” to simplify image processing work. 

Natural Regions are defined as areas within which the elevation-aspect ranges of the

various major vegetation types remain constant. Traditionally, Natural Regions have been

designated primarily on the basis of ground reconnaissance, interviews with resource

professionals familiar with a particular area, and relevant background material (i.e., geology

maps, isohyetal maps, published documentation). Sections and subsections of the recently

implemented National Hierarchical Framework of Ecological Units (ECOMAP) are now

used to determine appropriate Natural Regions.

Digital Terrain Processing 

USGS Digital Elevation Models (DEMs) use image-processing software to derive classes

for elevation and slope/aspect. DEM images are first mosaiced to cover the area of the

Landsat TM image, then registered to the Landsat scene and resampled to match the TM

image. 

Elevation and slope/aspect images are then converted to ARC/INFO grids. Slope is

divided into four classes and aspect into three classes. Refer to Figure 2.1 by clicking on

the button below. The resultant combination classes represent incremental levels of solar

insolation with class 1 being the coolest and moistest and class 10 the hottest and driest.

Slope and aspect also affects parameters such as soil development, which exerts environmental influences on plant species composition. Where significant correlations of species

composition to soil type are observed, digital soil layers may also be used as a model input.

Building an Ecological Terrain Model 

Field training site data collected via quad maps and aerial photography forms the basis

for the ecological terrain modeling. Observations are made throughout the project area,

within each Natural Region, to sample the range of elevation/slope/aspect combinations.

Data are recorded for the occurrence of each major vegetation type at different locations

to determine the extent of a type within a Natural Region. Slope angle, elevation, and
Existing Vegetation Classification & Mapping Technical Guide 3C-9

Figure 1. Slop/Aspect Classes. Figure 2. Shrub CALVEG types.

aspect are recorded for conifer, hardwood, and shrub types that occur within a Natural

Region.

Particular attention is paid to the elevation/slope/aspect combinations where vegetation

changes within a Natural Region. For example, a Mixed Conifer-Fir forest type can

occur within an elevational band of up to 7,000 feet in a particular Natural Region. On

north aspects above 7,000 feet, red fir becomes the major type. However, red fir may not

occur on south aspects below 8,000 feet, and may not occur at all on south aspects with

greater than 60% slope. In addition to recording the elevation/slope/aspect combinations

of different vegetation types, field notes are also collected with more detail on species

composition throughout a project area. This information facilitates the development of

descriptions for vegetation types within a project area, and also supports cross-walking

between classification systems. The notes are also used to address anomalies remaining

in the map following model application.

After field data collection, the information is transferred to a matrix graph that assigns

a type to combinations of elevation and slope/aspect classes (see Figure 2). Slope is divided

into 4 classes and aspect into 3 classes (see Figure 1). These 10 classes represent increasing

levels of solar insolation, with class 1 being the coolest and moistest, and class 10 the

hottest and driest. In addition to field data, any ancillary data such as old vegetation maps,

ecological classification data, silvicultural stand exam data, etc., that exists will be utilized

to make decisions about what types occur across a Natural Region and where vegetation

types change within a matrix graph. Each Natural Region will be comprised of three matrix

graphs, one each for conifers, hardwoods and shrubs. Obviously, some generalization about

the compositions of each type and the actual “boxes” where change takes place exists;

however, this method produces better results for mapping vegetation types across large

land areas than can be achieved using spectral signatures alone.

SLOPE/ASPECT CLASSES

Class 1: Coolest & Moistest

Class 10: Hotest and Driest

High Elev. Chaparral (Huckleberry oak)

Mantane Chaparral (Manz. Ceanothus, etc.)

Low Elev. Chaparral (chamisie, etc.)

Stope-Aspect Class
3C-10 Existing Vegetation Classification & Mapping Technical Guide

Life-Form Classification. Prior to modeling ecological relationships for vegetation

type, the Landsat image is classified into several life forms: conifer, hardwoods, mixed,

shrub, wet herbaceous, dry herbaceous, barren, water, snow, agricultural, and urban.

Other more specific vegetation types that have unique spectral properties may be

mapped at this time as well.

Cloud areas are also distinguished in this step and are subsequently classified into one

of the above life forms, utilizing various techniques. Plantations are added as a separate

layer, to distinguish productive forest land from shrub, meadow, grass, or barren classes.

Water bodies are also added from Cartiographic Feature Files (CFFs), where available,

to maintain spatial consistency in lakes.

Image classification produces a “pixel-based” land cover map utilizing an unsupervised

classification technique. This technique produces spectral cluster classes known as a “per

pixel classification”. A large number of classes are produced, which are then processed by

an analyst into simpler, smaller sets and labeled with the appropriate life form.

Image classification occurs with individual pixels, not stands. Therefore, an additional step utilizes an image segmentation procedure which delineates stand boundaries,

based on spectral similarities. When combined with the per pixel classification, a “stand

based” land cover map is produced. This map is then passed through a decision rule

process, which utilizes analyst specified decision rules to label the stands or polygons,

based on the per pixel classification. Although life forms classification is based on spectral

differences, decision rules are utilized to determine conifer, hardwood and shrub polygons

from each other. The decision rules are determined by the classification system and

further influenced by the analyst who compensates for class variation within a specific

classification product. The decision rules are to label a polygon as conifer if 10% of the

tree canopy cover is conifer. If there is at least 10% conifer cover then a polygon is labeled

as conifer. If there is less than 10% conifer canopy cover, but at least 10% hardwood

cover, the polygon is labeled as hardwood. If less than 10% tree cover exists, and there

is at least 10% cover of shrubs, the polygon is labeled as shrub. Otherwise it will be

labeled as one of the other categories based on plurality. Editing is then carried out on

these stands or polygons to resolve any ambiguous results for life form. This stand life

form map is then used as input to the ecological terrain model.

In subsequent processes, stand polygon boundaries are drawn between non-conifer

areas, and between conifer areas which are at least one size class and or density class

apart. The minimum mapping unit is 5 acres for contrasting types, and 10 acres for noncontrasting types, where size or density of the inclusion area is only one class different

than the surrounding area.
Existing Vegetation Classification & Mapping Technical Guide 3C-11

Building an Ecological Terrain Model 

Field training site data is collected to form the basis for the ecological terrain modeling.

Observations are made throughout the project area, within each Natural Region, to sample

the range of elevation/slope/aspect combinations. Quad maps and aerial photography are

used to collect the data. Observations are recorded for the occurrence of each major

vegetation type at different locations to determine the extent of a type within a Natural

Region. Slope angle, elevation and aspect are recorded for conifer, hardwood and shrub

types that occur within a Natural Region.

Particular attention is paid to the elevation/slope/aspect combinations where vegetation

changes. For example, a mixed conifer-fir forest type can occur within an elevational

band of up to 7,000 feet in a particular Natural Region. On north aspects above 7,000

feet, red fir becomes the major type. However, red fir may not occur on south aspects

until an elevation of 8000 feet and may not occur at all on south aspects with greater

than 60% slope. In addition to recording the elevation/slope/aspect combinations of

different vegetation types, field notes are also collected with more detail on species

composition throughout a project area. This facilitates the development of descriptions

for vegetation types within a project area, as well as provide additional data needed for

crosswalking between classification systems. These notes are also used to address

anomolous error remaining in the map following model application.

After field data collection, the data is transferred to a matrix graph which assigns a

type to a combination of elevation and slope/aspect class (Figure 2.2). In addition to

field data, any ancillary data such as old vegetation maps, ecological classification data,

silvicultural stand exam data, etc., that exists will be utilized to make decisions about

what types occur across a Natural Region and where vegetation types change within a

matrix graph. Each Natural Region will have three matrix graphs completed, one each

for conifers, hardwoods and shrubs. Obviously, there is some generalization about the

compositions of each type and the actual “boxes” where change takes place; however,

this method can improve the results for mapping vegetation types across large land

areas, than with using spectral signatures alone.

CalVeg is the classification system being used for the mapping of existing vegetation.

After the types are plotted on matrix graphs and separated in slope-aspect-elevation

space, rules for the prediction of CalVeg types are developed. The input for the rules are

the elevation maps and the slope/aspect maps that were already created in IPW and ARC.

These “rules” produce a separate “map” for conifers, hardwoods and shrubs within each

Natural Region. This map represents the potential for finding a particular existing vegetation type at the specified elevation and slope/aspect class, based on field training site

data and ancillary ecological information.

The final step is to combine these layers with the stand based cover map which

represents life form for the area. These layers become the inputs to which the modeling
3C-12 Existing Vegetation Classification & Mapping Technical Guide

rules are applied. The actual model application is performed in ARC/GRID using ARC

macro language (AML) scripts which can be easily modified if rule refinements are

necessary. Subsequent AML outputs become the draft vegetation type or CALVEG layers

that are field reviewed and, if necessary, revised before integration into the final map

products. In this way, all conifers, hardwoods and shrubs, within a Natural Region, are

assigned a specific type or series level label of the CALVEG classification system based

on these rules. Meadows and dry grass were previously broken out during life form image

classification and polygon formation, and do not undergo more specific identification.

The basic process is to intersect separate layers in a geographic information system; the

life form layer together with each model layer representing the potential types for

conifers, hardwoods and shrubs. 

Not all vegetation types can be modeled with terrain data. Examples include vegetation growing on serpentines, and those with specific moisture or soil requirements, such

as lodgepole pine. In these cases, ancillary information is sought to delineate where these

areas can occur. Resource professionals from the national forests very often have mapped

these areas or know where they are. In such cases, these are brought in as another GIS

layer that then supercedes the results of the ecological terrain model. The quality of

vegetation type maps produced from remote sensing can be greatly improved with specific

information derived from ancillary data, both in the use of building the terrain model,

and to delineate types that are not as directly influenced by terrain variables. In some

cases, ecological modeling may consider differences in soils or geology as variables to be

input into type modeling, particularly in areas where terrain does not strongly influence

vegetation compositions. Increasingly, environmental variables known to drive vegetation

distribution are being captured and maintained as digital information. As these data are

developed and become available, the predictive accuracy of ecological models.may

increase.

CALVEG Classification System

The CalVeg Classification of California Vegetation system was initiated in January 1978

by the Region 5 Ecology Group of the U.S. Forest Service with headquarters in San

Francisco. The acronym means Classification and Assessment with Landsat of Visible

Ecological Groupings. The CalVeg team’s mission was to classify California existing,

rather than potential, vegetation communities for use in statewide resource planning

considerations. This was accomplished with the use of color infrared satellite imagery and

field verification of types by current soil-vegetation mapping efforts as well as professional

guidance through a network of contacts throughout the state. Maps were produced at a

statewide scale of 1:1,000,000 in electronic format as well as regional maps at scales

of 1:250,000 produced as overlays to existing baseline or “sheet” maps at that scale. It

was one of the earliest statewide vegetation coverages easily available for computerized
Existing Vegetation Classification & Mapping Technical Guide 3C-13

mapping efforts and was considered to be useful for landscape level, watershed level or

coarser scale applications, such as forest level planning and analysis. The first maps produced under this classification using current remotely sensed imagery and methods

were those of the southern Sierra national forests in the mid-1980s at an image resolution of 30 meters or greater. Some of these older maps have been updated one or more

times in the interim period.

Whereas regional forest types are groupings used for forest canopy modeling,

inventory and general planning, the CALVEG classification can be more suitable for

multiple-use resource information needs of the National Forests. The key in Appendix B

can serve as criteria for separating CALVEG types from each other. More detailed

descriptions are available in the U.S. Forest Service document CALVEG: A Classification

of California Vegetation. Some descriptions have been refined further than what is in

this document, to provide more specificity of type descriptions for particular National

Forest mapping projects.

Regional Forest Type

Regional forest type is a level of classification used to divide forests into broad categories based on species composition. The underlying reason for the differentiation of

regional types is that forest stands of tree size and canopy density characteristics, but

different regional types, will have different timber volumes. Regional types are typically

defined by the dominant species in the stand; for example: red fir, Douglas fir, ponderosa pine, or simply mixed conifer. This broader grouping is useful in modeling forest

canopy geometry, where average crown width and length for a regional forest type with

a common mix of tree species can be estimated.

The field graphs used to define CALVEG types by Natural Regions are also used in

modeling regional forest type, by grouping closely related CALVEG types into regional types.
3C-14 Existing Vegetation Classification & Mapping Technical Guide

231—Field Notes Record

Major Vegitation Type – Field Notes

Date:______________ Observer:________________________________________________________

Observation

Quad No.: ___________ Point No. : ____________ Photo No.: ___________ Slope: _____________

Aspect: _____________ Elevation: ____________

Overstory Overstory

Total Tree Total Conifer

Canopy Cover % : __________________________ Canopy Cover % : __________________________

Overstory Total Total Shrub

Hardwood Canopy Cover % : _________________ Cover % : ________________________________

Total Herb Cover %: ________________________

(Forbs/Graminoids/Ferns)

Species %Cover Species %Cover

Overstory _______________ _______________ Shrubs ______________ ______________

Conifers _______________ _______________ ______________ ______________

_______________ _______________ ______________ ______________

_______________ _______________ ______________ ______________

_______________ _______________ ______________ ______________

_______________ _______________ ______________ ______________

_______________ _______________ ______________ ______________

_______________ _______________ ______________ ______________

Hardwoods _______________ _______________ Forbs Ferns/ ______________ ______________

_______________ _______________ Grasses ______________ ______________

_______________ _______________ ______________ ______________

_______________ _______________ ______________ ______________

_______________ _______________ ______________ ______________

_______________ _______________ ______________ ______________

_______________ _______________ ______________ ______________

_______________ _______________ ______________ ______________

CalVeg Type _______________________________ WHR Type ______________________________
Existing Vegetation Classification & Mapping Technical Guide 3C-15

240—Forest Canopy Modeling

The Canopy Model

Canopy modeling is accomplished using geometric modeling procedures. The canopy

model is used to obtain estimates of “treeness” or values of “M,” which are in turn

inverted to give estimates of canopy closure as percent cover values for each forest

stand or region. The four-component canopy model consists of sunlit tree crowns, sunlit

background, shaded tree crowns, and shaded background (see Figure 2.3). This mixed

model mimics the light sources contributing to reflectance values for each 30-meter

pixel area of a Landsat image brightness-greenness band combination and its varience

between pixels within a stand. 

Compensating for Illumination

Most National Forest land being classified contains rugged terrain. Terrain effects how

the sunlight is reflected or absorbed by an object or surface and the intensity of the sunlight received, causing increased variance in the spectral values of the Landsat image.

The variation is produced by differential illumination of slopes (i.e., shadows) caused by

high topographic variation combined with low sun angle at the time of observation of

the Landsat overpass. To minimize this effect, image dates are obtained for mid-to-late

summer, when the sun is the highest and the shaded slopes receive the most sunlight.

Even so, the more densely stocked forest areas with normal illumination have the same

spectral reflectance as more sparsely stocked stands in poorly illuminated or shaded

areas. This problem rules out the separation of forest canopy attributes based solely on

spectral reflectances. Thus, it is necessary to develop a means of separating the image

into categories based on illumination conditions at the time of the Landsat overpass.

The registered terrain data are used to model illumination conditions for each pixel

within a stand or region. The angle between a normal-to-the-land surface and the sun at

the time of the Landsat overpass is calculated. For a diffuse (Lambertian) reflector, the

apparent brightness of a surface under constant illumination at angle z will be proportional

to cos(z). Thus, a cos(z) image displays the brightest values for pixels directly facing the

sun, and the darkest values for pixels in shade. From the cos(z) image, a mask is created

to divide the image into two categories based on illumination: well-illuminated, and

poorly illuminated (shaded). The cutoff between these two categories is a zenith angle

of 60°; areas with angles greater than 60° are considered poorly illuminated.

The mask of shaded and well-illuminated pixels is created and serves to divide the

area being mapped into its shaded and unshaded components. Since only a small percent

of the image will be shaded, however, many classes remain undivided. The result of this

action is to reduce within-class variation effectively and remove a potentially adverse

effect on the predictive process.
3C-16 Existing Vegetation Classification & Mapping Technical Guide

Canopy Model Inputs

The canopy model requires several kinds of information: Landsat imagery, time and

location of the satellite when the image was taken, topography of the stands, average

proportion of crown length to crown radius by regional forest type, and component signatures from known locations with known values for the model components (see Figure 3).

The Landsat image is recombined as two transformations, brightness and greenness.

These are used in both the signature estimation procedure and as values for each pixel in

a forest stand. The time and location of the satellite are used to calculate the local solar

zenith, and also in combination with the slope and aspect information to determine the

surface geometry of each stand.

Data collected from a number of individual stands are used to calibrate the component

signatures of the canopy model, shaded and sunlit crowns, and background for each

regional forest type. The information also supports development the tree geometry

parameters of crown length to crown radius, b to r ratio (see Figure 4).

For each Regional Forest type, the crown model is calibrated using detailed information

for known stands and then run across the entire map area for all pixels within stands.

For all stands labeled with the same regional type, an estimate of M, or treeness, is

determined for each pixel, and then inverted to obtain estimates of canopy cover for

each stand (see Figure 5).

Figure 3. Hypothetical location in feature

space of four components of the model: illumunated crown (C), shadowed background

(T), illuminated background (G), shadowed

background (Z), and the coverage trajectory

from the background (G) to X∞.

Figure 4. Simple spheroid model of a conifer

tree in the canopy reflectance model. r = radius

of crown; b = half - height of crown; h = height

of stem; 0 = solar zenith angle; A(0) = area of

shaded background.
Existing Vegetation Classification & Mapping Technical Guide 3C-17

Figure 5. Forest Vegetation Mapping Scheme.
3C-18 Existing Vegetation Classification & Mapping Technical Guide

250—Tree Size Class Estimations

Estimating average tree size class is the hardest stand attribute to obtain from imageprocessing techniques, or directly from aerial photos. Several factors, none of which are

totally independent, tribute to the difficulty. Aerial photos capture visible crowns from a

“birds eye view”; from this angle, portions of the tree crowns are hidden from view by

the shadowing and overlapping of trees in the upper canopy; thus, only part of what is

actually in a forest stand—the visible crown diameter of the top story trees—can be

measured directly on aerial photos. Because crown diameter and tree diameter at breast

height (DBH) are highly correlated, estimates of tree size can be made by measuring

their crowns. However, the relationship of crown width to DBH relationships do vary by

species, especially for hardwoods compared to conifers. The other key factor causing

estimation errors in average tree size occurs when in mixed stands, when trees vary

from large to small. This is the case for many stands found in California due to fire,

pests, and harvesting history. 

When estimating tree size using Landsat imagery, a large number of training stands

are required to overcome this problem. Most of the reflected light received from the

ground to the satellite is a function of tree canopy cover, not tree size. Although tree size

does affect the texture of the image, it also affects the measure of variance of neighboring

pixel values where the larger the variance value, the larger the trees; this same effect can

occur from clumped small trees with bright background areas between the clumps. This

problem causes confusion of large trees with small trees.

