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Criterion 7 Indicator 61
Scope, Frequency, and Statistical Reliability of Forest Inventories, Assessments, Monitoring, and Other Relevant Information
This indicator assumes that better quality forest information increases the likelihood that forests will be managed on a sustainable basis. Without adequate data, trends cannot be detected nor impacts estimated.

Two major programs provide statistically reliable inventory and health monitoring data for the forests of Oregon. These programs are described below.
Forest Health Monitoring (FHM) Program
The FHM is a national program established in 1990 by several federal and state agencies. Its mission is to monitor, make assessments, and report on the long-term status, changes, and trends in the health of the nation’s forest ecosystems. The FHM is managed by the U.S. Forest Service, in cooperation with the Oregon Department of Forestry, the U.S. Environmental Protection Agency, and the Bureau of Land Management. FHM is comprised of four interrelated activities, as described below.
Annual monitoring — This part of the program covers all forest lands regardless of ownership. The program has established a series of plots on which environmental indicator measurements are made annually. Also, the program has a survey component that surveys insects, diseases, and other stresses on forests. The purpose of annual monitoring is to collect information on the condition of forest ecosystems, estimate current conditions, and detect changes in those conditions over time.
The annual monitoring uses a sampling design based on a hexagonal grid, with grid centers seventeen miles apart. Four plots, each one approximately sixty feet in diameter, are located around the center of each hexagonal grid. Forested plots are measured on a four-year cycle. When the program started in Oregon, measurements were taken on all plots. In following years, a specified one-fourth of the total plots were measured each year. In addition, one-third of the plots measured in the previous year were measured. This protocol continues to be followed.
Evaluation monitoring — This part of the program examines the extent, severity, and probable causes of undesirable changes in forest health that have been identified by the annual monitoring activities. It then proposes management alternatives and follow-up research needs.
Intensive site ecosystem monitoring — This part of the program monitors a set of key indicators in depth, in order to collect detailed information on key components and processes in forest ecosystems.
Research on monitoring techniques — This part of the program is basic research specifically designed to improve the other three monitoring activities.
FHM data and reports will be available on the World Wide Web (WWW). Data quality, statistical reliability, and availability are guided by the following goals: assure that the data are of the highest quality possible, maintain records of changes to the data, assure that FHM scientists have access to the data as soon as possible, and make the data available to users both within the project and outside the FHM group.
Forest Inventory and Analysis Program
The Forest Inventory and Analysis program, initially known as the Forest Survey, was conceived many years ago when Congress acknowledged the need for information about the supply and condition of the nation’s natural resources. The Organic Act of 1897, which established the national forests, included provisions for the inventory and management of these lands. Later, the Forestry Research Act (McSweeney-McNary) of 1928 directed the Secretary of Agriculture to: "…make and keep current a comprehensive inventory and analysis of the present and prospective conditions of and requirements for the renewable resources of the forest and rangelands of the United States…" The Forest and Rangeland Renewable Resources Research Act of 1978, which replaced the earlier Forestry Research legislation, repeated the amendment contained in the earlier law.
Forest Inventory and Analysis (FIA) is an ongoing program. Its objective is to periodically determine the extent, condition, and volume of timber, growth, and depletions of the nation’s forest land. This kind of up-to-date information is essential to frame realistic forest policies and programs. The U.S. Forest Service regional experiment stations conduct these inventories and publish summary reports for individual states. Forest inventories in Oregon are done by the Pacific Northwest Research Station (PNW) through the Pacific Resource
Inventory, Monitoring, and Evaluation Program (PRIME).
Every five years, the U.S. Forest Service assesses the nation’s resources. PRIME’s resource data is combined with similar data from other U.S. Forest Service research stations and the national forest system. The combined data is the primary source of information for this extensive analysis. Changes in land area, ownership, and resource condition are studied. Analysts use PRIME data to identify and interpret trends in the quantity and quality of natural resources.
PRIME maintains a permanent grid of field plots across the Pacific Coast states. After a plot is established on the ground, field crews return once every ten years to re-measure trees, understory vegetation, and other resource attributes. Data gathered on these plots is combined with data collected by analyzing aerial photographs, satellite imagery, and map layers within Geographic Information Systems (GIS).
PRIME manages a comprehensive database that contains both current and past resources data. This database is available to the public and serves as a primary source of forest and range information.
When a field crew visits a plot, measurements are taken on:
  • trees (including growth, health, mortality, and harvest)
  • snags, standing dead — size, use, and decay
  • understory vegetation, shrub, herb, and grass species
  • coarse woody debris, down dead wood
  • crown cover
  • stand history
  • soils, aspect, slope, land forms
PRIME regularly summarizes, analyzes, and publishes resource materials, which are available to the public. Examples of data in reports include:
  • forest area by forest type and stand size
  • timber volume by species and diameter class
  • changes in area and volume over time
  • tree growth and mortality
  • biomass estimates
Forest Inventory and Analysis data is only collected on non-federal forest lands. To provide a complete view of forest lands, FIA data must be combined with other inventory data taken on U.S. Forest Service and BLM lands.
Inventory data are available through the National FIA Data Base Retrieval System.