USDA Forest Service Resource Information Group

Existing Vegetation Classification, Mapping, & Inventory Technical Guide (GTR-WO-90)

The Existing Vegetation Classification, Mapping, and Inventory Technical Guide Version 2.0 (GTR WO-90) is the latest in a series of published guides for resource professionals and managers that provide scientifically credible approaches to sampling, data collection, and data analysis. This technical guide establishes Forest Service guidelines and procedures for existing vegetation classification, mapping, and inventory activities to improve the consistency and utility of existing vegetation products.

The accompanying Existing Vegetation Data Dictionary describes feature classes and attribute fields for mapping existing vegetation at four hierarchical levels: National, Broad, Mid, and Base that support various business functions of the agency. Attribute fields capture the key components of vegetation mapping including physiognomy (outward appearance of the dominant plants); floristic composition (classification of plant communities); and structure (pattern of growth, such as size, abundance, or coverage).

Awareness and Training Material

Agency Leadership

Awareness material for agency leaders (e.g., line officers and program mangers) that should understand the general approach and level of effort to successfully complete vegetation classification, mapping, and/or inventory projects will be provided when available.

Vegetation Project Managers

Awareness material for project team members (e.g., vegetation ecologists, inventory specialists, and remote sensing/GIS specialists) that should understand the processes used to classify, map and integrate inventories of existing vegetation will be provided when available.


Journey-level resource professionals need to understand best practices and have technical competencies to accomplish work associated with classification, mapping, and inventory processes consistent with Existing Vegetation Technical Guide (EVTG) guidance. See the following three sections for resources relating to the processes of classification, mapping, and inventory.


Vegetation classification is the grouping of similar entities into named types or classes based on shared characteristics. Classification answers the question, “What is it?” and using a classification system helps us understand vegetation community ecology, placement and function. Regional ecologists have responsibility for coordinating these activities within their Regions, thus, for additional information regarding classification processes; please contact your Regional Ecologist or Classification Specialist.


Vegetation mapping is the process of delineating the geographic distribution, extent, and landscape patternsof vegetation types and structural characteristics. Mapping answers the question, “Where is it?” Vegetation maps delineate the geographic distribution, extent, and landscape patterns of vegetation types and/or structural characteristics in an area of interest. Consistent mapping of vegetation needs to be based on appropriate classification systems consistent with the objectives of the map. Maps often form the analytical basis for spatially depicting inventory information.

The following are links to existing vegetation mapping training modules. Additional training modules will be provided when available.


Vegetation inventory quantifies the amount, composition, and condition of vegetation types with known statistical precision. Inventory answers the question, “How much is there?” To be most useful, inventories need to incorporate a statistically valid sample design, be non-biased, and provide both population estimates and an indication of their reliability. The Design and Analysis Toolkit for Inventory and Monitoring (DATIM) project provides tools to assist national forests and grasslands and other users in determining objectives, questions, and metrics for monitoring plans, and enable users to analyze vegetation data to derive estimates of current conditions and trends on the Forest and surrounding landscapes. Here is a link to the DATIM webpage that provides access to DATIM tools, user guides, training module, and other information.

Protocol Implementation

In 2014, the Associate Deputy Chiefs of the National Forest System, Research and Development, and State and Private Forestry chartered the Existing Vegetation Technical Guide Implementation Management Team (IMT). The IMT provides technical and policy review of products being developed, monitors project progress, and provides policy recommendations and resolves technical and coordination issues identified by Technical Working Groups. The IMT chartered three Technical Working Groups to address specific issues, develop recommendations, and draft technical materials. The following are links to current charters of the IMT and three Technical Working Groups.

Brief History of the Existing Vegetation Technical Guide

The Existing Vegetation Classification and Mapping Technical Guide (Version 1.0) was published in 2005. After 2005, the Federal Geographic Data Committee (FGDC) adopted vegetation classification standards that were not reflected in the original Technical Guide. Consistent procedures for compliance with FGDC standards are essential to facilitate landscape-scale coordination across administrative units and with our conservation partners. To address those needs, agency vegetation classification, mapping and inventory specialists met to discuss the impacts of those changes and recommended a series of action items to improve the guide. These recommendations formed the basis for a project proposal containing two phases which was approved by the Information Resources Board (IRB) and sponsored the by the Sustainable Landscape Management Board of Directors (SLMBOD) in 2010 (see Existing Vegetation Technical Guide Revision Charter (June 16, 2010) (PDF, 162 KB)).

Phase 1 of the Existing Vegetation Classification and Mapping Technical Guide revision effort was completed in 2011 and ensured consistency with 2008 FGDC standards and FSM 1940 revisions (see Revised Existing Vegetation Technical Guide, Version 1.1 (PDF, 9.2 MB)). Soon after, a Business Requirements Analysis was conducted as part of phase 2 of the revision effort. This document identifies management requirements established by law, regulation and policy; discusses relationships between decision-making scales and data needs; provides an overview of management questions; and defines the framework and scope for the Technical Guide revision effort (see Business Requirements Analysis (PDF, 1.6 MB)).

Related Publications

This section contains peer-reviewed and other relevant documents that are directly related to and from the perspective of the Existing Vegetation Technical Guide.

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