The most reliable procedure for mapping average tree size is unsupervised classification. All pixels classified as trees are now reclassified for tree size using the information

from known stands that are homogenous. The focus of the classification is to separate

the small pole-size trees from the large timber-size trees, and default the remaining into

the medium-size class. Although this procedure is not as exacting as doing detailed

measurements on aerial photos or in-place stand exams, it does produce a useable map

when combined with the plantation layer for the smaller seedling, sapling, and pole

stand sizes.

260—Collecting Training–Site Information

Field Data Collection—Canopy/Size

It is important to have accurate field data in each of the major forest types in order to

model canopy cover and conduct unsupervised classification for classes. Our approach

is to model canopy cover based on the geometry of forest canopies and the position of

the sun. This approach allows for variation in the bidirectional reflectance of forest
Existing Vegetation Classification & Mapping Technical Guide 3C-19

canopies and the effects of sun angles, surface topography, background vegetation, and

shadowing. Field data must, therefore, reflect the range of conditions that are encountered

within a project area. 

Major forest types (conifers and hardwoods) for the project area are identified ased

on field reconnaissance, published material, and discussion with knowledgeable local

experts. Major forest types correspond to CALVEG Series Level types; for example, red

fir, eastside pine, blue oak, etc. Training stands are chosen as representative samples of

each major forest type, on illuminated, shaded, and flat slopes. Illuminated slopes are those

at a south-southeast aspect with a greater than 30% slope; shaded are on north-northwest

aspects and greater than 30% slope; and flat are those with less than 20% slope. This

describes the mid-range of possible illumination conditions (flat) and the two extremes

(shaded and illuminated) for calibrating the canopy model. 

Training stands are further stratified by canopy cover class: 10-30%, 31-69%, and

greater than 70% canopy closure. Training stands are chosen with aerial photography

interpretation to determine if they meet the sets of condition described above. In addition,

they should be at least 10 acres in size and homogenous in canopy cover. Further verification of

training stands that meet the above set of conditions occurs in the field before data collection.

For each canopy model training site, a 16-point grid is installed, with points located

at equal distances from each other (Quick Plot Stand Exam, see Section 374 for plot

configuration). The distance between points varies with the size of the stand, to sample

all portions of the area. At each point, information on elevation, slope and aspect is

recorded. A variable-radius plot is used, and for all trees that fall into the plot, species,

crown position, crown ratio and diameter at breast height (DBH) are recorded. At each

point, one tree first tree from north will also have height and crown diameters measured.

Two site trees are located within each training site, to core for age and determine the

site index for the stand. Information is also collected on “background” found beneath

the canopy, including percent cover of seedlings, saplings, shrubs, forbs and grasses,

and any ground material (rock, duff, etc.) that may be present.

Size canopy training sites must also include a range of all major forest types in the

project area on illuminated, shaded, and flat conditions across 4 size class groups. These

classes are for poles (6-12” DBH), small trees (12-24” DBH), medium trees (25-36” DBH),

and large trees (greater than 40” DBH). Again, each training site must be at least 10 acres

in size, and fairly homogenous with regards to size class. Stands should also be singlestoried, even-aged stands, with moderate crown density. No field data are collected,

since they are used for an unsupervised classification, not a modeling technique. The

stand is delineated on aerial photographs and topographic quadrangles, and information

on type (species composition), tree size class, and illumination angle are recorded.

Training site data are processed and summarized using the USFS Region 5 Forest Inventory

and Analysis System software for input into the canopy model and size classification.
3C-20 Existing Vegetation Classification & Mapping Technical Guide

270—Integrating Remote Sensing Products In GIS

Unlike the conventional method of vegetation mapping where the stand maps must be

photo-to-map transferred, scanned, or digitized and labeled, the automated classification

data file is converted from pixel format (raster) to polygon format (vector). Most GIS

software can accommodate this as a standard routine. The resulting vegetation map is

now a layer in the GIS data base that may be overlaid with administrative, compartment,

and/or watershed boundaries. If plantations, nonstocked forest areas from fires, and/or

water bodies have not been incorporated during the mapping phase, they can now override

these areas by using the GIS software to update the vegetation maps. Once the map

update and overlay process is complete, net National Forest acre values can be calculated

for each unique vegetation label or attribute of interest, broad life form, or CALVEG type.

Maps can be easily produced for use in forest inventory, land management planning,

watershed analysis, or landscape analysis projects.

280—Accuracy Assessment

All vegetation type maps contain errors. It is impossible to create absolutely accurate

delineations between vegetation types, largely because vegetation does not grow in

homogenous patches or stands. By nature, vegetation boundaries are likely to be diffuse,

or fuzzy, rather than sharp and contrasting. Errors can be of several types. Errors of

omission occur when “conifers are mapped as something other than conifers.” Conversely,

an error of commission occurs when “shrubs are mapped as conifers.” Registration errors

can affect large areas of a map, causing the boundary lines to be shifted in one direction.

Accuracy assessment of maps improves their utility by providing the user with

information about the nature, magnitude, frequency, and source of errors. If the user

knows that some of the conifers are mapped as something other than conifer, it will help

explain why the total acreage of conifer falls short of expected values. On the other

hand, if the acreage of conifer seems excessive, it could well be because many of the

shrubs were mapped as conifer. An accuracy assessment can be conducted in a variety

of ways, but the two primary methods are the Error Matrix and the Fuzzy Set.

An error matrix involves comparing mapped labels with on-the-ground conditions

at the site. The observer has only to determine if the mapped label is right or wrong. If

the mapped unit is “conifer” and the observer finds shrubs, it counts as an error. A matrix

table is constructed using mapped labels on one axis, and observed conditions on the

other axis. The higher the proportion of “matches” there are, the more accurate the map.

The error matrix is sometimes referred to as a “Confusion Table” because it can highlight
Existing Vegetation Classification & Mapping Technical Guide 3C-21

the types that are often confused. If 25% of the sites labeled conifer actually contain

shrubs, then it can be inferred that a high level of confusion exists between conifer and

shrubs.

Fuzzy Set theory goes a step beyond looking at right vs. wrong and confusion. It

requires that the observer, without knowledge of the map label, make an unbiased

evaluation of the site and rate all possible labels on a relative scale from “absolutely

right” to “absolutely wrong.” For example, if the observer was evaluating a pure red fir

stand, he/she would rate a label of “hardwoods” as absolutely wrong, but might rate

“mixed conifer-fir” as wrong, but close. Or a shrub/hardwood site might get an OK

rating for either the “shrub” or “hardwood” label, but would receive “absolutely wrong”

for a conifer label.

The benefit of using Fuzzy Set accuracy assessment is that it provides more information about the nature, magnitude, and location of errors. Below is an example from

the accuracy assessment recently completed on a forest mapping project:

Polygons labeled conifer can reliably be expected to be conifers except on

steep, northwest-facing slopes where confusion with hardwoods may occur.

Regardless of how carefully a vegetation map is prepared, errors will always occur.

An accuracy assessment is essential to provide the user with the necessary information

to interpret the map wisely. Forest inventory information can be used in the preparation

of accuracy assessments, as long as all unique vegetation types and conditions are sampled

in a nonbiased fashion.
3C-22 Existing Vegetation Classification & Mapping Technical Guide
Existing Vegetation Classification & Mapping Technical Guide 3C-23

Northern Region Vegetation Mapping 

Project Documentation

Contents

Executive Summary ................................................................................................3C-24

1.0 Introduction ........................................................................................................3C-26

2.0 General Relationship of Classification, Mapping, and Inventory .....................3C-30

3.0 Vegetation Classification ...................................................................................3C-32

3.1 Physiognomic and Floristic Classification..................................................3C-34

3.2 Tree Diameter Classification ......................................................................3C-36

3.3 Tree Canopy Cover Classification ..............................................................3C-36

4.0 Map Design ........................................................................................................3C-37

4.1 Physiognomic and Floristic Map Design ....................................................3C-37

4.2 Tree Diameter Map Design.........................................................................3C-38

4.3 Tree Canopy cover Map Design..................................................................3C-39

4.4 Minimum Map Feature................................................................................3C-39

5.0 Vegetation Mapping ...........................................................................................3C-39

5.1 Acquisition and Preprocessing of Image and Ancillary Data.....................3C-40

5.2 Ecogeographic Stratification.......................................................................3C-41

5.3 Image Segmentation....................................................................................3C-43

5.4 Change Detection ........................................................................................3C-45

5.5 Ecological Modeling and Other Ancillary Data..........................................3C-46

5.6 Reference Data ............................................................................................3C-47

5.7 Hierarchical Classification..........................................................................3C-49

5.8 Mosaic Subpath Data Models .....................................................................3C-51

5.9 Accuracy Assessment..................................................................................3C-51

6.0 Vegetation Inventory ..........................................................................................3C-55

7.0 Maintaining Existing Vegetation Maps and Associated FIA Data ....................3C-57

Literature Cited.......................................................................................................3C-59
3C-24 Existing Vegetation Classification & Mapping Technical Guide

Executive Summary

Existing vegetation is the primary natural resource managed by the USDA Forest Service

and by most forest landowners and land management agencies. The agency is charged

with managing vegetation for a variety of human uses while maintaining the integrity of

ecosystem components and processes at national, regional, and local scales. Development

of consistent and continuous current vegetation data of sufficient accuracy and precision

to address the principal resource concerns supports ecosystem assessment and land

management planning. Many of the analyses needed to address multiple resource issues

are essentially analyses of vegetation pattern and process relationships. These vegetation

analyses support a variety of Forest Service business needs, including:

• Forest planning, including revision and amendment of existing plans 

• Forest-level and regional fuels assessments for implementation of the National Fire

Plan 

• Ecosystem assessment at the watershed scale of all lands within a watershed

(4th/5th HUC EAWS), independent of ownership

• Resource Planning Act reporting requirements

• Forest and rangeland assessments 

• Postfire assessments

• Project-level cumulative effects analyses

Responding to these business needs, the Regional Forester’s Team tasked the

Northern Region, Resource Information Management (RIM) Board to develop a plan to

map current vegetation west of the Continental Divide. The Northern Region Vegetation

Mapping Project, hereafter referred to as R1-VMP, was designed to meet this identified

need (see Figure 1). 

Figure 1.— Northern Region Vegetation Mapping Project area.

USDA Forest Service

Private / Other

National Park Service

Tribal Lands

State Land

Wildlife Management Areas

Water

N

Canada

Montana

Washington

Oregon

Idaho

0 75 150 300 Kilometers

Vicinity Map
Existing Vegetation Classification & Mapping Technical Guide 3C-25

The Regional Forester’s Team had two programmatic objectives for R1-VMP:

1. Produce a consistent and continuous geospatial database for existing vegetation and

associated attributes covering the northern Idaho and western Montana portions of

the Northern Region. These data will be continuous across all ownerships and be

produced following a consistent methodology; they will also be compatible with the

recently completed SILC3 vegetation-mapping project for the eastside of the

Northern Region, as well as recent national standards for vegetation classification

and mapping.

2. Develop remote sensing and spatial analysis skills on each forest to facilitate long-term

use and maintenance of these datasets. The skills and experience gained by forestlevel employees will provide the basis for forest-specific refinements of the regional

data and specialized analysis support.

Based on an remote-sensing applications, R1-VMP was developed with the following

design elements:

• Utilization of ECOMAP section-level delineations to limit the variance associated

with vegetation types within the study area.

• Extensive use of ancillary data and ecological modeling to improve classification results.

• Extensive use of summer and fall Landsat TM data to exploit seasonal variation in

vegetation and other land cover classes.

• Utilization of TM image segmentation and merge procedures to create base classification units. 

• Utilization of hierarchical classification to provide a consistent linkage between the

lower levels commonly used by the agency and the upper levels required by the Federal

Geographic Data Committee (FGDC) Vegetation Classification Standards (VCS). 

• Generation of training and accuracy assessment data through a structured aerial

photo interpretation process. 

The result of R1-VMP is a geospatial database used to produce four primary map

products for life form, tree canopy cover class, tree diameter, and dominance type. Map

products have a variable minimum map unit (MMU) size varying from 1 acre for water

features, 2.5 acres for grass-forb and shrub, to 5 acres for tree land cover. The geospatial

database can be used as needed to construct user-specified map themes at varying MMU

to aid in the analysis of management questions related to forest vegetation. The details

of database and map product development and accuracy assessment are included in the

project report.

A maintenance and update strategy annually identifies areas of changed conditions

for systematic updates of the R1-VMP data. 
3C-26 Existing Vegetation Classification & Mapping Technical Guide

1.0 Introduction

Existing vegetation is the primary natural resource managed by the USDA Forest Service

and most forest landowners and land management agencies. The agency is charged with

managing vegetation for a variety of human uses while maintaining the integrity of

ecosystem components and processes at national, regional, and local scales. One of the

most fundamental information needs to support ecosystem assessment and land- management planning is consistent and continuous current vegetation data of sufficient

accuracy and precision to address the principal resource concerns. The primary ecosystem

component managed is vegetation. Other ecosystem components, such as water, soil,

fuels, and air quality, as well as terrestrial and aquatic fauna, are managed indirectly by

way of vegetation management and/or access management. Much of the data needed to

address multiple resource issues are derived from vegetation pattern and process analyses.

These vegetation analyses are used to support a variety of Forest Service business needs

including:

• Forest planning, including revision and amendment of existing plans 

• Forest-level and regional fuels assessments for implementation of the National Fire Plan

• Ecosystem Assessment at the Watershed Scale (EAWS) that assess all lands within a

watershed (4th/5th HUC EAWS), independent of ownership

• Resource Planning Act reporting requirements

• Forest and rangeland assessments 

• Postfire assessments

• Project-level cumulative effects analyses.

Maps are the most convenient and universally understood means of graphically representing the spatial arrangement and relationships among features on the earth’s surface

(Mosby 1980). A map is indispensable for recording, communicating, and facilitating

analysis of such information relating to a specific area. Accurate and up-to-date maps

of existing vegetation are commonly used for inventorying, monitoring, and managing

numerous resources on National Forests (e.g., wildlife habitat), including the business

requirements listed above. Recognition of the importance of map products to support

this wide variety of business needs was a primary consideration in identifying existing

vegetation as a national Geographic Information System (GIS) layer for the Forest

Service. This same recognition resulted in the development of the Existing Vegetation

Classification and Mapping Technical Guide (Brohman and Bryant 2005) to establish

Forest Service standards and procedures for classification and mapping of existing vegetation. This technical guide is authorized by Forest Service Manual (FSM) 1940 and has

been developed according to direction in Forest Service Handbook (FSH) 1909. These

standards were developed to guide the development of future classification and mapping
Existing Vegetation Classification & Mapping Technical Guide 3C-27

products following the Federal Geographic Data Committee (FGDC) vegetation classification standards and provide a hierarchical approach to map unit design. 

Ecosystem assessment and land management planning at national and regional scales

require consistent standards for classification and mapping of existing vegetation. Such

standards have never been developed because, until recently, most Forest Service planning

and management standards have focused on issues at the local scale. The breadth of the

Forest Service mission necessitates that classification and mapping protocols be designed to

deal with a wide range of issues. The agency cannot develop a separate classification and/or

map for every question land managers face. The agency must, therefore, describe and map

fundamental units of vegetation that can be interpreted to address numerous questions. This

requires hierarchical classification and multiscale mapping so existing vegetation can be

described and mapped at the appropriate level of detail for each issue. 

Historically, vegetation inventory and mapping have been conducted through some

form of two-stage sampling of forest stands. The term stand has long been used to refer

to the basic unit of forest management (Toumey 1937); therefore, it has been used as the

basic unit of mapping and inventory (Graves 1913). A stand is defined as “a community,

particularly of trees, possessing sufficient uniformity as regards composition, age, spatial

arrangement, or condition, to be distinguishable from adjacent communities, so forming

a silvicultural or management entity” (Ford-Robertson 1971). This process normally

consisted of the delineation of “timber stands” with stereo, vertical aerial photography.

The basis for delineation of stands was discontinuities in texture (reflecting stocking

and crown size differences) or apparent tree height (Stage and Alley 1972). 

The second stage was normally field sampling of the delineated stands or a stratified

random sample with subsequent inference of field-sampled strata characteristics to

unsampled stands within the strata. This process also involved transferring the photo

delineations to a base map. These stand delineations reflected management considerations,

as well as vegetative composition and structure. They often included several vegetation

types that were different in terms of composition and structure, but were similar in terms

of management implications and/or history. The term “stand” was also extended to describe

nonforest vegetation, rock or barren areas, or water bodies. Although extending the standmapping concept made these maps more comprehensive, it did not map fundamental

units of vegetation that could be interpreted to address numerous questions. Additionally,

these maps represent a dynamic ecosystem component and have a finite period of currency.

The intent with this inventory and mapping strategy was to regularly update the data,

normally every decade. 

Figure 1 illustrates the status of stand exam based inventory data for the Northern

Region and the “decay curve” associated with trends in inventory data by displaying a

10-year periodic total that filters out “stale” inventory data from the total. These data

apply almost exclusively to the suitable timber base, as defined by the National Forest
3C-28 Existing Vegetation Classification & Mapping Technical Guide

Management Act of 1976 (US Public Law 94-588 1976). The remaining areas outside

the suitable base have few stand exam-inventory data, even though many of the questions

and issues apply to all lands. In addition, there are no specific design considerations for

the collection and storage of these data to facilitate their use by other land management

agencies or private landowners. 

Responding to this information need, the Northern Region Resource Information

Management (RIM) Board developed a plan to provide for a regional resource information

capability, commiting the region to a prioritized set of projects for the next 3 years. The

Regional Forester’s Team approved the RIM Board’s recommended plan, and the board

identified a number of corporate datasets and information systems as priorities, including

resource mapping and development of a GIS core layer for current vegetation. The

Northern Region Vegetation Mapping Project, hereafter referred to as R1-VMP, was

designed to meet this need. The project design was accepted by the RIM Board to be

completed as a 3-year project beginning in March of 2001.

The Regional Forester’s Team had two programmatic objectives for R1-VMP:

1. Produce a consistent and continuous geospatial database for existing vegetation and

associated attributes covering the northern Idaho and western Montana portions of the

Northern Region. These data will be continuous across all ownerships and be produced

following a consistent methodology. They will also be compatible with the recently

completed SILC3 vegetation-mapping project for the eastside of the Northern Region,

as well as recent national standards for vegetation classification and mapping.

2. Develop remote sensing and spatial analysis skills on each forest to facilitate long-term

use and maintenance of these datasets. The skills and experience gained by forestlevel employees will provide the basis for Forest-specific refinements of the

Regional data and specialized analysis support.

Figure 1. USDA Forest Service, Northern Region, stand exam program status summary for 1980-2001.
Existing Vegetation Classification & Mapping Technical Guide 3C-29

The first objective of R1-VMP was to provide the Northern Region and cooperating

agencies with a geospatial database of vegetation and land cover based on consistent

analytical logic and methods, and mapped continuously across all ownerships. This

geospatial database with its associated inventory data supports land management planning

and sustainable forest management at regional, subregional, and landscape assessment

scales. These data also provide the analytical basis for vegetation pattern and process

analyses associated with forest management planning. It is also explicitly designed to

provide for project-level analyses using the same analytical logic and scale-appropriate

methods. This design element facilitates establishing the relations among individual

projects and Forest-wide or Regional management direction. These data should also

facilitate cumulative effects analyses for many projects. The project area for R1-VMP

covers all ownerships and encompasses approximately 27,000,000 acres (11,000,000

hectares) of the USDA Forest Service, Northern Region (Figure 2). The area extends

from the Continental Divide to the Washington and Oregon borders, and from the

Salmon River to the Canadian border.

