USDA Forest Service

Forest Inventory and Analysis National Program


Forest Inventory & Analysis
National Office
U.S. Forest Service
1400 Independence Ave., SW
Washington, D.C. 20250-0003

(703) 605-4177

United States Department of Agriculture Forest Service.

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Program Features



[Photographs] Historic pictures of FIA employees collecting samples on hillside; and another with man holding FIA plot marker.  Two other pictures of FIA employees; one with man collecting samples and another with woman measuring tree's diameter.

Basic Forest Inventory:

Phase 1 is a remote sensing phase aimed at classifying the land into forest and non-forest and taking spatial measurements such as fragmentation, urbanization, and distance variables. This phase has historically been done using aerial photography, but is changing to a system based on satellite imagery.

Phase 2 consists of a set of field sample locations distributed across the landscape with approximately one sample location (FIA plot) every 6,000 acres. Forested sample locations are visited by field crews who collect a variety of forest ecosystem data. Non forest locations are also visited as necessary to quantify rates of land use change.


Forest Health Indicators:

Phase 3 consists of a subset of the phase two plots (approximately 1 every 96,000 acres) which are visited during the growing season in order to collect an extended suite of ecological data including full vegetation inventory, tree and crown condition, soil data, lichen diversity, coarse woody debris, and ozone damage.


Timber Products Output Studies:

FIA conducts Timber Products Output (TPO) studies to estimate industrial and non-industrial uses of roundwood in a state. To estimate industrial uses of roundwood, all primary wood-using mills in a state are canvassed periodically.


National Woodland Owner Survey (NWOS)

To learn more about the National Woodland Owner Survey please visit


FIA Contributions to National and Global Reporting:
The FIA program is the primary official source of authoritative information to a number of national and global assessments, reports, and statistics on the status, conditions and trends of the U.S. forests and the services they provide.


Forest Resources of the U.S.:
Every five years, FIA produces The Forest Resources of the United States, a report presenting the information on the status, condition, and trends in the Nation's forests. These reports, mandated by the Agriculture Research, Extension and Education Reform Act of 1998 (Farm Bill), include "an analysis of present and anticipated uses, demand for, and supply of the renewable resources, with consideration of the international resource situation, and an emphasis of pertinent supply, demand and price relationships trends."


Urban FIA:
Urban trees and natural spaces are critical to human health and well-being. The more we know about the trees in our cities and towns the better we can nurture them and sustain their benefits. Generally speaking we seem to know quite a bit about traditional rural forests, but what do we know about forests in developed areas? What do they look like? How are they managed? How are they changing? These are many of the questions that the USDA Forest Service's Forest Inventory & Analysis (FIA) Urban program sets out to explore.

Given the importance of urban lands, Urban FIA has three parallel components:
   1) Urban Forest Inventory & Analysis
   2) Urban National Landowner Survey (UNLS)
   3) Urban Wood Flows


Carbon Estimation:
Carbon estimation is an increasingly important topic on a global platform. Visitors can find standard estimates by domains of interest, emerging research and associated highlights, documentation, important links, and general background regarding carbon estimation in the FIA program.



Additional information is available in the FIA Online Library.


USDA Forest Service
Last Modified: July 22, 2022

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