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Ecosystem Indicators (P3)

LichenThe Forest Inventory and Analysis (FIA) program systematically samples forests across space and time to provide a baseline for detecting changes in ecosystem health. The U.S. Forest Service has surveyed indicators of ecosystem health for more than two decades, focusing on key threats such as climate change, invasive species, and air pollution.

Ecosystem Indicator monitoring provides long-term, consistent data from fixed plots that are used to evaluate state and regional forest health issues, as well as contribute to national and international reporting.

Recent Publications



  • Vegetation diversity and structure

    The vegetation indicator (VEG) is an extensive inventory of vascular plants in the forests of the United States. The VEG indicator provides baseline data to assess trends in forest vascular plant species richness and composition, and the relative abundance and spatial distribution of those species, including invasive and introduced species. The VEG indicator is one of several sets of measures collected by the FIA program of the U.S. Department of Agriculture Forest Service to assess forest health. This document describes the sampling design, field data collection methods, primary output objectives, and estimation procedures for summarizing FIA-VEG data.

  • Lichen communities

    The purpose of the lichen community indicator is to use lichen species and communities as biomonitors of change in air quality, climate change, and change in the structure of the forest community. Lichen communities are excellent indicators of air quality, particularly long-term averages of sulfur dioxide concentrations. Lichen communities provide information relevant to several key assessment questions, including those concerning the contamination of natural resources, biodiversity, and sustainability of timber production.

  • Ozone injury

    Air pollutants, such as ground-level ozone, are known to interact with forest ecosystems. Ozone pollution has been shown to adversely effect tree growth and alter tree succession, species composition, and pest interactions. We know that ozone causes direct foliar injury to many species, and we can use this visible response to detect and monitor ozone stress in the forest environment.

    Ozone bioindicator plants are used to monitor changes in air quality across a region, and to assess the relationship between ozone air quality and indicators of forest condition (e.g., growth increment and dieback). A useful bioindicator plant may be a tree, a woody shrub, or a nonwoody herb species. The essential characteristic is that the species respond to ambient levels of ozone pollution with distinct visible foliar symptoms that are easy to diagnose, including distinct patterns of coloration often associated with accelerated senescence.

  • Down woody material

    Down woody materials (DWM) are important components of forest ecosystems. DWM is dead material on the ground in various stages of decay. Wildlife biologists, ecologists, mycologists, foresters, and fuels specialists are some of the people interested in DWM because it helps describe the:

    • Quality and status of wildlife habitats
    • Structural diversity within a forest
    • Fuel loading and fire behavior
    • Carbon sequestration - the amount of carbon tied up in dead wood
    • Storage and cycling of nutrients and water - important for site productivity
  • Tree crown condition

    Crown evaluations are quantitative assessments of current tree conditions that provide an integrated measure of site conditions, stand density, and influence of ecosystem stressors. Healthy crowns have greater potential for carbon fixation, nutrient storage, and long-term survival and reproduction.

    Crown measurements include uncompacted live crown ratio, diameter, density, transparency, dieback, and canopy position. Measurements can be used alone or combined to estimate crown volume or surface area. Crown conditions are also recorded for saplings, which are then categorized into three broad vigor classes.

  • Tree damages

    Inventorying damages to trees on Forest Inventory and Analysis (FIA) plots provides valuable information for assessing forest health at both the stand and landscape scales. Knowing the extent of tree damages helps land managers and researchers predict tree growth and survival and track long-term effects of some tree diseases and insects.

    Damage agents recorded by FIA field crews include bark beetles, defoliators, root disease, blister rust, sudden oak death, dwarf mistletoe, and rotten / missing / rough cull. The amount of cull and physical form defects (e.g. crooks, forks) is important for estimating volume, biomass, and carbon associated with sound, rotten, or missing portions of individual trees.

  • Forest soils

    The soil resource is a primary component of all forested ecosystems, and environmental stressors that interfere with natural soil function have the potential to influence site productivity, species composition, and hydrology. Soil physical and chemical properties are assessed on forested plots.

    Physical properties of the soil, such as compaction and erosion, play a key role in plant nutrition and hydrology, especially surface and ground water flow. Soil structure and texture are assessed to estimate availability of nutrients and water to plants.

    Fertility and potential productivity of forested stands are assessed from soil chemistry. Properties such as plant nutrient status, organic matter, and acidification are key indicators of forest health. Soil organic matter is also a key component of forest carbon sequestration.

  • Invasive species

    Nonnative plants affect the composition and function of natural and managed ecosystems. RMA researchers are working to provide more comprehensive information on the abundance, distribution, and impact of nonnative invasive species.

    A field guide has been produced for identifying nonnative invasive plants of Pacific coast forests. This publication provides a prioritized short list of the nonnative invasive plants having the greatest impact on forested lands in the Pacific Coast States (California, Oregon, and Washington).

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