The second objective was accomplished through a team concept that draws on multiple

organizational levels within the region. Within this structure, regional office personnel

provide overall project coordination and oversight, as well as technical assistance, training,

and specialized skills. Forest personnel provide the local field experience and specialized

skills needed to produce a quality product and develop the knowledge and experience

needed to effectively utilize and improve these data for forest- and project-level analysis

objectives. 

In the early stages of the project it became increasingly obvious that R1-VMP was

not a mapping project but, in fact, a classification, mapping, and inventory project. The

R1-VMP team needed to facilitate the discussion with the Northern Region Vegetation

Council regarding the evaluation and adjustment of the existing regional classification

Figure 2. Northern Region Vegetation Mapping Project area.

USDA Forest Service

Private / Other

National Park Service

Tribal Lands

State Land

Wildlife Management Areas

Water

N

Canada

Montana

Washington

Oregon

Idaho

0 75 150 300 Kilometers

Vicinity Map
3C-30 Existing Vegetation Classification & Mapping Technical Guide

logic. Numerous problems had been identified with the classification logic and associated

algorithms used in the SILC projects and concerns had been expressed that the classes

were not exhaustive and/or mutually exclusive. Additional concerns regarding the eventual

integration of the map products with some form of inventory data were also raised.

Coordination with the Northern Region Vegetation Council and the Regional Forest and

Rangeland staff resulted in the modification of this project to accomplish these longer-term

objectives. Accordingly, this project documentation describes the general relationship of

vegetation classification, mapping, and inventory followed by sections describing each

of these processes relative to R1-VMP. The following project documentation tiers to and

expands on the Existing Vegetation Classification and Mapping Technical Guide (Brohman

and Bryant 2005). Particularly relevant sections of the technical guide are included here

directly, rather than incorporating by reference.

2.0 General Relationship of Classification, Mapping, and Inventory

As discussed in the introduction, one of the most fundamental information needs for

implementing any sustainable forest management strategy is consistent and continuous

current vegetation data of sufficient accuracy and precision to address the principal

issues and resource concerns. Many of the analyses needed to address multiple resource

issues are essentially analyses of vegetation pattern and process relationships. All of these

analyses rely on the data models produced from vegetation classification, mapping, and/or

inventory. R1-VMP is designed to utilize these three types of data models to provide

robust existing vegetation information for a wide variety of analysis applications. It is

important, however, to remember the caution of the distinguished statistician George

Box who observed “All models are wrong—but some models are useful.” Useful is

therefore defined by the ability of these data models to address an intended analysis

application. The following sections describe the classification, mapping, and inventory

logic/methods of the R1-VMP data. Users of these data should evaluate R1-VMP in the

context of the intended use.

A number of significant terms are commonly associated with vegetation classification,

mapping, and inventory. These terms are defined in order to ensure a clear and consistent

discussion of the concepts and relationships presented in this project documentation.

Existing vegetation is the plant cover, or floristic composition and vegetation structure, occurring at a given location at the current time. 

Classification is the process of grouping of similar entities into named types or

classes based on shared characteristics. A vegetation type is a named category of plant

community or vegetation defined on the basis of shared floristic and/or physiognomic

characteristics that distinguish it from other kinds of plant communities or vegetation.
Existing Vegetation Classification & Mapping Technical Guide 3C-31

Taxonomic units are the basic set of classes or types that comprise a natural or scientific

classification. Taxonomic units can be developed for physiognomic classifications (e.g.,

tree-dominated classes or shrub-dominated classes) or floristic classifications (e.g., dominance-type classes or plant association and alliance classes). Taxonomic units represent

a conceptual description of ranges and/or modal conditions in vegetation characteristics.

Technical groups are the basic set of classes or types that comprise a technical classification. Technical groups can be developed for structural classifications (e.g., canopy cover

classes and/or tree size classes). Technical groups represent a conceptual description of

ranges and/or modal conditions in vegetation characteristics. 

Vegetation mapping is the process of delineating the geographic distribution, extent,

and landscape patterns of vegetation types and/or structural characteristics. A vegetation

map unit is a collection of areas with a common definition and name reflecting their

component taxonomic units and/or technical groups. Units depicted on maps within

individual areas or delineations that are non-overlapping and geographically unique are

referred to as map features (e.g., polygon delineations or region delineations). Thematic

resolution is the level of categorical detail present within a given set of map units. In a

general sense, increased thematic resolution is represented by an increase in the number

of map units and fewer map units conversely represent coarser thematic resolution.

While thematic resolution is often implied by geographic or spatial resolution, a direct

relationship is not inherent.

Vegetation inventory is the process of applying an objective set of sampling methods

to quantify the amount, composition, and condition of vegetation within specified limits

of statistical precision. 

These three processes and the resulting data models are integrally related, but they

are separate. Vegetation classification defines and describes vegetation types and/or

structural characteristics (i.e., what is it?). Vegetation mapping spatially depicts the

distribution and pattern of vegetation types and/or structural characteristics (i.e., where

is it?). Vegetation inventory quantifies the amount, composition, and condition of

vegetation (i.e., how much is there?). The conceptual relationships between classification,

mapping, and inventory are schematically depicted in Figure 3. 

A one-to-one relationship between vegetation types (from a classification) and

vegetation map units is uncommon given the limitations of mapping technology and the

level of floristic detail in most classifications. Mapping, therefore, usually entails trade-offs

among thematic and spatial resolution and accuracy, as well as cost. The goal is constrained

optimization, not perfection. This problem is reduced somewhat when vegetation types

(such as dominance types), and structural classifications are designed to be applied to

mapping projects. Similarly, there is rarely a sufficient sample size to quantify all vegetation types. Inventory compilation usually involves tradeoffs to generalize and aggregate

vegetation types and/or structural classes to achieve the sample size needed to provide

estimates consistent with the intended analysis applications. 
3C-32 Existing Vegetation Classification & Mapping Technical Guide

Because these ecosystems are dynamic, evolutionary, and have limited predictability,

many of the analyses needed for ecosystem management strategies require a variety of

simulation models. The majority of these simulation models rely heavily on accurate and

relatively detailed vegetation data (e.g., SIMPPLE, WATSED, and FARSITE). These models

vary in the specificity and detail of vegetation data needed, but most require continuous

spatial data with consistently classified attribute data. Classification, mapping, and inventory

each contribute data elements used in these simulation models.

The concepts of vegetation classification and mapping, as well as the general relationships between them, are well described in Existing Vegetation Classification and

Mapping Technical Guide (Brohman and Bryant 2005). This project documentation

describes the Northern Region’s procedures used in R1-VMP for classification and

mapping of existing vegetation, and identifies the mechanism for integrating these

classifications and maps with inventory data collected through the Forest Inventory and

Analysis (FIA) program. This document also specifically describes the classification

logic, mapping methods, and inventory compilation strategies used in R1-VMP. 

3.0 Vegetation Classification

A comprehensive discussion of the nature, purposes, and principles of the classification

of natural phenomena was included in John Stuart Mill’s System of Logic (1st ed., 1846),

a treatise on inductive logic as the basis of the scientific method. Classification is a fundamental activity of science and an integral part of assimilating and organizing information

to produce knowledge (Mill 1846; Buol et.al. 1980; Gauch 1982). 

Figure 3. Relationships of vegetation classification, mapping, and inventory.
Existing Vegetation Classification & Mapping Technical Guide 3C-33

Classification is the process of grouping of similar entities into named types or

classes based on selected shared characteristics. Classification is a form of inductive

reasoning that “establishes general truths from a myriad of individual instances”

(Trewartha 1968). Classification is a fundamental activity of science and an integral

part of human thought and communication (Gauch 1982). It is how we assimilate and

organize information to produce knowledge. “When we have a definition for anything,

when we really have studied its nature to the point where we can say that it is “this” and

not “that,” we have achieved knowledge” (Gerstner 1980 as cited in Boice 1998). Even

if classification categories are conceptual or abstract rather than absolute facts, they still

serve to formulate general truths based on numerous observations.

A class is “a group of individuals or other units similar in selected properties and

distinguished from all other classes of the same population by differences in these properties” (Buol et al. 1980). The properties selected as the basis for grouping individuals

into classes are called differentiating characteristics (Buol et al. 1980). There are two

fundamental approaches to selecting differentiating characteristics; they produce two

different kinds of classes (Mill 1846) and two different kinds of classifications (Buol et

al. 1980; Pfister and Arno 1980; USDA 1993).

A natural or scientific classification is a classification in which the differentiating

criteria are selected in order to “bring out relationships of the most important properties

of the population being classified, without reference to any single specified and applied

objective” (Buol et al. 1980). In developing a scientific classification, “all the attributes

of a population are considered and those which have the greatest number of covariant or

associated characteristics are selected as the ones to define and separate the various

classes” (Buol et al. 1980). A set of classes developed through scientific classification is

referred to as taxonomy (USDA 1993). A taxonomic unit (or taxon) is a class developed

through the scientific classification process, or a class that is part of taxonomy.

A technical classification (or technical grouping) is a classification in which the differentiating characteristics are selected “for a specific, applied, practical purpose” (Buol et al.

1980, Pfister and Arno 1980). The resulting classes are called technical groups. In contrast

to natural classifications, technical classifications are based on one or a few properties to

meet a specific interpretive need, instead of considering all the properties of the population. 

Vegetation classification consists of grouping a potentially infinite number of stands

or plots into relatively few vegetation types. A vegetation type is a named class of plant

community or vegetation defined on the basis of selected shared floristic and/or physiognomic characteristics, which distinguish it from other classes of plant communities

or vegetation. Vegetation types are taxonomic units developed through the scientific

classification process as described above. Scientific classification makes meaningful

generalizations about each vegetation type possible, thus reducing complexity and furthering

communication while maintaining meaningful differences among types (Pfister and Arno
3C-34 Existing Vegetation Classification & Mapping Technical Guide

1980). Members of a vegetation type (e.g., plots or stands) should be more similar to

each other than they are to members of other vegetation types. Structural classifications,

such as those based on canopy cover, are technical groups developed through a technical

classification process. Technical groups also generalize all possible conditions into

classes that are more similar to members of the same class than to members of other

classes and provide the basis for analysis applications and interpretations related to the

“applied, practical purpose” of the classification.

Following the classification principles described above as well as the mid-level

classification standards included in the Existing Vegetation Classification and Mapping

Technical Guide (Brohman and Bryant 2005), the Northern Region Vegetation Council

developed and adopted the following vegetation and landcover classifications.

3.1 Physiognomic and Floristic Classification

Physiognomic and floristic composition are the most fundamental components of a

vegetation map. The National Vegetation Classification (NVC) (FGDC 1997) has defined

a hierarchical system for arranging these components into taxonomic units, which is the

foundation for the map hierarchy described in the technical guide. When the NVC was

adopted as an FGDC standard in 1997 the document provided the description of both the

physiognomic and floristic composition components. Two floristic levels, alliances and

associations, were defined. Standards were provided for only the physiognomic portion

of the hierarchy. To further develop standards for the NVC, the Ecological Society of

America (ESA), through a memorandum of understanding with the FGDC, established a

vegetation classification panel. In May 2002 the ESA vegetation panel submitted Standards

for Associations and Alliances of the U.S. National Vegetation Classification (Jennings

et al. 2004). The ESA document states as follows: “Consistent with FGDC principles, the

standards here for floristic units relate to vegetation classification and are not standards

for the identification of mapping units. Nevertheless, types defined using these standards

can be mapped and can be used to design useful map units subject to the limitations of

scale and mapping technology.” The ESA proposed standards for associations and

alliances along with the physiognomic standards in the 1997 U.S. National Vegetation

Classification form the basis for the mapping standards identified in the technical guide.

It is assumed that all map units will fit somewhere within this hierarchy, whether or not

they are included in the FGDC classification.

Landscape features dominated by land uses (e.g., urban areas) and water bodies are

to be mapped as non-vegetative if they are less than the minimum standard for vegetative

cover. Mapping continuous areas requires using land use and cover as well as vegetation

classification systems. While many areas of the National Forests could be mapped using

map units defined by vegetation physiognomic classification only, sparsely vegetated
and non-vegetated areas mapped solely as such, give little information to the map user.

Water was explicitly included as a life form-level land cover class and classes such as

snow, clouds, and shadows were replaced using adjacent life forms. 

Floristic map units based on vegetation types from a fully documented and adopted

existing vegetation classification system are required by the national standard; however,

few vegetation classifications that meet the FGDC exist in the Northern Region. The

near term availability of adopted FGDC vegetation classifications prompted the Vegetation

Council to develop and adopt a consistent approach to the classification and mapping of

dominance types. Dominance types have been widely used in the development of map

units where remote sensing imagery is the primary basis for map feature delineation.

“Under the dominance approach, vegetation types are classified on the basis of dominant

plant species found in the uppermost stratum. Determining dominance is relatively easy,

requiring only a modest floristic knowledge. However, because dominant species often

have a geographically and ecologically broad range, there can be substantial floristic and

ecologic variation within any one dominance type.”...“ ‘Dominance types’ provide a

simple method of classification based on the floristic dominant (or group of closely

related dominants) as assessed by some measure of importance such as biomass, density,

height, or leaf-area cover” (Kimmins 1997). They represent one of the lowest levels in

several published classification hierarchies (e.g., Cowardin et al. 1979; Brown et al.1980).

Existing Vegetation Classification & Mapping Technical Guide 3C-35

Life Form (order level of the NVCS physiognomic hierarchy)

Code Label Description

3100 GFB Grass/Forb dominated life form

3300 SHR Shrub dominated life form

4000 TRE Tree dominated life form

5000 WTR Water landcover

7000 SVG Sparsely vegetated landcover

Life Form Key

A. Tree dominated life form > 10% canopy cover ..............................................................................TRE

B. Tree dominated life form < 10% canopy cover..........................................................................Go to B

A. Shrub dominated life form > 10% canopy cover............................................................................SHR

B. Shrub dominated life form < 10% canopy cover .......................................................................Go to C

C. Grass/Forb dominated life form > 10% canopy cover....................................................................GFB

C. Grass/Forb dominated life form < 10% canopy cover ...............................................................Go to D

D. TRE+SHR+GFB+non-vascular >10% canopy cover..............................NDL [no dominant life form]

D. TRE+SHR+GFB+non-vascular <10% .......................................................................................Go to E

E. TRE+SHR+GFB+non-vascular <10% and >1% canopy cover .....................SVG [sparsely vegetated]

E. TRE+SHR+GFB+non-vascular <1% ...................................................................NVG [non-vegetated]
3C-36 Existing Vegetation Classification & Mapping Technical Guide

The dominant classification adopted for R1-VMP is based on relative canopy cover

and is exhaustive and mutually exclusive. The basic classification logic is illustrated in

the following tree dominance-type key:

3.2 Tree Diameter Classification

Tree diameter class (also called overstory tree diameter class) is defined here as any of

the intervals into which a range of tree diameters may be divided for classification

(Helms 1998). In this project the mean diameter at breast height (4.5 ft /1.37 m. above

the ground) is calculated for the trees forming the upper or uppermost canopy layer

(Helms 1998). Note: this mean is calculated as the basal area weighted mean diameter. 

3.3 Tree Canopy Cover Classification

Tree canopy cover (also called tree canopy closure) is defined here as the total nonoverlapping tree canopy in a delineated area as seen from above. (Tree canopy cover is

not defined by a hemispherical projection as seen from below.) Tree canopy cover below

10% is considered a nontree polygon. The tree canopy cover breaks are consistent with

the physiognomic class breaks for vegetation. 

Tree Dominance-Type Key

A. Single most abundant species ≥ 60% of total canopy cover.....................................List single species

A. Single most abundant species ≤ 60% of total canopy cover ......................................................Go to B

B. 2 most abundant species ≥ 80% of total canopy cover and each species individually is

≥ 20% of total canopy cover ........................................................List 2 species, in order of abundance

B. 2 most abundant species ≤ 80% of total canopy cover...............................................................Go to C

C. 3 most abundant species ≥ 80% of total canopy cover and each species individually is

≥ 20% of total canopy cover ........................................................List 3 species, in order of abundance

C. 3 most abundant species ≤ 80% of total canopy cover ..............................................................Go to D

D. Shade intolerant species total CC ≥ shade tolerant species total CC............................................IMXS

D. Shade intolerant species total CC ≤ shade tolerant species total CC..........................................Go to E

E. GF+C+WH canopy cover ≥ AF+S+MH canopy cover ................................................................TGCH

E. GF+C+WH canopy cover ≤ AF+S+MH canopy cover..................................................................TASH

Tree diameter class 

Code DBH Description

1 0-4.9 Seedling/Sapling

2 5-9.9 Small tree

3 10-14.9 Medium tree

4 15-19.9 Large tree

5 20 + Very Large tree

Tree canopy cover class 

Code Cover % Description

1 10-24.9% Low

2 25-59.9% Moderate

3 60-100% High
Existing Vegetation Classification & Mapping Technical Guide 3C-37

4.0 Map Design

Map design involves two fundamental processes. The first, map unit design, identifies the

vegetation characteristics to be mapped and assembles or develops classification keys for

each of the map attributes used to describe those characteristics. This process establishes

the relationship between vegetation classification and mapping. The second process, map

feature design, identifies the spatial characteristics and structure of the map.

A vegetation map unit is a collection of areas identically defined and named in

terms of their component taxonomic units and/or technical groups (adapted from USDA,

Soil Survey Division 1993). These vegetation map units can be based on the taxonomic

units and technical groups of physiognomic, floristic, or structural classifications, or on

combinations of these. Map units are designed to provide information and interpretations

to support resource management decisions and activities. The map unit design process

establishes the criteria for aggregating or differentiating vegetation taxonomic units and

technical groups to create corresponding map units. Therefore, a mapping unit is comprised of one or more taxonomic units and/or technical groups from one or more specific

classifications. The criteria used to aggregate or differentiate within physiognomic types,

vegetation types, or structural classes to form mapping units will depend on the purpose

of, and the resources devoted to, any particular mapping project (Jennings et al. 2004).

For example, map units designed to provide information on existing forest structure to

characterize wildlife habitat or fuel condition would be based on a combination of tree

canopy cover technical groups and tree diameter technical groups. The map unit design

process is more complex for floristic classifications than for relatively simple structural

classifications. The mapping standards for vegetation cover, tree canopy closure, and

tree diameter described in this section represent general-purpose map unit designs for

each structural classification at all map levels, although local information needs may

occasionally require exceeding the standards. 

Map units depicted on maps within individual areas or delineations that are nonoverlapping and geographically unique are referred to as map features (e.g., polygon

delineations or region delineations). The map feature delineation process should be based

on the map units identified in the map unit design process. Typically, one map unit is

repeated across the landscape in many individual map feature delineations. 

The design process for the primary R1-VMP map products is described in the

following sections.

4.1 Physiognomic and Floristic Map Design

The dominance type classification described in section 3.1 was aggregated and generalized

using the following logic to identify the map units used in R1-VMP. The variable minimum

map feature standard used for life form applied to dominance types.
3C-38 Existing Vegetation Classification & Mapping Technical Guide

The dominance type map unit design process described in this section produced

slightly different sets of map units for each model, reflecting the ecological differences

in these models (see Appendix A). Combining the map units for each model resulted in

36 unique dominance types. An objective evaluation of the map accuracy of R1-VMP

dominance types illustrated the nature and magnitude of map error associated with this

large set of map units and suggested logical aggregations of map units to achieve reasonable accuracy for the regional product. It is important to recognize that the structure

of the error varied by dominance type and between models. Therefore, forest or planning

zones may aggregate dominance types differently depending on the intended analysis

application and the geographic extent of the analysis area (see ssection 5.10). 

4.2 Tree Diameter Map Design

To reduce error to acceptable levels, the tree diameter classification described in Section

3.2 was aggregated and generalized to the following three classes for R1-VMP. The variable

minimum map feature standard used for life form applied to tree diameter classes.

DOMINANCE TYPE 1—ELEMENTAL CLASSIFICATION [DOM1]

Classification Rule Set: 

1-species > 60% tot BA that species

2-species > 80% tot BA those 2-species—listed in order of abundance

3-species > 80% tot BA those 3-species—listed in order of abundance

Shade intol. > Shade tol. IMXS [intolerant mixed spp]

Shade tol. > shade intol.

G, WRC, WH > AF, ES, MH TGCH

G, WRC, WH < AF, ES, MH TASH

Results in over 850 different types

DOMINANCE TYPE 4—SPECIES GROUPS [DOM4]

Classification Rule Set: 

1-Species: Same as DOM1

2-Species: All 2-species DOM1 types with the same most abundant species are grouped into SPPP1MIX (e.g., ABGR-PSME, ABGR-PICO, etc = ABGR-1MIX)

3-Species: All 3-species types with the same most abundant species (from DOM1) are grouped into 

SPPP-2MIX e.g., ABGR-PSME-PICO, ABGR-PICO-LAOC, etc = (ABGR-2MIX)

IMXS, TASH, TGCH: Same as DOM1

Results in over 42 different types

DOMINANCE TYPE 4—SPECIES GROUPS [DOM4]

Map Unit Design 

A frequency distribution of DOM4 types is made from FIA PSU data. 

If either the single-species or the single-species-1MIX are less than 1% of the total number of forested

FIA PSUs, they are collapsed into a single species. 
Existing Vegetation Classification & Mapping Technical Guide 3C-39

4.3 Tree Canopy Cover Map Design

The tree canopy cover classes described in section 3.3 were adopted and mapped as

classified. The variable minimum map feature standard used for life form applied to tree

canopy cover classes.

4.4 Minimum Map Feature

Minimum map feature is the term used to describe the smallest size polygon required

in a map. A homogeneous area must be delineated in a map if it is equal to or greater in

areal extent than the minimum map feature standard for each map level. Stated another

way, no differing condition, greater in area than the minimum map feature as defined by

the map unit design can be left as an unmapped inclusion in a larger polygon. 

The life form and landcover classes described in section 3.1 were adopted and mapped

as classified. A variable minimum map feature standard was implemented as follows:

The dominance type map units, tree canopy cover map units, and tree diameter map

units, described in sections 4.1 through 4.3 respectively, nest hierarchically under life

form and follow the same minimum map feature standard. 

5.0 Vegetation Mapping

Vegetation mapping is the process of delineating the geographic distribution, extent, and

landscape patterns of vegetation types and/or structural characterisitcs. Satellite-based

remote sensing classifications (mainly using LANDSAT-TM data) with their associated

GIS coverages or grids and attribute databases have increasingly been used for large

area, low-cost vegetation and landcover mapping (Lachowski et al. 1996; Redmond et

al. 1996; Johnston et al. 1997; Cohen et al. 1998; Mickelson et al. 1998; Stoms et al.

1998). These satellite-based classifications are gradually replacing aerial photography as

Tree diameter map units 

Code DBH Description

1 0–4.9 Seedling/sapling

23 5–14.9 Small/medium tree

45 15–20 + Large/very large tree

Life form minimum map feature

Code Label Minimum Map Feature

3100 GFB 2.5 Acres

3300 SHR 2.5 Acres

4000 TRE 5.0 Acres

5000 WTR 1.0 Acre

7000 SVG 5.0 Acres
3C-40 Existing Vegetation Classification & Mapping Technical Guide

the primary image data for vegetation mapping. Wynne and Carter (1997) compare

characteristics of satellite remote sensing data and aerial photography relative to these

mapping applications:

• Satellite images are digital; they provide direct and cost effective GIS coverages and

databases. The spatially accurate conversion of aerial photo delineations to digital

coverage is expensive and time consuming.

• Digital images are easy to send over computer networks; they can be delivered within

hours of acquisition.

• Given a specified resolution, satellite images typically provide greater coverage than

aerial photography.

• Satellite images often have better geometric fidelity than aerial photos because of

their altitude and stability of orbits.

• Some space-borne sensors include wavelengths band, such as mid-infrared, and

thermal infrared, that cannot be detected by film.

• Repeat coverage is easily obtained; it is easily coregistered and used for applications

such as change detection and monitoring.

The USDA Forest Service national direction contained in the “Existing Vegetation

Mapping Protocol” (Brewer et al. 2003) in the Existing Vegetation Classification and

Mapping Technical Guide (Brohman and Bryant 2003) reflects the trend toward the use

of satellite remote sensing classification for vegetation mapping. R1-VMP represents the

current implementation of this national direction in the Northern Region. The following

sections, exerted and expanded from Brewer and others (2003), describe the analytical

logic and general methodology utilized in the mapping process. 

5.1 Acquisition and Preprocessing of Image and Ancillary Data

Landsat TM imagery was chosen for this work because the near-infrared and mid-infrared

reflectance of vegetation is strongly related to important vegetation canopy characteristics.

Additionally, the high spectral resolution of Landsat TM imagery was preferred above the

high spatial resolution of other sensors, such as SPOT and Landsat TM data are acquired

continuously and archived data could, therefore, be purchased to meet the time and area

needs. Landsat TM data can also be purchased as “floating scene” or “path-level” formats

providing of up to three TM scenes as a single field of view, thereby reducing the image

handling and preprocessing requirements, as well as costs.

A good seasonal image data acquisition window for forest vegetation opens slightly

after the date at which the vegetation is fully mature and closes just prior to its senescence. Similarly, a good data acquisition window for exploiting meaningful phenological

differences in forest vegetation opens slightly after senescence and ends with snowfall.

The consideration of an acquisition window instead of an acquisition date provides
Existing Vegetation Classification & Mapping Technical Guide 3C-41

greater operational flexibility (to minimize cloud cover or other atmospheric interference),

because it permits the date to be chosen based on a satellite overpass. In this case, the

“peak green” and “fall” image data were obtained from the EROS Data Center with the

following acquisition dates and according to the following parameters: 

Cell Sizes: 30m reflective, 15m panchromatic, 60m thermal (both high and low)

Orientation: Path

Datum: WGS 84

Projection: Space Oblique Mercator

File Format: FSTL7

Path 41 Image Acquisition Dates: 10 July 2002; 14 October 2002

Path 42 Image Acquisition Dates: 18 August 2002; 6 November 2002

Path 43 Image Acquisition Dates: 6 August 2002; 12 October 2002

All images were ortho-rectified to previously terrain-corrected images for the

respective paths using the Geometric Correction Module and the Landsat orbit model in

ERDAS IMAGINE (ERDAS 1997) as well as 7.5-minute digital elevation models.

Between 200 and 300 ground-control points (GCP) throughout each of the unrectified

images were used in the ortho-rectification process. The rectification involved the Cubic

Convolution algorithm with a resulting Root Mean Square (RMS) error was less than

one-half of a pixel, or 7.5m, 15 m, or 30m depending on the cell size. The R1-VMP

image handling steps, ortho-rectification process, and resulting datasets are documented

in appendix B. Ancillary topographic data derived from 7.5-minute digital elevation

models downloaded from the U.S. Geological Survey were assembled, co-registered, and

clipped to the same study area boundary. 

5.2 Ecogeographic Stratification 

Lillesand and Kiefer (2000) discuss the commonality of using ancillary data to perform

geographic stratification of an image dataset prior to classification. They further describe

the aim of this process as to “subdivide an image into a series of relatively homogeneous

geographic areas (strata) that are then classified separately.” The homogeneity of these

geographic areas is largely determined by the composition of biophysical environments

included in the stratification. These environment settings are important for the stratification

of this type of project because they facilitate the delineation and description of ecosystems

that behave in a similar manner and influence the natural disturbance processes that create

finer-scale patterns such as existing vegetation (Jensen et al. 1997). The USDA Forest

Service National Hierarchical Framework of Ecological Units (Bailey et al. 1994)

provided the delineations used for geographic stratification of the R1-VMP project area.
3C-42 Existing Vegetation Classification & Mapping Technical Guide

Figure 4. Section- and subsection-level delineations in the ECOMAP hierarchy.

Figure 5. Subpath data models used for ecogeographic stratification of Landsat ETM floating scenes.

As described by ECOMAP the framework is: 

a regionalization, classification, and mapping system for stratifying the Earth

into progressively smaller areas of increasingly uniform ecological potentials.

Ecological types are classified and ecological units are mapped based on

associations of those biotic factors and environmental factors that directly affect

or indirectly express energy, moisture, and nutrient gradients that regulate the

structure and function of ecosystems. These factors include climate, physiography, water, soils, air, hydrology, and potential natural communities.

The appropriate level of this hierarchy for ecogeographic stratification in this project

is the section-level delineation described by McNab and Avers (1994) and illustrated in

figure 4. These delineations were used to stratify Landsat ETM floating scene sets in

ERDAS Imagine software (ERDAS 1997). This geographic stratification results in 12

sub-path data models (Figure 5) rather than eight Landsat TM scene models. This stratification improves model performance by limiting the variance associated with vegetation

types, and increases the utility of reference data. 

Prairie

Idaho batholith

Bitterroot Valley

Blue Mountains

Okanogan Highlands

Flathead

Northern Rockies

Bitterroot Mountains

Subsection Boundaries

(a) (b) (c)
Existing Vegetation Classification & Mapping Technical Guide 3C-43

The 12 subpath data models were subsequently modified (Figure 6) to reduce file size and

eliminate redundancy. The portion of model 13 not included in model 8 was appended to

model 11. Similarly, the portion of model 10 not included in model 5 was appended to

model 9. Models 7 and 12 were both carried through the classification process to provide

flexibility in eliminating smoke and haze problems present in the image data. 

5.3 Image Segmentation

As stated in Ryerd and Woodcock (1996), ”image segmentation is the process of dividing

digital images into spatially cohesive units, or regions. These regions represent discrete

objects or areas in the image.” This segmentation and merging process is influenced by

the variance structure of the image data and provides the modeling units that reflect lifeform composition, stocking, tree crown size differences, and other vegetation and/or

landcover characteristics (Haralick and Shapiro 1985; Ryerd and Woodcock 1996).

Segmentation and merging of Landsat ETM satellite imagery in R1-VMP utilized the

segmentation functionality within the software eCognition (Baatz et al. 2001). The segmentation process in eCognition is based on both the local variance structure within the

imagery and shape indices. This segmentation process produces image objects that serve

as the base classification units within the object-oriented classification programs. These

image objects effectively depict the elements of vegetation and landcover pattern on the

landscape (McDonald et al. 2002). Figure 7 illustrates the image segmentation-based

depiction of landscape pattern displayed over aerial digital imagery. Given the R1-VMP

project objective of mapping vegetation and landcover pattern, the criteria for spatially

differentiating map features was based on structural, floristic, and physiognomic characteristics of the vegetation to be mapped, as well as nonvegetated landscape elements.

Within the context of R1-VMP, the delineation of map features depicting the vegetation

Figure 6. Modified subpath data models used for ecogeographic stratification of Landsat ETM

floating scenes.

(a) (b) (c)
3C-44 Existing Vegetation Classification & Mapping Technical Guide

configuration across the landscape representing elements of vegetation pattern is synonymous

with landscape patch delineation. The term “patch,” as defined in a glossary of common

terms included in Land Mosaics: The Ecology of Landscapes and Regions (Forman 1995),

is “a relatively homogenous nonlinear area that differs from its surroundings.” This definition is consistent with other common reference texts including Picket and White (1985)

and Forman and Godron (1986). It is also consistent with the common use of the term in

the landscape ecology literature (Hartgerink and Buzzaz 1984; Scheiner 1992). The term

patch can be refer areas of forest, nonforest vegetation, rock/barren environment, or water.

In contrast, the term “stand” has long been used to refer to the basic unit of forest management (Toumey 1937). It also has been used as the basic unit of mapping and inventory

(Graves 1913). A “stand” is defined as “a community, particularly of trees, possessing

sufficient uniformity as regards composition, age, spatial arrangement, or condition, to

be distinguishable from adjacent communities, so forming a silvicultural or management

entity.” This definition of a stand from the Society of American Forester’s Terminology of

Forest Science, Technology, Practice, and Products (Ford-Robertson 1971) is consistent

with definitions from a variety of reference texts, including Toumey (1937), Smith (1986),

and Oliver and Larson (1990), as well as A Dictionary of Ecology, Evolution, and

Systematics (Lincoln et al. 1982) and the definition provided in the USDA Forest Service

Timber Management Handbook (FSH 2709). Historically, most vegetation mapping

completed by the agency has been conducted through delineation of forest stands. The

terms “patch” and “stand” may be synonymous depending on the degree to which management considerations are incorporated into stand delineations along with compositional

and structural characteristics. It is important to recognize, however, that many past stand

delineations contain multiple vegetation conditions and map units, and are multiple map

Figure 7. Image segmentation of Landsat ETM data.
Existing Vegetation Classification & Mapping Technical Guide 3C-45

features in the R1-VMP mapping effort. The image objects delineated through the R1-VMP

image segmentation process and modeled in eCognition readily aggregate thematically

and comprise vegetation and landcover patches that represent the various map units in

the hierarchy. 

5.4 Change Detection 

Change detection methodologies using digital data have been used extensively for a wide

variety of analysis applications including: fire impact studies (Parra et al. 1996), land

cover change in wetland areas (Hashem et al. 1996; Mahlke 1996), air pollution damage

detection (Hogda et al. 1995; Solheim et al. 1995), and forest-canopy change (Coppin

and Bauer 1994, 1995). Within the context of the vegetation mapping objectives R1-VMP,

the change detection method is designed to exploit phenological differences in vegetation

types (i.e., deciduous tree or shrub species dominance types or senescent grasses and

forb species dominance types).

The R1-VMP change detection procedure, like most digital change detection procedures,

must assess differences between multitemporal datasets and also separate changes of

interest from those that are irrelevant to the mapping objectives. The maximization of the

signal-to-noise ratio and the extraction of relevant multispectral features related to the

biophysical characteristics of vegetation canopies are essential to identification of meaningful phenological differences (Ngai and Curlander 1994). Coppin and others (2001) note

that preprocessing of satellite images prior to actual change detection is a critical step.

They identify the goals of preprocessing as “the establishment of a more direct linkage

between the data and biophysical phenomena (calibration), the removal of data acquisition

errors and image noise, and the masking of contaminated and/or irrelevant scene fragments.”

The synopsis of procedures and their requirements for digital change detection presented

by Coppin and Bauer (1996) comprise the basis of R1-VMP preprocessing.

Following preprocessing, single-band radiometric responses are often transformed

to strengthen the relationship between spectral data and biophysical characteristics of

vegetation canopy. Coppin and others (2001) demonstrated that a solid biophysical link

is found between forest canopy features and the Kauth-Thomas transform, a particular

case of a principal components analysis. The three main components of Kauth-Thomas

variability are termed brightness, greenness, and wetness and are the result of a GramSchmidt orthogonalization process (Kauth and Thomas 1976). Changes in these three

components constitute the basis of the R1-VMP analytical logic to exploit phonological

differences in vegetation types (Figure 8). 
3C-46 Existing Vegetation Classification & Mapping Technical Guide

5.5 Ecological Modeling and Other Ancillary Data

Ecological modeling and other ancillary data are used extensively by R1-VMP to improve

classification results. These ecological modeling approaches are incorporated into the

multisource system through knowledge-based classification and reference data stratification

within the object-oriented image analysis software, eCognition (Baatz et al. 2001). This

process facilitates the use of additional data such as potential vegetation settings, subsection-level ecological units, topography, and image illumination strata for grouping or

splitting classes to improve classification accuracy (Cibula and Nyquist 1987; Bolstad

and Lillesand 1992; Cohen and Spies 1992; Brown et al. 1993; Coppin and Bauer 1994;

Goodchild 1994).

One of the primary ecological modeling approaches used in R1-VMP incorporates

data on potential natural vegetation (PNV). PNV is “the vegetation...that would become

established if all successional sequences were completed without interference by man

under the present climatic and edaphic conditions....” (adapted from Tuxen 1956 as cited

in Mueller-Dombois and Ellenberg 1974). PNV classifications are based on existing

vegetation, successional relationships, and environmental factors (e.g., climate, geology,

soil, etc.) considered together. The PNV classifications within the R1-VMP project area

include Forest Habitat Types of Montana (Pfister et al. 1977); Forest Habitat Types of

Northern Idaho: A Second Approximation (Cooper et al. 1991); and Grassland and

Shrubland Habitat Types of Western Montana (Mueggler and Stewart 1980). The PNV

types and their associated biophysical settings have strong relationships with existing

vegetation and therefore provide useful information in the image-classification process.

The habitat types from these classifications were aggregated to 38 types and mapped by

Jones and others (1998, 2002). R1-VMP further aggregated the 38 types to 10 types to

facilitate the classification process.

Figure 8. Changes in K-T greenness from multidate imagery. (a) July date; (b) October date; (c)

degree of change between dates.

High

Low

(a) (b) (c)
Existing Vegetation Classification & Mapping Technical Guide 3C-47

5.6 Reference Data

In remote sensing projects, reference data serve two main purposes. First, reference data

establish a link between variation on the ground and in the image. This link is necessary

for assigning image-modeling units (pixels or regions) to discrete land-cover classes in the

image classification process. Second, reference data help assess the accuracy of a map.

Figure 9. Illumination strata. (a) Hillshade created from digital

elevation model; (b) Illumination classes of surface for both dates

of imagery.

Figure 10. Fire-severity data. (a) Post-fire image with

fire scar and burn perimeter; (b) Fire-severity classes

generated through a change detection process.

In addition to PNV, R1-VMP incorporated two other biophysical variables: (1) two

indices of insolation derived from combinations of slope and aspect generated from 30 meter

DEM data, and (2) subsection-level delineations further subdividing the ecogeographic

stratification described above and illustrated in figure 4 (McNab and Avers 1994). 

R1-VMP also stratified the image data by the illumination at the time of image

acquisition. This process results in three strata: (1) illuminated in both the “summer”

and “fall” images; (2) nonilluminated in both the “summer” and “fall” images; and (3)

illuminated in “summer” but nonilluminated in “fall.” These strata improve the spectral

relationships between vegetation types and reflectance values (Figure 9). 

Additional ancillary information is provided by fire-severity data classifying recently

burned areas (Figure 10). These data were operationally produced by the USDA Forest

Service (Gmelin and Brewer 2002) following major fire events in 2000 and 2001, and

are used to characterize first-order fire effects on vegetation. They are generated from a

Normalized Difference Burn Ratio (NBR) analytical approach, following Key and

Benson (1999) as adapted by Brewer and others (2003).

(a)

(a)

(b) (b) Not Illuminated

Illuminated

Both

Unburned

Grass/Shrub

Low

Moderate

High
3C-48 Existing Vegetation Classification & Mapping Technical Guide

The most common sources of reference data for remote sensing projects are aerial

photo interpretation and field data collection. It is quite common for remote sensing

projects to use photo interpretation as a primary source of reference data or to combine

these two sources. Numerous works illustrate the development and use of reference data

(Strahler 1980; Shasby and Carneggie 1986; Cibula and Nyquist 1987; Fung and LeDrew

1987; Chuvieco and Congalton 1988; Leprieur and Durand 1988; Franklin and Peddle

1990; Janssen et al. 1990; Marceau et al. 1990; Cetin and Levandowski 1991; Loveland

et al. 1991; Peddle and Franklin 1991; Bolstad and Lillesand 1992; Foody et al. 1992;

Gong and Howarth 1992; Gong et al. 1992; Bauer et al. 1994; Coppin and Bauer 1994;

Green et al. 1994; Woodcock et al. 1994; Cohen et al. 1995’ Dikshit and Roy 1996;

Shandley et al. 1996; Jakubauskas 1997; Johnston et al. 1997; Cross et al. 1988; Deppe

1998; and Lo and Watson 1998). Many of these studies used photo interpretation in

conjunction with field sampling, while others relied exclusively on the photo interpretation

to provide these reference data. Independent of the source of reference data, it is important

to promote consistency between training and accuracy-assessment data. These sets should

be of similar type and follow the taxonomic logic and data standards. For most projects,

the same type of data is collected for training and accuracy-assessment applications.

In R1-VMP, training and accuracy-assessment data are generated through a structured

aerial photo interpretation process (Appendix C) that integrates a variety of field sampled

inventory datasets (Appendix D). Our experience suggests that an aerial perspective is often

useful for remote sensing training data acquisition and that skilled interpreters can add

local knowledge and experience to the classification process. Additionally, resource aerial

photography remains the most commonly available remote sensing data source; however,

we integrate high-resolution, multispectral data with resource photography where available.

This structured photo interpretation process provides an explicit mechanism for

integrating existing field sample data from a variety of sources, both within the USDA

Forest Service and from cooperating entities. Existing field data is screened to ensure

data quality and currency using a standardized process. This provides the opportunity to

benefit from the agency’s substantial investment in field data while screening out data

rendered unusable by management activities, disturbance agents, and/or time since collection. Through this process the image interpreter is able to “fit” field data and other

ancillary data to the segmented imagery. This process accomplishes the same objective

described by Robinson and Tilton (1991), but fits the training data to the segmentation

rather than fitting the segmentation to the training data.

Common image interpretation techniques are used to characterize elements of vegetation pattern that comprise life form, dominance type, tree size class, and tree canopy

cover (Avery 1977, Campbell 1987, Lillesand and Kiefer 1987, Lachowski et al. 1996).

The variables collected include: life form/land-use class cover percent and connectivity;

dominance type cover percent and connectivity; tree size class cover percent; tree canopy

cover percent and connectivity, and total vegetation canopy cover percent (Figure 11).
Existing Vegetation Classification & Mapping Technical Guide 3C-49

Field-sampled tree, vegetation composition, and ground-cover composition data

were collected on a subset of a randomly selected set of region-polygons as a means to

validate the photo interpretation reference data collection. Data were collected following

Forest Service common stand exam (CSE) protocols and data was loaded into Field

Sampled Vegetation (FSVeg) database. A comparison of the field-sampled data and the

photo-interpreted data for tree dominance type, tree sizeclass and tree canopy cover is

found in appendix E. 

5.7 Hierarchical Classification

The Federal Geographic Data Committee (FGDC) Vegetation Classification Standards

(1997) establishes a hierarchical existing vegetation classification with nine levels. The

top seven levels are primarily based on physiognomy. The two lowest levels, alliance and

association, are based on floristic attributes. The USDA Forest Service recently released

the national direction for classification and mapping of existing vegetation to implement

the FGDC standards and to provide direction for classifying and mapping structural

characteristics (Brohman and Bryant 2005). This direction applies to a variety of

geographic extents and thematic resolutions characterized as map levels. The Northern

Region Vegetation Mapping Project is specifically designed to meet this national program

direction at the mid-level.

Through the classification functionality of eCognition, a nested hierarchical classification scheme is applied that uses membership functions derived from knowledge bases

for the physiognomic and structural classifications and fuzzy-set classifiers based on

reference data and nearest neighbor algorithms for the floristic (dominance type) classification. This design provides a consistent linkage between the floristic and structural

classifications commonly used by the agency at the mid-level and the physiognomic

classifications used at the broad-level and national-level and required by the FGDC

vegetation classification standards (Brohman and Bryant 2005).

Figure 11. Stereoscope used in the reference data collection process.
3C-50 Existing Vegetation Classification & Mapping Technical Guide

Implementation of this classification hierarchy produces

separate GIS coverages, grids and associated geospatial

databases for four primary attributes. These attributes

include: life form, dominance type, tree canopy cover,

and tree size class. The hypothetical dominance type,

tree size class, and tree canopy cover map products included in figure 12 illustrate the

relationships of these attributes to the original image objects. These original image objects

were merged following the minimum map feature standards from section 4.4. The merged

image objects were then used to produce the GIS coverages and grids for the four primary

map products. The original image objects with the four primary attributes could be

obtained for analysis applications requiring different minimum map feature standards

and/or different attribute combinations than those available from the R1-VMP deliverable

map products. For information and assistance contact Northern Region, Engineering Staff;

Geospatial Group. No coverage and grid combining the four attributes was produced

through R1-VMP. The analytical logic used to combine these attributes should be based

on intended analysis objectives. Any combination of these four primary map products

could be produced to meet specific analysis objectives, with the logic of the combination

defined by the end user. It is expected that a combined coverage and grid will be required

to meet a variety of general analysis objectives and business needs. The specific process

and logic used to produce this combined product will be defined by the Northern Region

Vegetation Council and released as a map product following its completion. 

Figure 12. Hypothetical classification attributes (map units) and

image objects.

Figure 13. Sub-path data model mosaic used for primary map

products.

Grass/Forb

Douglas Fir

Western Larch

Ponderosa Pine

Grass/Forb

Seeding/Sapling

Medium Tree

Large Tree

Grass/Forb

High Tree Canopy Cover

Low Tree Canopy Cover

(a)

(c) (d)

(b)
Existing Vegetation Classification & Mapping Technical Guide 3C-51

5.8 Mosaic Subpath Data Models

The sub-path data models described in section 5.2 and processed as described in sections

5.3 through 5.7 were clipped and merged to create continuous GIS coverages and grids for

the four primary map products. The clip and merge process created non-overlapping model

boundaries (Figure 13) within the overlap zones form the original sub-path data models.

5.9 Accuracy Assessment

Accuracy assessments are essential parts of all remote sensing projects. First, they provide

the basis to compare different methods and/or sensors. Secondly, they provide information

regarding the reliability and usefulness of remote sensing techniques for a particular

application. Finally, and most importantly, accuracy assessments support the spatial data

used in decision-making processes. Too often vegetation and other maps are used without

a clear understanding of their reliability. A false sense of security about the accuracy

of the map may result in an inappropriate use of the map and important management

decisions may be made on data with unknown and/or unreliable accuracy. Although

quantitative accuracy assessment can be time-consuming and expensive, it must be an

integral part of any vegetation-mapping project.

Accuracy, however, is not a state variable. It is very important to evaluate the results

of any accuracy assessment in the context of the intended analysis application and the

management decision the data and analyses are intended to support. This evaluation needs

to balance the desired level of precision (i.e., the level of thematic detail) with the desired

level of accuracy. For many analyses, detailed thematic classes are aggregated to produce

fewer, less detailed and more accurate classes. It is appropriate in these instances to assess

the accuracy of the aggregated classes rather than characterize the aggregations with the

detailed assessment. It may even be appropriate to aggregate some classes based on the

structure of the error, provided that the aggregations meet the analysis objectives. It is also

important to determine the level of uncertainty that is acceptable to support a particular

management decision. Many management decisions are based on the relative ranking of

alternatives rather than the absolute differences. Conversely, some simulation modeling

applications are better served by more precise (thematically detailed) data than by more

accurate generalized data. These modeling applications are often used to establish longterm vegetation pattern and process relationships. These models generally perform better

with a more detailed representation of vegetation patterns. 

The dominance type map unit design process described in section 4.1 produced

slightly different sets of map units for each model reflecting the ecological differences in

these models. Combining the map units for each model resulted in 36 unique dominance

types. An objective evaluation of the map accuracy of R1-VMP dominance types illustrated the nature and magnitude of map error associated with this large set of map units

and suggested logical aggregations of map units to achieve reasonable accuracy for the
3C-52 Existing Vegetation Classification & Mapping Technical Guide

regional product. The R1-VMP dominance type map product represents a general-purpose

aggregation from 36 to 16 types that are suitable for most analysis applications. It is

important to recognize, however, that the structure of the error varied by dominance type

and between models. Therefore, forests and/or planning zones may aggregate dominance

types differently depending on the intended analysis application and the geographic extent

of the analysis area. The hierarchical classification logic used in R1-VMP allows for a

relatively simple aggregation of types and recalculation of accuracy for analysis objectives

that are not well served by the general-purpose product provided. The accuracy assessment

documentation for the R1-VMP dominance type map product is included in appendix E. 

Quantitative accuracy assessment depends on the collection of reference data.

Reference data is known information of high accuracy (theoretically 100% accuracy) about

a specific area on the ground (the accuracy assessment site). The assumed-true reference

data can be obtained from ground visits, photo interpretations, video interpretations, or

some combination of these methods. R1-VMP used the reference data process described

in section 5.6 with a random sample design following Czaplewski (1999). R1-VMP

training and accuracy assessment data are generated through a structured aerial photo

interpretation process that integrates a variety of field sampled inventory datasets. Our

experience suggests that an aerial perspective is often useful for remote sensing training

data acquisition and that skilled interpreters can add local knowledge and experience to

the accuracy assessment process. Additionally, collecting enough field observations is so

prohibitively expensive that valid map evaluation cannot be conducted. R1-VMP followed

a random selection process for accuracy assessment regions. However, the photo interpretation process was limited to areas with

resource aerial photography coverage. The

accuracy assessment locations are illustrated in figure 14. 

In a map accuracy assessment sites

are generally the same type of modeling

unit used to create the map (image

objects as well as image objects merged

to a specified minimum map feature in

R1-VMP map products). Accuracy

assessment involves the comparison of

the categorized data for these sites (i.e.,

image objects and merged objects) to the

reference data for the same sites. The error

matrix is the standard way of presenting

results of an accuracy assessment (Story

and Congalton 1986). It is a square array

Figure 14. Accuracy assessment region locations

used for primary map products.
Existing Vegetation Classification & Mapping Technical Guide 3C-53

in which accuracy assessment sites are tallied by both their classified category in the image

and their actual category according to the reference data. The following table provides a

hypothetical example error matrix to illustrate accuracy assessment concepts and relationships (actual R1-VMP error matrices are provided in Appendix E). Typically, the

rows in the matrix represent the classified image data, while the columns represent the

reference data. The major diagonal, highlighted in the following table, contains those

sites where the classified data agree with the reference data.

The nature of errors in the classified map can also be derived from the error matrix.

In the matrix, errors (the off-diagonal elements) are shown to be either errors of inclusion

(commission errors) or errors of exclusion (omission errors). Commission errors are

shown in the off-diagonal matrix cells that form the horizontal row for a particular class.

Omission error is represented in the off-diagonal vertical row cells. High errors of

omission/commission between two or more classes indicate confusion between these

classes (Story and Congalton 1986).

Useful measures of accuracy are easily derived from the error matrix.

• Overall accuracy, a common measure of accuracy, is computed by dividing the total

correct samples (the diagonal elements) by the total number of assessment sites

found in the bottom right cell of the matrix.

• Producer’s accuracy, which is based on omission error, is the probability of a reference

site being correctly classified. It is calculated by dividing the total number of correct

accuracy sites for a class (diagonal elements) by the total number of reference sites

for that class found in the bottom cell in each column.

• User’s accuracy, which is based on commission error, is the probability that a map

feature on the map actually represents that category on the ground. User’s accuracy

Herbaceous/

Tree Shrub nonvascular Sparsely

dominated dominated dominated vegetated Row total

Tree dominated 65 4 22 24 115

Shrub dominated 6 81 5 8 100

Classified Herbaceous/ 

data nonvascular 0 11 85 19 115

dominated

Sparsely vegetated 47 3 90 104

Column total 75 103 115 141 434

Overall Accuracy = 321/434 = 74 percent

Producer’s Accuracy User’s Accuracy 

Tree Dominated = 65/75 = 87 percent Tree Dominated = 65/115 = 57 percent

Shrub Dominated = 81/103 = 79 percent Shrub Dominated = 81/100 = 81 percent

Herb/Non-vasc. Dominated = 85/115 = 74 percent Herb/Non-vasc. Dominated = 85/115 = 74 percent

Sparsely Vegetated = 90/141 = 64 percent Sparsely Vegetated = 90/115 = 87 percent

Reference data
3C-54 Existing Vegetation Classification & Mapping Technical Guide

is calculated by dividing the number of correct accuracy sites for a category by the

total number of accuracy assessment sites, found in the right-hand cell of each row,

that were classified in that category.

Confidence intervals are a commonly reported component of statistical estimates.

They provide the user additional information regarding the reliability of the map product.

Confidence intervals are included for each of the R1-VMP accuracy assessments.

It is often useful to evaluate these measures of accuracy relative to the aerial extent

of each class. For example, when a particularly common class (e.g., 50-75% of the map

area) has either a very high or a very low accuracy it has a disproportionate effect on the

utility of the map for general analysis applications without a corresponding effect on the

accuracy assessment. Conversely, a relatively rare type (e.g., 1-2% of the map area)

regardless of its accuracy has relatively little effect on the utility of the map for general

analysis applications but has the same effect on the accuracy assessment as the common

type. For this reason, the R1-VMP accuracy assessment error matrices include proportions

of area represented by each class. 

A relatively recent innovation in accuracy assessment is the use of fuzzy sets for

accuracy assessments. Traditional accuracy assessment, as described above, suffers from

certain limitations. First, it assumes that each accuracy site can be unambiguously assigned

to a single map category (Gopal and Woodcock 1994); when in truth it may be part of

a continuum between map categories. Secondly, the traditional error matrix makes no

distinction between magnitudes of error. For example, in a traditional error matrix,

misclassifying “Ponderosa pine dominance type” as “Intolerant mixed conifer dominance

type” carries the same weight as the error of misclassifying it as “water.” Fuzzy logic is

designed to handle ambiguity and, therefore, constitutes the basis for part of the R1-VMP

accuracy assessment. Instead of assessing a site as correct/incorrect as in a traditional

assessment, an assessment using fuzzy sets can rate a site as absolutely wrong, understandable but wrong, reasonable or acceptable match, good match, or absolutely right (Gopal

and Woodcock 1994). The resulting accuracy assessment can then rate the seriousness of

errors as well as absolute correctness/incorrectness. For these reasons, the R1-VMP

accuracy assessments for life form and dominance type include fuzzy set-based error

matrices as well as the “fuzzy weights” used to convert the “straight up” error matrix.
Existing Vegetation Classification & Mapping Technical Guide 3C-55

Figure 15. USDA Forest Service, Northern Region, stand exam program status summary for

1980-2001.

6.0 Vegetation Inventory

The vegetation inventory data for most land management agencies and private companies

only partially covers their ownership, are often out of date, and are rarely compatible with

adjacent landowners. This is particularly true for federal land management agencies

such as the USDA Forest Service, Northern Region, that manage large geographic areas

for a variety of management objectives. Historically, most ground-based inventory data

have been collected using standard plot and quick plot stand exams, as defined by the

Timber Management Control Handbook (USDA Forest Service, FSH 2709). Using the

USDA Forest Service, Northern Region, as an example, Brewer and others (2002)

observed that most of these data apply almost exclusively to the suitable timber base, as

defined by the National Forest Management Act of 1976 (US Public Law 94-588 1976).

The remaining areas outside the suitable base have few stand exam data even though

many of the resource questions and issues apply to all lands. The collection of stand-based

data on part of the land base introduces an unknown bias when these data are used to

represent the whole land base. In addition, there are no specific design considerations for

the collection and storage of these data to facilitate their use by other land management

agencies or private landowners. 

Declining budgets for public land management agencies have resulted in dramatic

reductions in the amount and geographic extent of current, detailed inventory data. The

precipitous decline in standard plot and quick plot stand exams reflects budget trends for

inventory programs throughout the USDA Forest Service. Brewer and others (2002) describe

the effects of these reductions on current data and graphically depict the status of stand

exam based inventory data for the USDA Forest Service, Northern Region (Figure 15).

This graph illustrates the decline in acreage of stand exams, by year, from 1980 to 2001. 
3C-56 Existing Vegetation Classification & Mapping Technical Guide

Reductions in timber sale programs on public lands, particularly National Forests,

have had effects on the management (i.e., harvest schedules) of both industrial and nonindustrial private forests (Flowers et al. 1993). This change in harvest schedules has

affected the currency and completeness of inventory data from private forests; proprietary

data private forest landowners are reluctant to share.

Given the discontinuous and incomplete nature of most forest inventory data, as well

as the difficulty in maintaining currency and sharing with other landowners, data generated

by the Forest Inventory and Analysis (FIA) program of the USDA Forest Service provides

a viable alternative. FIA utilizes a systematic random grid of plot clusters, remeasured

periodically, to monitor the extent, condition, uses, impacts of management, and health

of forest ecosystems across all ownerships in the United States. These data provide an

unbiased sample for many inventory related questions. The Society of American Foresters

(2000) state that “FIA is the only program that monitors the extent, condition, uses, impacts

of management, and health of forest ecosystems across the United States.” They further

state... “FIA data serve as the foundation of large-scale policy studies and perform a

pivotal role in public and private forest planning.” They cite examples of regional and

sub-regional analyses that influence major economic and ecological management decisions including:

• Strategic planning efforts by wood-using industries routinely incorporate FIA data

into timber supply and timber product outputs.

• Development of criteria and indicators of forest sustainability depend on the growth

removals, and inventory data compiled by FIA (Reams et al. 1999).

• National forest carbon budgets for reporting under international agreements are

dependent on FIA data (Heath and Birdsey 1997).

• Assessment of ecological change and economic damage resulting from disasters

such as hurricanes or widespread wildfires.

Van Deusen and others (1999) suggest a current and accurate forest ecosystem

inventory is prerequisite to substantive discussion of issues like sustainability, national

forest policy, carbon sequestration, changes in growth and productivity, changes in landuse

and demographics, ecosystem health, and economic opportunities in the forest sector. 

Over the past decade concerns have been raised regarding the currency of FIA data,

historically remeasured every 6 to 18 years (Gillespie 1999). These concerns prompted

the American Forest and Paper Association (AF&PA) to convene two Blue Ribbon Panels

on FIA (AF&PA 1992, 1998). The high level of user community support and concerns

regarding currency of FIA data surfaced by these panels and subsequent Congressional

hearings resulted in legislation to implement an annualized forest inventory and monitoring

program to reduce the remeasurement interval (Czaplewski 1999). It is expected that the

annualized inventory design will result in substantial improvements in the currency of

FIA data. 
Existing Vegetation Classification & Mapping Technical Guide 3C-57

Historically, the FIA program produced area estimates of forest types in two phases

following a double sampling design (Reams and VanDeusen 1999). Phase one placed a

systematic random grid on aerial photography (normally 1:40,000 scale National Aerial

Photography Program NAPP). These points (with a minimum area of at least 1 acre or a

strip at least 250 feet wide) were then classified as forest or non-forest based on the FIA

definition of at least 10% tree canopy cover. The second phase subsampled the first

phase points in the field to confirm the classification. This process provided the forest

area estimation for the application of the field sampling of the permanent plot clusters

in the third phase. Reams and VanDeusen (1999) suggest the following three problems

associated with this historical method:

• No forest non-forest map is produced

• The photo interpretation process is time-consuming and labor intensive

• Current aerial photography is not always available

These issues become increasingly problematic with the shift to an annualized inventory

program. R1-VMP utilizes FIA data for two important processes. In the map unit design

process FIA data are classified and utilized to estimate abundance of dominance types.

These estimates are used to define the dominance types with sufficient aerial extent to

include as a map unit and to identify logical aggregation strategies for dominance types

with insufficient extents. The FIA data are also used for the development of sample-based

Map Unit Descriptions (MUDs). In this process the FIA data are spatially associated to

the R1-VMP map products and are then compiled to quantify various vegetation characteristics for each of the thematic classes in the map product (e.g., dominance types or

tree diameter classes). The map unit descriptions for the primary map products from

R1-VMP are included in appendix F. Similar MUDs could be developed for any map

products derived from R1-VMP data.

7.0 Maintaining Existing Vegetation Maps and Associated FIA Data

One key element to planning, inventory and monitoring success is the establishment of

consistent vegetation baseline information. Once established, changes to vegetation can

be determined along with cause of change. This information provides monitoring data to

analyze the effects of change in condition of wildlife habitats, late successional old growth,

forest health, mortality, growth, and standing forest volumes. Vegetation maps, when

combined with ground-based inventories information, are fundamental to meet the needs

of Forest and Rangeland Resources Planning Act (RPA), Forest Land and Resource

Management Plans, bioregional assessments, and more localized watershed and project

planning efforts. To understand vegetation changes on the landscape and its affect on
3C-58 Existing Vegetation Classification & Mapping Technical Guide

related natural resources, it is necessary to track changes as well as cause of change for

comparing to baseline inventories. Tracking imagery source and dates of baseline maps

as well as update imagery source and date are necessary metadata. Cause of change is

also important to know and aids in analysis of affected resources, such as wildlife habitat

or cumulative watershed impacts.

The goal for vegetation resource information, stated in the Existing Vegetation

Classification and Mapping Technical Guide (Brohman and Bryant 2005), is to have

vegetation maps no older than 5 years. Map areas require updates where changes to vegetation have occurred from various causes, such as wildfire, harvest, insect and disease

damage, vegetation treatments, re-growth, agriculture or other type conversions. Activity

databases, aerial detection surveys, and fire severity mapping, along with digital change

detection methods are useful in identifying where updates need to occur, as well as

determining causes of changes in vegetation cover.

This maintenance and update strategy is designed to work with the forests and other

cooperating entities to annually identify areas of changed conditions for systematic

updates of the R1-VMP data. The coordination work will occur near the end of each

field season (late-September/early-October) to facilitate both a field and office review.

These reviews, along with other feedback throughout the year, will identify the priority

areas for the next fiscal year program of work. Once the identified areas of changed

condition are updated (within the limits of budget and resources), the R1-VMP data will

be re-released annually on April 1st of each year. 

It is expected that the Remote Sensing Applications Center (RSAC) will continue its

support of the Burned Area Emergency Recovery (BAER) teams with the production of

Burned Area Reflectance Classifications (BARC). The BARC data, with local interpretation

and correction, will provide part of the basis for large fire activity updates. It is also

expected that the Cooperative Forestry and Forest Health Protection staff will continue

to provide Aerial Detection Survey (ADS) data for areas included in the current year’s

program of work. The ADS data, with local interpretation and correction, will provide

part of the basis for insect, pathogen, and climate disturbance activity updates. Systematic

digital change detection (following Coppin et al. 2001) coupled with activity records for

National Forest System lands can provide part of the basis for silvicultural activity

updates. Areas identified through theses processes can be spatially associated with the

FIA plot locations and provide information for the following year’s annualized inventory

program of work.

By design, R1-VMP had extensive local involvement and review by the Forests as

well as other cooperators. However, there will be systematic and non-systematic errors

identified once these data are used operationally. This maintenance strategy also

includes a “correction” component for addressing errors that were not identified during
Existing Vegetation Classification & Mapping Technical Guide 3C-59

production and reviews. Additionally, this process could provide a mechanism for

adding data elements to R1-VMP that were not in the original design or deliverable

products. These additional data elements could result in adaptations of base products for

specific analysis objectives or new specifically designed map products. 

Literature Cited

American Forest and Paper Association. 1992. Report of the Blue Ribbon Panel on forest inventory

and analysis. Washington, DC: 14 p.

American Forest and Paper Association. 1998. Forest inventory and analysis program: the report

of the Second Blue Ribbon Panel. Washington, DC: 17 p.

Avery, T.E. 1977. Interpretation of aerial photographs. Minneapolis, MN.

Baatz, M., U. Benz, S. Dehghani, M. Heynen. 2001. eCognition User. Guide 3, Definiens

Imaging GmbH, Munich, Germany.

Bailey, R.G., P.E. Avers, T. King, and W.H. McNab, eds. 1994. Ecoregions and subregions of the

United States (map). Washington, DC: U.S. Geological Survey. Scale 1:7,500,000; colored.

Accompanied by a supplementary table of map unit descriptions compiled and edited by W. H.

McNab and R.G. Bailey. Prepared for the U.S. Department of Agriculture, Forest Service. 

Bauer, M.E., T.E. Burk, A.R. Ek, and P.R. Coppin. 1994. Satellite inventory of Minnesota forest

resources. Photogrammetric Engineering and Remote Sensing 60(3): 287-298.

Boice, J.M. 1998. Genesis: an expositional commentary. Volume 1. Grand Rapids, MI: 464 p.

Bolstad, P.V. and T.M. Lillesand. 1992. Rule-based classification models: flexible integration of

satellite imagery and thematic spatial data. Photogrammetric Engineering and Remote Sensing,

58: 965-971.

Brewer, K., D. Berglund, C. Jacobson, and J. Barber. 2002. Northern Region Vegetation Mapping

Project. In: Jerry Dean Greer, ed, Rapid Delivery of Remote Sensing Products, Proceedings of

the Ninth Forest Service Remote Sensing Conference, American Society of Photogrammetry and

Remote Sensing. 

Brewer, C.K., J.A. Barber, G. Willhauck, and U.C. Benz. 2003. Multi-source and multi-classifier

system for regional landcover mapping. In: Proceedings of the IEEE workshop on Advances in

Techniques for Analysis of Remotely Sensed Data; NASA Goddard Space Flight Center, Greenbelt

MD, Institute of Electrical and Electronic Engineers; Geospatial and Remote Sensing Society.
3C-60 Existing Vegetation Classification & Mapping Technical Guide

Brewer, C.K., B. Schwind, R. Warbington, W. Clarke, and others. (In press). Existing vegetation

classification and mapping technical guide. In: Brohman, R. and L. Bryant, eds. Existing vegetation classification and mapping technical guide (Review Draft). U.S. Department of Agriculture,

Forest Service, Washington Office, Ecosystem Management Coordination Staff.

Brewer, C.K., J.C. Winne, R.L. Redmond, D. W. Opitz, and M.V. Mangrich. (In review).

Classifying and mapping wildfire severity: a comparison of methods. Photogrammetric

Engineering and Remote Sensing.

Brohman, R. and L. Bryant. (2005). Existing vegetation classification and mapping technical

guide. U.S. Department of Agriculture, Forest Service, Washington Office, Ecosystem

Management Coordination Staff. 

Brown, D.E., C.H. Lowe, and C.P. Pase. 1980. A digitized systematic classification for ecosystems

with an illustrated summary of the natural vegetation of North America. Gen. Tech. Rep. RM-73,

Fort Collins, CO: U.S. Department of Agriculture, Rocky Mountain Forest and Range

Experiment Station.

Brown, J.F., T.R. Loveland, J.W. Merchant, B.C. Reed, and D.O. Ohlen. 1993. Using multisource

data in global land-cover characterization: concepts, requirements, and methods. Photogrammetric

Engineering and Remote Sensing, 59: 977-987.

Buol, S.W., F.D. Hole, and R.J. McCracken. 1980. Soil genesis and classification. Second Edition.

Ames, Iowa: The Iowa State University Press: 406p.

Campbell, J.B. 1987. Introduction to remote sensing. Guilford Press, New York. USA.

Cetin, H. and D.W. Levandowski. 1991. Interactive classification and mapping of multi-dimensional

remotely sensed data using n-dimensional probability density functions (nPDF). Photogrammetric

Engineering and Remote Sensing, 57: 1579-1587.

Chuvieco, E. and R.G. Congalton. 1988. Using cluster analysis to improve the selection of training

statistics in classifying remotely sensed data. Photogrammetric Engineering and Remote Sensing,

54: 1275-1281.

Cibula, W.G. and M. O. Nyquist. 1987. Use of topographic and climatological models in a 

geographical data base to improve landsat MSS classification for Olympic National Park.

Photogrammetric Engineering and Remote Sensing, 53: 67-75.

Cohen, W.B. and T.A. Spies. 1992. Estimating structural attributes of Douglas-fir/western hemlock

forest stands from landsat and SPOT imagery. Remote Sensing of Environment, 41: 1-17.

Cohen, W.B., M. Florella, J. Gray, E. Helmer, and K. Anderson. 1998. An efficient and accurate

method for mapping forest clearcuts in the Pacific Northwest using Landsat imagery.

Photogrammetric Engineering and Remote Sensing, 64: 293-300.

Cohen, W.B., T.A. Spies, and M. Fiorella. 1995. Estimating the age and structure of forests in a

multi-ownership landscape of western Oregon, U.S.A. International Journal of Remote Sensing,

16: 721-746.
Existing Vegetation Classification & Mapping Technical Guide 3C-61

Cooper,S.V., K.E. Neiman, and D.W. Roberts. 1991. Forest habitat types of northern Idaho: a

second approximation. Gen. Tech. Rep. INT-236. Ogden, UT: U.S. Department of Agriculture,

Forest Service, Intermountain Research Station. 143 p.

Coppin, P.R. and M.E. Bauer. 1994. Processing of multitemporal landsat TM imagery to optimize

extraction of forest cover change features. IEEE Geoscience and Remote Sensing, 60(3): 287-298.

Coppin, P.R. and M.E. Bauer. 1995. The potential contribution of pixel-based canopy change information to stand-based forest management in the northern U.S. J. Environ Manage., 44: 69-82.

Coppin, P.R. and M.E. Bauer. 1996. Digital change detection in forest ecosystems with remote

sensing imagery. Remote Sensing Reviews, 13: 207-234. 

Coppin, P., K. Nackaerts, L. Queen, and K. Brewer. 2001. Operational monitoring of green biomass

change for forest management. Photogramm. Eng. Remote Sensing, 67(5): 603-611.

Cowardin, L.M., V. Carter, F.C. Golet, and E. T. LaRoe 1979. Classification of wetlands and

deepwater habitats of the United States. Washington, DC: U.S. Department of the Interior, Fish

and Wildlife Service: 103p.

Cross, A.M., D.C. Mason, and S.J. Dury. 1988. Segmentation of remotely-sensed images by a

split-and-merge process. International Journal of Remote Sensing, 9: 1329-1345.

Czaplewski, R.L. 1999. Toward an annual national inventory. Journal of Forestry, Dec/1999: 44-48.

Deppe, F. 1998. Forest area estimation using sample surveys and landsat MSS and TM data.

Photogrammetric Engineering and Remote Sensing, 64: 285-292.

Dikshit, O. and D.P. Roy. 1996. An empirical investigation of image resampling effects upon the

spectral and textural supervised classification of a high spatial resolution multispectral image.

Photogrammetric Engineering and Remote Sensing, 62: 1085-1092.

Federal Geographic Data Committee. 1977. Vegetation Subcommittee. Vegetation classification

standard. FGDC-STD-005. Federal Geographic Data Committee, U.S. Geological Survey,

Reston, Virginia, USA. [Available online: http://www.fgdc.gov/standards/documents/standards/

vegetation/vegclass.pdf]

Federal Geographic Data Committee. 1996. FGDC Standards Reference Model. Federal

Geographic Data Committee, U.S. Geological Survey, Reston, Virginia, USA.

Flowers, P., R. Conner, D. Jackson, C. Keegan, and others. 1993. An assessment—Montana’s

timber supply situation, Misc. Publ. 53, Montana Forest and Conservation Experiment Sta.,

Missoula, MT.

Foody, G.M., N.A. Campbell, N.M. Trodd, and T.F. Wood. 1992. Derivation and applications of

probabilistic measures of class membership from the maximum-likelihood classification.

Photogrammetric Engineering and Remote Sensing, 58: 1335-1341.

Ford-Robertson, F.C. 1971. Terminology of forest science, technology practice and products. The

multilingual forestry terminology series 1. Society of American Foresters, Washington D.C., USA.
3C-62 Existing Vegetation Classification & Mapping Technical Guide

Forman, R.T.T. 1995. Land mosaics: the ecology of landscapes and regions. NY: Cambridge

University Press, USA.

Forman, R.T.T. and M. Godron. 1986. Landscape ecology. NY: John Wiley and Sons, USA.

Franklin, S.E. and D.R. Peddle. 1990. Classification of SPOT HRV imagery and texture features.

International Journal of Remote Sensing, 11: 551-556.

Fung, T. and E. LeDrew. 1987. Application of principal components analysis to change detection.

Photogrammetric Engineering and Remote Sensing, 53: 1649-1658.

Gauch, H.G. 1982. Multivariate analysis in community ecology. NY: Cambridge University Press,

USA. 298p.

Gerstner, J. 1980. Man as God made him. In: Boice, J. M., editor. Our Savior: man, Christ, and

the Atonement. Grand Rapids, MI: Baker Books, USA.

Gillespie, A.J.R. 1999. Rationale for a national annual forest inventory program. Journal of

Forestry, 97(12): 16-20.

Gmelin, M. and K. Brewer. 2002. Operational change detection-based fire severity mapping

using Landsat TM+ Data. In: Rapid delivery of remote sensing products; Proceedings of the

Ninth Forest Service Remote Sensing Conference, American Society of Photogrammetry and

Remote Sensing; Jerry Dean Greer, ed. 

Gong, P. and P.J. Howarth. 1992. Frequency-based contextual classification and gray-level vector

reduction for land-use identification. Photogrammetric Engineering and Remote Sensing, 58:

423-437.

Gong, P., D.J. Marceau, and P.J. Howarth. 1992. A comparison of spatial feature extraction algorithms for land-use classification with SPOT HRV data. Remote Sensing of Environment, 40:

137-151.

Goodchild, M.F. 1994. Integrating GIS and remote sensing for vegetation analysis and modeling:

methodological issues. J Veg. Sci., 5: 615-626. 

Gopal, S. and C. Woodcock. 1994. Theory and methods for accuracy assessments of thematic

maps using fuzzy sets. Photogrammetric Engineering and Remote Sensing, 60: 181-188.

Graves, H. S. 1913. Forest mensuration. John Wiley and Sons, New York, NY, USA.

Green, K., D. Kempka, and L. Lackey. 1994. Using remote sensing to detect and monitor landcover and land-use change. Photogrammetric Engineering and Remote Sensing, 60: 331-337.

Haralick, R.M. and L.G. Shapiro. 1985. Image segmentation techniques. Comput. Vis. Image

Understand, 29: 100-132. 

Hartgerink, A.P. and F.A. Bazzaz. 1984. Seedling-scale environmental heterogeneity influences

individual fitness and population structure. Ecology, 65: 198-206.
Existing Vegetation Classification & Mapping Technical Guide 3C-63

Hashem, M., M. El-Khattib, N. El-Mowelhi, and H. Hetoh. 1996. Monitoring land cover of the

desert fringes of the eastern Nile delta, Egypt, Proceedings of the IGARSS 1996 Symposium,

27-31 May, Lincoln, NE, 3: 1756-1758.

Heath, L.S. and R.A. Birdsey. 1997. A model for estimating the U.S. forest carbon budget. In: R.

Birdsey, R. Mickler, D. Sandberg, R. Tinus, and others, eds. USDA Forest Service global change

research program highlights: 1991-1995. Gen. Tech. Rep. NE-237; Radnor, PA: U.S. Department

of Agriculture, Forest Service, Northeastern Forest Experiment Station.

Helms, J.A., editor. 1998. The dictionary of forestry. Society of American Foresters, Bethesda,

Maryland, USA.

Hogda, K.A., H. Tommervik, I. Solheim, and I. Lauknes. 1995. Mapping of air pollution effects

on the vegetation cover in the Kikenes-Nikel area using remote sensing, Proceedings of the

IGARSS 1995 Symposium, 10-14 July, Florence, Italy, 2: 1249-1251.

Jakubauskas, M.E. 1997. Effects of forest succession on texture in landsat thematic mapper

imagery. Canadian Journal of Remote Sensing, 23: 257-263.

Janssen, L.L.F., M.N. Jaarsma, and E.T. M van der Linden. 1990. Integrating topographic data

with remote sensing for land-cover classification. Photogrammetric Engineering and Remote

Sensing, 56: 1503-1506.

Jennings, M., D. Faber-Langendoen, D. Glenn-Lewin, R. Peet, and others. 2004. Standards for

associations and alliances of the U.S. national vegetation classification. Version 1.0. Vegetation

Classification Panel, Ecological Society of America, Washington, D.C., USA.

Jensen, M., I. Goodman, K. Brewer, T. Frost, G. Ford, and J. Nesser. 1997. Biophysical environments

of the basin. In: An assessment of the ecosystem components in the Interior Columbia Basin

and portions of the Klamath and Great Basins; T. Quigley and S. Arbelbide, tech eds. Vol. I.,

PNW-GTR-405, Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific

Northwest Research Station.

Johnston, J.J., D.R. Weigel, and J.C. Randolph. 1997. Satellite remote sensing: an inexpensive

tool for pine plantation management. Journal of Forestry, 95: 16-20.

Jones, J. , K. Brewer, G. Enstrom, and J. Caratti. 1998. Documentation of the modeling of potential

vegetation settings and vegetation response units using topographic variables, Missoula, MT:

U.S. Department of Agriculture, Forest Service, Northern Region.

Jones, J., Project Leader. 2002. Potential natural vegetation (PNV) classification of western and

central Montana, and northern Idaho. Northern Region, National Fire Plan Cohesive Strategy

Team, Kalispell, MT: U.S. Department of Agriculture, Northern Region [Available online:

http://www.fs.fed.us/r1/cohesive_strategy/].

Kauth, R.J. and G.S. Thomas. 1976. The tasseled cap—a graphic description of the spectral-temporal

development of agricultural crops as seen by Landsat. Proceedings of the Symposium on Machine

Processing of Remotely Sensed Data, Purdue, University, West Lafayette, IN, 4b: 41-51. 
3C-64 Existing Vegetation Classification & Mapping Technical Guide

Key, C.H. and N.C. Benson. 1999. The normalized burn ration, a Landsat TM radiometric index

of burn severity incorporating multi-temporal differencing. U. S. Geological Survey, Unpublished

manuscript. 

Kimmins, J.P. 1997. Forest ecology: a foundation for sustainable management. Second edition.

NJ: Prentice Hall, Upper Saddle River, USA.

Lachowski, H., P. Hardwick, R. Griffith, A. Parsons, and R. Warbington. 1997. Faster, better data

for burned watersheds needing emergency rehab. Journal of Forestry, 95: 4-8.

Lachowski, H., P. Maus, M. Golden, J. Johnson, and others. 1996. Guidelines for the use of digital

imagery for vegetation mapping. EM-7140-25. U.S. Department of Agriculture, Forest Service,

Engineering Staff, Washington, DC.

Leprieur, C.E. and J M. Durand. 1988. Influence of topography on forest reflectance using landsat

thematic mapper and digital terrain data. Photogrammetric Engineering and Remote Sensing, 54:

491-496.

Lillesand, T.M. and R.W. Kiefer. 1987. Remote sensing and image interpretation. Second edition.

NY: John Wiley and Sons, USA.

Lillesand, T.M. and R.W. Kiefer. 2000. Remote sensing and image interpretation. Fourth edition.

NY: John Wiley & Sons, USA.

Lincoln, R.J., G.A. Boxshall, and P.F. Clark. 1982. A dictionary of ecology, evolution and systematics. NY: Cambridge University Press, USA.

Lo, C.P. and L.J. Watson. 1998. The influence of geographic sampling methods on vegetation

map accuracy evaluation in a swampy environment. Photogrammetric Engineering and Remote

Sensing, 64: 1189-1200.

Loveland, T.R., J.W. Merchant, D.O. Ohlen, and J.F. Brown. 1991. Development of land-cover

characteristics database for the conterminous U.S. Photogrammetric Engineering and Remote

Sensing, 57: 1453-1463.

Mahlke, J. 1996. Characterization of Oklahoma reservoir wetlands for preliminary change detection

mapping using IRS-1B satellite imagery. Proceedings of the IGARSS 1996 Symposium, Lincoln,

NB, USA, 3: 1769-1771.

Marceau, D.J., P.J. Howarth, J.M.M. Dubois, and D.J. Gratton. 1990. Evaluation of the grey-level

co-occurrence matrix method for land-cover classification using SPOT imagery. IEEE

Transactions on Geoscience and Remote Sensing, 28 :513-519.

McDonald, T., K. Brewer, T. Grover, and B. Young. 2002. Map feature delineation in the northern

region vegetation mapping project. In: Proceedings of the Ninth Forest Service Remote Sensing

Conference, April 8–12, 2002, San Diego, CA. Bethesda, MD; American Society of

Photogrammetry and Remote Sensing. Unpaginated CD-Rom. 
Existing Vegetation Classification & Mapping Technical Guide 3C-65

McNab, W.H. and P.E. Avers, comps. 1994. Ecological Subregions of the United States: Section

Descriptions. Admin. Publ. WO-WSA-5. Washington, DC: U.S. Department of Agriculture,

Forest Service. 267p.

Mickelson, J.G., D.L. Civco, and J.A. Silander, Jr. 1998. Delineating forest canopy species in the

northeastern United States using multi-temporal TM imagery. Photogrammetric Engineering and

Remote Sensing, 64:891-904.

Mill, J.S. 1846. System of logic, ratiocinative and inductive. NY: Harper and Brothers: 593p.

Mosby, H.S. 1980. Reconnaissance mapping and map use. In: Schemnitz, S.D., ed. Wildlife

management techniques manual. The Wildlife Society, Washington, DC.

Mueggler, W.F. and W.L Stewart. 1980. Grassland and shrubland habitat types of western

Montana. Gen. Tech. Rep. INT-66. Ogden, UT: U.S. Department of Agriculture, Forest Service,

Intermountain Research Station. 154 p. 

Mueller-Dombois, D. and H. Ellenberg. 1974. Aims and methods of vegetation ecology. NY:

John Wiley and Sons, USA.

Ngai, F.M. and J.J. Curlander. 1994. Model-based feature classification and change detection.

Proceedings of the IGARR 1994 Symposium, California Institute of Technology, Pasadena, CA.

4: 2531-2533. 

Oliver, C.D. and B.C. Larson. 1990. Forest stand dynamics. McGraw Hill, New York, NY, USA.

Parra, G.A., M. Mouchot, and C. Mouchot. 1996. A multitemporal land-cover change analysis

tool using change vector and principal components analysis. Proceedings of the IGARSS 1996

Symposium, Burnham Yates Conference Center, Lincoln, NB, USA, 3: 1753-1755. 

Peddle, D.R. and S.E. Franklin. 1991. Image texture processing and data integration for surface

pattern discrimination. Photogrammetric Engineering and Remote Sensing, 57: 413-420.

Pfister, R.D. and S.F. Arno. 1980. Classifying forest habitat types based on potential climax

vegetation. Forest Sci, 26(1): 52-70.

Pfister, R.D., B.L. Kovalchik, S.F. Arno, and R.C. Presby. 1977. Forest habitat types of Montana.

INT-34, Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Forest and

Range Experiment Station. 

Picket, S.T.A. and P.S. White. 1985. The ecology of natural disturbance and path dynamics. San

Diego, CA: Academic Press, Inc.: 472 p.

Reams, G.A. and P.C. VanDeusen. 1999. The southern annual inventory system. Journal of

Agricultural, Biological, and Environmental Statistics, 4(3): 108-122.

Reams, G.A., F.A. Roesch, and N.D. Cost. 1999. Annual forest inventory: cornerstone of sustainability in the South. Journal of Forestry, 97(12): 21-26.
3C-66 Existing Vegetation Classification & Mapping Technical Guide

Redmond, R.L., Z. Ma, T.P. Tady, and J.C. Winne. 1996. Mapping existing vegetation and land

cover across western Montana and northern Idaho. Final Report, Contract No. 53-0343-4-000012.

Missoula, MT: U.S. Department of Agriculture, Forest Service, Northern Region. 

Robinson, J.W. and J.C. Tilton. 1991. Refinement of ground reference data with segmented

image data. Proceedings of the IEEE and NASA Goddard Space Flight Center, Publ. 3099,

University of Maryland, 14-15 June. 

Ryherd, S. and C. Woodcock. 1996. Combining spectral and texture data in the segmentation of

remotely sensed images. Photogrammetric Engineering and Remote Sensing, 62: 181-194.

Scheiner, S.M. 1992. Measuring pattern diversity. Ecology, 73: 1860-1867.

Shandley, J., J. Franklin, and T. White. 1996. Testing the Woodcock-Harward image segmentation

algorithm in an area of Southern California chaparral and woodland vegetation. International

Journal of Remote Sensing, 17: 983-1004.

Shasby, M. and D. Carneggie. 1986. Vegetation and terrain mapping in Alaska using landsat MSS

and digital terrain data. Photogrammetric Engineering and Remote Sensing, 52: 779-786.

Smith, D.M. 1986. The practice of silviculture. John Wiley and Sons, New York, NY, USA.

Society of American Foresters. 2000. The forest inventory and analysis (FIA) program. Society

of American Foresters, Bethesda, MD.

Solheim, I., K.A. Hogda, and H. Tommervik. 1995. Detection of abnormal vegetation change in

the Monchegorsk, Russia, area. Proceedings of the IGARSS 1995 Symposium, 10-14 July,

Florence, Italy, 1: 105-107.

Stage, A.R. and J.R. Alley. 1972. An inventory design using stand examinations for planning and

programming timber management. Res. Paper RP-INT-126. U. S. Department of Agriculture,

Forest Service. 

Stoms, D.M., M.I. Bueno, F.W. Davis, K.M. Cassidy, and others. 1998. Map guided classification

of regional land cover with multi-temporal AVHRR data. Photogrammetric Engineering and

Remote Sensing, 64: 831-838.

Story, M. and R.G. Congalton. 1986. Accuracy assessment: a user’s perspective.

Photogrammetric Engineering and Remote Sensing, 52: 397–399.

Strahler, A.H. 1980. The use of prior probabilities in maximum likelihood classification of

remotely sensed data. Remote Sensing of Environment, 10: 135-163.

Toumey, J.W. 1937. Foundations of silviculture upon an ecological basis. NY: John Wiley and

Sons, USA.

Trewartha, G.T. 1968. An introduction to climate. Fourth Edition. NY: McGraw-Hill Book Company

U.S. Department of Agriculture, Forest Service, Soil Survey Division Staff. 1993. Soil survey

manual. U.S. Department of Agriculture, Soil Conservation Service, Handbook 18, Washington, DC.
Existing Vegetation Classification & Mapping Technical Guide 3C-67

VanDeusen, P.C., S.P. Prisley, and A.A. Lucier. 1999. Adopting an annual inventory system: user

perspectives. Journal of Forestry, 97(12): 11-14. 

Woodcock, C.E. and S. Gopal. 1992. Accuracy assessment of the Stanislaus Forest vegetation

map using fuzzy sets. Proceedings of the Fourth Biennial Remote Sensing Applications

Conference, Orlando, FL, April ASPRS, Bethesda, MD: 378-394.

Woodcock, C.E., S. Macomber, S. Ryherd, and Y. Wu. 1994. Mapping forest vegetation using

landsat TM imagery and a canopy reflectance model. Remote Sensing of Environment, 50: 240-254.

Wynne, J., and D. Carter. 1977. Will remote sensing live up to its promise? Journal of Forestry,

95(10).
3C-68 Existing Vegetation Classification & Mapping Technical Guide
Existing Vegetation Classification & Mapping Technical Guide 3D-1

Appendix 3D

Metadata Development Questions

This appendix was taken from the following U.S. Geological Survey Web site:

http://geology.usgs.gov/tools/metadata/tools/doc/ctc/.

Metadata in Plain Language

Introduction

This document provides a general interview approach for creating metadata. It is not necessarily exhaustive but is intended to convey in plain language the basic information

that will be contained in the metadata and link to pages specifying the steps required to

write that information into the metadata document itself. Questions in italics indicate

the topics and are not to be answered explicitly; those that are in plain text, indented

beneath them are the questions that need to be answered.

The Questions

1. What does the data set describe?

a. What is the title of the data set? 

b. What geographic area does the data set cover? 

c. Does the data set describe conditions during a particular time period? 

d. Is this a digital map or remote-sensing image, or something different like tabular

data? 

e. How does the data set represent geographic features?

1. How are geographic features stored in the data set? 

2. What coordinate system is used to represent geographic features? 

f. How does the data set describe geographic features?

1. What are the types of features present? 

2. For each feature, what attributes of these features are described? 

3. What sort of values does each attribute hold? 

4. For measured attributes, what are the units of measure, resolution of the 

measurements, frequency of the measurements in time, and estimated 

accuracy of the measurements? 

2. Who produced the data set? 

a. Who created the data set? 

1. Formal authors of the published work. 

2. Compilers and editors who converted the work to digital form.
3D-2 Existing Vegetation Classification & Mapping Technical Guide

3. Technical specialists who did some of the processing but aren’t listed as 

formal authors. 

4. Cooperators, collaborators, funding agencies, and other contributors who 

deserve mention. 

b. To whom should users address questions about the data? 

3. Why was the data set created?

a. What were the objectives of the research that resulted in this data set? 

b. What objectives are served by presenting the data in digital form? 

c. How do you recommend that the data be used? 

d. Are you concerned that nonspecialists might misinterpret the data? If so, of 

what aspects of the data set should they be especially wary? 

4. How was the data set created? 

a. From what previous works were the data drawn?

1. Are the source data original observations made by the authors and their 

cooperators? 

2. Were parts of the data previously packaged in a publication or distributed 

informally? 

3. Were the source data published? 

4. Were the source data compiled at a particular scale? 

5. What time period do the source data represent? 

6. What information was obtained from each data source? 

b. How were the data generated, processed, and modified?

1. How were the data collected, handled, or processed? 

2. For this activity did you use data from some other source? 

3. Did this activity generate an intermediate data product that stands on its own?

4. When did this processing occur? 

5. Did someone other than the formal authors do the data processing? 

c. What similar or related data should the user be aware of? 

5. How reliable are the data; what problems remain in the data set?

a. What can you say about the accuracy of the observations? 

b. How accurately are the geographic locations known? 

c. If data vary in depth or height, how accurately is vertical position known? 

d. Where are the gaps in the data? What is missing there? 

e. Do the observations mean the same thing throughout the data set? 
Existing Vegetation Classification & Mapping Technical Guide 3D-3

6. How can someone get a copy of the data set?

a. Are there legal restrictions on access or use of the data? 

b. Who distributes the data? 

c. What is the distributor's name or number for this data set? 

d. As a distributor, what legal disclaimers do you want users to read? 

e. How can people download or order the data? 

1. In what formats are the data available? 

2. Can users download the data from the network? 

3. Can users get the data on disk or tape? 

4. Is there a fee to get the data? 

5. How long will it take to get the data? 

f. What hardware or software do people need in order to use the data set? 

g. Will these data be available for only a limited time? 

7. Who wrote the metadata? 

a. When were the metadata last modified? 

b. Has this metadata record been reviewed or will it be reviewed in the future? 

c. Who wrote the metadata? 

d. To what standard are the metadata intended to conform? 

e. If you specified any clock times in the metadata, did you use local time, GMT, 

or something else? 

f. Are there legal restrictions on who can get or use the metadata?
3D-4 Existing Vegetation Classification & Mapping Technical Guide
Existing Vegetation Classification & Mapping Technical Guide 3E-1

Appendix 3E. 

Standard Metadata Template

This appendix was taken from the U. S. Geological Survey Web site at

http://geology.usgs.gov/tools/metadata/tools/doc/template.

FGDC Metadata Template

Metadata:

Identification_Information:

Citation:

Citation_Information:

Originator:

Publication_Date:

Publication_Time:

Title:

Edition:

Geospatial_Data_Presentation_Form:

Series_Information:

Series_Name:

Issue_Identification:

Publication_Information:

Publication_Place:

Publisher:

Other_Citation_Details:

Online_Linkage:

Larger_Work_Citation:

Citation_Information:

Description:

Abstract:

Purpose:

Supplemental_Information:

Time_Period_of_Content:

Time_Period_Information:
3E-2 Existing Vegetation Classification & Mapping Technical Guide

Single_Date/Time:

Calendar_Date:

Time_of_Day:

Multiple_Dates/Times:

Single_Date/Time:

Calendar_Date:

Time_of_Day:

Range_of_Dates/Times:

Beginning_Date:

Beginning_Time:

Ending_Date:

Ending_Time:

Currentness_Reference:

Status:

Progress:

Maintenance_and_Update_Frequency:

Spatial_Domain:

Bounding_Coordinates:

West_Bounding_Coordinate:

East_Bounding_Coordinate:

North_Bounding_Coordinate:

South_Bounding_Coordinate:

Data_Set_G-Polygon:

Data_Set_G-Polygon_Outer_G-Ring:

G-Ring_Point:

G-Ring_Latitude:

G-Ring_Longitude:

G-Ring:

Data_Set_G-Polygon_Exclusion_G-Ring:

G-Ring_Point:

G-Ring_Latitude:

G-Ring_Longitude:

G-Ring:

Keywords:

Theme:

Theme_Keyword_Thesaurus:

Theme_Keyword:

Place:

Place_Keyword_Thesaurus:

Place_Keyword:
Existing Vegetation Classification & Mapping Technical Guide 3E-3

Stratum:

Stratum_Keyword_Thesaurus:

Stratum_Keyword:

Temporal:Temporal_Keyword_Thesaurus: Temporal_Keyword:

Access_Constraints:

Use_Constraints: Point_of_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person:

Contact_Organization:

Contact_Organization_Primary:

Contact_Organization:

Contact_Person:

Contact_Position:

Contact_Address:

Address_Type:

Address:

City:

State_or_Province: Postal_Code:

Country:

Contact_Voice_Telephone:

Contact_TDD/TTY_Telephone:

Contact_Facsimile_Telephone:

Contact_Electronic_Mail_Address:

Hours_of_Service:

Contact_Instructions:

Browse_Graphic:

Browse_Graphic_File_Name:

Browse_Graphic_File_Description:

Browse_Graphic_File_Type:

Data_Set_Credit:

Security_Information:

Security_Classification_System:

Security_Classification:

Security_Handling_Description:
3E-4 Existing Vegetation Classification & Mapping Technical Guide

Native_Data_Set_Environment:

Cross_Reference:

Citation_Information:

Originator:

Publication_Date:

Publication_Time:

Title:

Edition:

Geospatial_Data_Presentation_Form:

Series_Information:

Series_Name:

Issue_Identification:

Publication_Information:

Publication_Place:

Publisher:

Other_Citation_Details:

Online_Linkage:

Larger_Work_Citation:

Citation_Information:

Data_Quality_Information:

Attribute_Accuracy:

Attribute_Accuracy_Report:

Quantitative_Attribute_Accuracy_Assessment:

Attribute_Accuracy_Value:

Attribute_Accuracy_Explanation:

Logical_Consistency_Report:

Completeness_Report:

Positional_Accuracy:

Horizontal_Positional_Accuracy:

Horizontal_Positional_Accuracy_Report:

Quantitative_Horizontal_Positional_Accuracy_Assessment:

Horizontal_Positional_Accuracy_Value:

Horizontal_Positional_Accuracy_Explanation:

Vertical_Positional_Accuracy:

Vertical_Positional_Accuracy_Report:

Quantitative_Vertical_Positional_Accuracy_Assessment:

Vertical_Positional_Accuracy_Value:

Vertical_Positional_Accuracy_Explanation:

Lineage:

Source_Information:
Existing Vegetation Classification & Mapping Technical Guide 3E-5

Source_Citation:

Citation_Information:

Originator:

Publication_Date:

Publication_Time:

Title:

Edition:

Geospatial_Data_Presentation_Form:

Series_Information:

Series_Name:

Issue_Identification:

Publication_Information:

Publication_Place:

Publisher:

Other_Citation_Details:

Online_Linkage:

Larger_Work_Citation:

Citation_Information:

Source_Scale_Denominator:

Type_of_Source_Media:

Source_Time_Period_of_Content:

Time_Period_Information:

Single_Date/Time:

Calendar_Date:

Time_of_Day:

Multiple_Dates/Times:

Single_Date/Time:

Calendar_Date:

Time_of_Day:

Range_of_Dates/Times:

Beginning_Date:

Beginning_Time:

Ending_Date:

Ending_Time:

Source_Currentness_Reference:

Source_Citation_Abbreviation:

Source_Contribution:

Process_Step:

Process_Description:
3E-6 Existing Vegetation Classification & Mapping Technical Guide

Source_Used_Citation_Abbreviation:

Process_Date:

Process_Time:

Source_Produced_Citation_Abbreviation:

Process_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person:

Contact_Organization:

Contact_Organization_Primary:

Contact_Organization:

Contact_Person:

Contact_Position:

Contact_Address:

Address_Type:

Address:

City:

State_or_Province:

Postal_Code:

Country:

Contact_Voice_Telephone:

Contact_TDD/TTY_Telephone:

Contact_Facsimile_Telephone:

Contact_Electronic_Mail_Address:

Hours_of_Service:

Contact_Instructions:

Cloud_Cover:

Spatial_Data_Organization_Information:

Indirect_Spatial_Reference:

Direct_Spatial_Reference_Method:

Point_and_Vector_Object_Information:

SDTS_Terms_Description:

SDTS_Point_and_Vector_Object_Type:

Point_and_Vector_Object_Count:

VPF_Terms_Description:

VPF_Topology_Level:

VPF_Point_and_Vector_Object_Information:

VPF_Point_and_Vector_Object_Type:

Point_and_Vector_Object_Count:
Existing Vegetation Classification & Mapping Technical Guide 3E-7

Raster_Object_Information:

Raster_Object_Type:

Row_Count:

Column_Count:

Vertical_Count:

Spatial_Reference_Information:

Horizontal_Coordinate_System_Definition:

Geographic:

Latitude_Resolution:

Longitude_Resolution:

Geographic_Coordinate_Units:

Planar:

Map_Projection:

Map_Projection_Name:

Albers_Conical_Equal_Area:

Standard_Parallel:

Longitude_of_Central_Meridian:

Latitude_of_Projection_Origin:

False_Easting:

False_Northing:

Azimuthal_Equidistant:

Longitude_of_Central_Meridian:

Latitude_of_Projection_Origin:

False_Easting:

False_Northing:

Equidistant_Conic:

Standard_Parallel:

Longitude_of_Central_Meridian:

Latitude_of_Projection_Origin:

False_Easting:

False_Northing:

Equirectangular:

Standard_Parallel:

Longitude_of_Central_Meridian:

False_Easting:

False_Northing:

General_Vertical_Near-sided_Perspective:

Height_of_Perspective_Point_Above_Surface:

Longitude_of_Projection_Center:
3E-8 Existing Vegetation Classification & Mapping Technical Guide

Latitude_of_Projection_Center:

False_Easting:

False_Northing:

Gnomonic:

Longitude_of_Projection_Center:

Latitude_of_Projection_Center:

False_Easting:

False_Northing:

Lambert_Azimuthal_Equal_Area:

Longitude_of_Projection_Center:

Latitude_of_Projection_Center:

False_Easting:

False_Northing:

Lambert_Conformal_Conic:

Standard_Parallel:

Longitude_of_Central_Meridian:

Latitude_of_Projection_Origin:

False_Easting:

False_Northing:

Mercator:

Standard_Parallel:

Scale_Factor_at_Equator:

Longitude_of_Central_Meridian:

False_Easting:

False_Northing:

Modified_Stereographic_for_Alaska:

False_Easting:

False_Northing:

Miller_Cylindrical:

Longitude_of_Central_Meridian:

False_Easting:

False_Northing:

Oblique_Mercator:

Scale_Factor_at_Center_Line:

Oblique_Line_Azimuth:

Azimuthal_Angle:

Azimuth_Measure_Point_Longitude:

Oblique_Line_Point:

Oblique_Line_Latitude:
Existing Vegetation Classification & Mapping Technical Guide 3E-9

Oblique_Line_Longitude:

Latitude_of_Projection_Origin:

False_Easting:

False_Northing:

Orthographic:

Longitude_of_Projection_Center:

Latitude_of_Projection_Center:

False_Easting:

False_Northing:

Polar_Stereographic:

Straight-Vertical_Longitude_from_Pole:

Standard_Parallel:

Scale_Factor_at_Projection_Origin:

False_Easting:

False_Northing:

Polyconic:

Longitude_of_Central_Meridian:

Latitude_of_Projection_Origin:

False_Easting:

False_Northing:

Robinson:

Longitude_of_Projection_Center:

False_Easting:

False_Northing:

Sinusoidal:

Longitude_of_Central_Meridian:

False_Easting:

False_Northing:

Space_Oblique_Mercator_(Landsat):

Landsat_Number:

Path_Number:

False_Easting:

False_Northing:

Stereographic:

Longitude_of_Projection_Center:

Latitude_of_Projection_Center:

False_Easting:

False_Northing:

Transverse_Mercator:
3E-10 Existing Vegetation Classification & Mapping Technical Guide

Scale_Factor_at_Central_Meridian:

Longitude_of_Central_Meridian:

Latitude_of_Projection_Origin:

False_Easting:

False_Northing:

van_der_Grinten:

Longitude_of_Central_Meridian:

False_Easting:

False_Northing:

Map_Projection_Parameters:

Grid_Coordinate_System:

Grid_Coordinate_System_Name:

Universal_Transverse_Mercator:

UTM_Zone_Number:

Transverse_Mercator:

Scale_Factor_at_Central_Meridian:

Longitude_of_Central_Meridian:

Latitude_of_Projection_Origin:

False_Easting:

False_Northing:

Universal_Polar_Stereographic:

UPS_Zone_Identifier:

Polar_Stereographic:

Straight-Vertical_Longitude_from_Pole:

Standard_Parallel:

Scale_Factor_at_Projection_Origin:

False_Easting:

False_Northing:

State_Plane_Coordinate_System:

SPCS_Zone_Identifier:

Lambert_Conformal_Conic:

Standard_Parallel:

Longitude_of_Central_Meridian:

Latitude_of_Projection_Origin:

False_Easting:

False_Northing:

Transverse_Mercator:

Scale_Factor_at_Central_Meridian:

Longitude_of_Central_Meridian:
Existing Vegetation Classification & Mapping Technical Guide 3E-11

Latitude_of_Projection_Origin:

False_Easting:

False_Northing:

Oblique_Mercator:

Scale_Factor_at_Center_Line:

Oblique_Line_Azimuth:

Azimuthal_Angle:

Azimuth_Measure_Point_Longitude:

Oblique_Line_Point:

Oblique_Line_Latitude:

Oblique_Line_Longitude:

Latitude_of_Projection_Origin:

False_Easting:

False_Northing:

Polyconic:

Longitude_of_Central_Meridian:

Latitude_of_Projection_Origin:

False_Easting:

False_Northing:

ARC_Coordinate_System:

ARC_System_Zone_Identifier:

Equirectangular:

Standard_Parallel:

Longitude_of_Central_Meridian:

False_Easting:

False_Northing:

Azimuthal_Equidistant:

Longitude_of_Central_Meridian:

Latitude_of_Projection_Origin:

False_Easting:

False_Northing:

Other_Grid_System’s_Definition:

Local_Planar:

Local_Planar_Description:

Local_Planar_Georeference_Information:

Planar_Coordinate_Information:

Planar_Coordinate_Encoding_Method:

Coordinate_Representation:

Abscissa_Resolution:
3E-12 Existing Vegetation Classification & Mapping Technical Guide

Ordinate_Resolution:

Distance_and_Bearing_Representation:

Distance_Resolution:

Bearing_Resolution:

Bearing_Units:

Bearing_Reference_Direction:

Bearing_Reference_Meridian:

Planar_Distance_Units:

Local:

Local_Description:

Local_Georeference_Information:

Geodetic_Model:

Horizontal_Datum_Name:

Ellipsoid_Name:

Semi-major_Axis:

Denominator_of_Flattening_Ratio:

Vertical_Coordinate_System_Definition:

Altitude_System_Definition:

Altitude_Datum_Name:

Altitude_Resolution:

Altitude_Distance_Units:

Altitude_Encoding_Method:

Depth_System_Definition:

Depth_Datum_Name:

Depth_Resolution:

Depth_Distance_Units:

Depth_Encoding_Method:

Entity_and_Attribute_Information:

Detailed_Description:

Entity_Type:

Entity_Type_Label:

Entity_Type_Definition:

Entity_Type_Definition_Source:

Attribute:

Attribute_Label:

Attribute_Definition:

Attribute_Definition_Source:

Attribute_Domain_Values:

Enumerated_Domain:
Existing Vegetation Classification & Mapping Technical Guide 3E-13

Enumerated_Domain_Value:

Enumerated_Domain_Value_Definition:

Enumerated_Domain_Value_Definition_Source:

Attribute:

Range_Domain:

Range_Domain_Minimum:

Range_Domain_Maximum:

Attribute_Units_of_Measure:

Attribute_Measurement_Resolution:

Attribute:

Codeset_Domain:

Codeset_Name:

Codeset_Source:

Unrepresentable_Domain:

Beginning_Date_of_Attribute_Values:

Ending_Date_of_Attribute_Values:

Attribute_Value_Accuracy_Information:

Attribute_Value_Accuracy:

Attribute_Value_Accuracy_Explanation:

Attribute_Measurement_Frequency:

Overview_Description:

Entity_and_Attribute_Overview:

Entity_and_Attribute_Detail_Citation:

Distribution_Information:

Distributor:

Contact_Information:

Contact_Person_Primary:

Contact_Person:

Contact_Organization:

Contact_Organization_Primary:

Contact_Organization:

Contact_Person:

Contact_Position:

Contact_Address:

Address_Type:

Address:

City:

State_or_Province:

Postal_Code:
3E-14 Existing Vegetation Classification & Mapping Technical Guide

Country:

Contact_Voice_Telephone:

Contact_TDD/TTY_Telephone:

Contact_Facsimile_Telephone:

Contact_Electronic_Mail_Address:

Hours_of_Service:

Contact_Instructions:

Resource_Description:

Distribution_Liability:

Standard_Order_Process:

Non-digital_Form:

Digital_Form:

Digital_Transfer_Information:

Format_Name:

Format_Version_Number:

Format_Version_Date:

Format_Specification:

Format_Information_Content:

File_Decompression_Technique:

Transfer_Size:

Digital_Transfer_Option:

Online_Option:

Computer_Contact_Information:

Network_Address:

Network_Resource_Name:

Dialup_Instructions:

Lowest_BPS:

Highest_BPS:

Number_DataBits:

Number_StopBits:

Parity:

Compression_Support:

Dialup_Telephone:

Dialup_File_Name:

Access_Instructions:

Online_Computer_and_Operating_System:

Offline_Option:

Offline_Media:

Recording_Capacity:
Existing Vegetation Classification & Mapping Technical Guide 3E-15

Recording_Density:

Recording_Density_Units:

Recording_Format:

Compatibility_Information:

Fees:

Ordering_Instructions:

Turnaround:

Custom_Order_Process:

Technical_Prerequisites:

Available_Time_Period:

Time_Period_Information:

Single_Date/Time:

Calendar_Date:

Time_of_Day:

Multiple_Dates/Times:

Single_Date/Time:

Calendar_Date:

Time_of_Day:

Range_of_Dates/Times:

Beginning_Date:

Beginning_Time:

Ending_Date:

Ending_Time:

Metadata_Reference_Information:

Metadata_Date:

Metadata_Review_Date:

Metadata_Future_Review_Date:

Metadata_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person:

Contact_Organization:

Contact_Organization_Primary:

Contact_Organization:

Contact_Person:

Contact_Position:

Contact_Address:

Address_Type:

Address:
3E-16 Existing Vegetation Classification & Mapping Technical Guide

City:

State_or_Province:

Postal_Code:

Country:

Contact_Voice_Telephone:

Contact_TDD/TTY_Telephone:

Contact_Facsimile_Telephone:

Contact_Electronic_Mail_Address:

Hours_of_Service:

Contact_Instructions:

Metadata_Standard_Name:

Metadata_Standard_Version:

Metadata_Time_Convention:

Metadata_Access_Constraints:

Metadata_Use_Constraints:

Metadata_Security_Information:

Metadata_Security_Classification_System:

Metadata_Security_Classification:

Metadata_Security_Handling_Description:

Metadata_Extensions:

Online_Linkage:

Profile_Name:
Existing Vegetation Classification & Mapping Technical Guide 3F-1

Appendix 3F. 

Existing Vegetation Database Structure

The Existing Vegetation National GIS Standards by Map Level table was developed by

Ralph Warbington, U.S. Department of Agriculture, Forest Service, Pacific Southwest

Region, and can be used to identify where vegetation physiognomic class and subclasses

are likely to intersect land use land cover classes, as indicated by an “x” in the intersecting cell. Cells remaining blank are those where the two classifications do not overlap;

definitions are mutually exclusive for both classification systems. For example, consider

water. Water is defined as open water and will not overlap with any vegetated class.

However, a wetland is defined as having both water and vegetation, and overlaps with

many vegetation physiognomic classes.

For Existing Vegetation GIS Layer Descriptions for National, Broad, Mid and Base

Levels, visit http://www.fs.fed.us/emc/rig/index3.htm.

For Reference Tables and Definitions, visit http://www.fs.fed.us/emc/rig/index2.htm.

Existing Vegetation National GIS Standards by Map Level

Item Base Level Mid Level Broad Level National Level

Ecoregion Levels

Domain R R R R

Division R R R R

Province R R R O

Section R R O O

Sub-section R R O O

Land Use and Cover Categories

USGS Anderson 1 R R R R

USGS Anderson 2 (optional core) O O O O

NVC Physiognomic Levels

Division R R R R

Order R R R R

Class R R R R

Subclass R R1 O O

R = required. 

O = optional. 

1 Required if NVC Order is Tree or Shrub Dominated; optional for other Vegetated Orders.
3F-2 Existing Vegetation Classification & Mapping Technical Guide

R = required. 

O = optional. 

N/A = not applicable.

2 If NVC order is Tree Dominated.

3 If NVC order is Shrub or Herbaceous Dominated.

4 Required regardless of aggregation type; used to assign all upper levels of NVC Physiognomic and National Cover Types.

5 If NVC order is Shrub Dominated.

6 Required only if the Aggregation Type is a group or complex.

7 Optional; use if the Aggregation Type is a group or complex and is needed to describe vegetation within any 

particular map unit.

Floristic Levels and Attributes

Broad and National Level Cover Types

Total Vegetative CFA Class O O O O

SAF Cover Type R2 R2 R2 O

SRM Cover Type R3 R3 R3 O

Mid and Base Levels

Vegetation Map Unit Description

Aggregation Type 

(homogeneous, group, or complex) R R N/A N/A

Most Abundant Type 4 4

Regional Dominance Type 1 R R O N/A

Dominance Type Reference 1 R R O N/A

NVC Alliance 1 R O N/A N/A

NVC Association 1 (optional core) O N/A N/A N/A

Tree CFA Class 1 R2 R2 O O

Tree Diameter Class 1 R2 R O N/A

Shrub CFA Class 1 (optional core) 05 O O N/A

Second Most Abundant Type 6 6

Regional Dominance Type 2 R R N/A N/A

NVC Alliance 2 R O N/A N/A

NVC Association 2 (optional core) O N/A N/A N/A

Tree CFA Class 2 O O N/A N/A

Tree Diameter Class 2 O O N/A N/A

Shrub CFA Class 2 (optional core) O O N/A N/A

Third Most Abundant Type 7 7

Regional Dominance Type 3 O O N/A N/A

NVC Alliance 3 O O N/A N/A

NVC Association 3 (optional core) O O N/A N/A

Tree CFA Class 3 O O N/A N/A

Tree Diameter Class 3 O O N/A N/A

Shrub CFA Class 3 (optional core) O O N/A N/A

Metadata

Data Source R R R R

Source Date R R R R

Map Update Cause R R O O

Created By R R R R

Created Date R R R R

Created In Instance R R R R

Modified By R R O O

Modified Date R R O O

Modified In Instance R R O O

Item Base Level Mid Level Broad Level National Level

Existing Vegetation National GIS Standards by Map Level (continued)
Existing Vegetation Classification & Mapping Technical Guide 3G-1

Appendix 3G. 

Comparison of Anderson Land Use Classes with

Physiognomic Class and Subclass

Use the following table (developed by Ralph Warbington, USDA Forest Service, Pacific

Southwest Region) to identify where vegetation physiognomic class and subclasses are

likely to intersect land use land cover classes indicated by an x in the intersecting cell.

Blank cells are those where the two classifications do not overlap; definitions are mutually

exclusive for both classification systems. 

For example, consider water. Water is defined as open water and will not overlap with

any vegetated class. A wetland, however, defined as having water and vegetation, overlaps

with many vegetation physiognomic classes.
3G-2 Existing Vegetation Classification & Mapping Technical Guide

Relationship between 

Anderson 1 Land Cover Urban

Land Use Classification or Agricultural Range Forest Barren Tundra Perennial

and FGDC Physiognomic built-up land land land Water Wetland land snow

Class and Subclass land or ice

Class Subclass 

code code 1 2 3 4 5 6 7 8 9

Closed tree canopy 

Evergreen TC EV x x x x

Deciduous TC DE x x x x

Mixed TC MX x x x x

Open tree canopy 

Evergreen TO EV x x x x

Deciduous TO DE x x x x

Mixed TO MX x x x x

Sparse tree canopy 

Evergreen TS EV x x x x

Deciduous TS DE x x x x

Mixed TS MX x x x x

Shrubland

Evergreen ST EV x x x x x

Deciduous ST DE x x x x x

Mixed ST MX x x x x x

Dwarf shrubland 

Evergreen SD EV x x x x x

Deciduous SD DE x x x x x

Mixed SD MX x x x x x

Herbaceous—shrub steppe 

Perennial grass HS PG x x x x

Perennial forb HS PF x x x x

Annuals HS AN x x x x

Hydromorphic HS HV x x x x

Herbaceous grassland

Perennial grass HE PG x x x x

Perennial forb HE PF x x x x

Annuals HE AN x x x x

HydromorphicHE HV x x x

Nonvascular 

Bryophyte NV BR x x

Lichen NV LI x x

Alga NV AL x

Sparsely vegetated

Rock SV RC x

Boulders SV BG x

Unconsolidated material SV UM x x

Urban and built-up SV UB x

Nonvegetated XX XX x x x x