National Park Service

Northeast Temperate Network (NETN)

forest health


Forest health describes the condition and diversity of trees and other vegetation, as well as the status of important forest processes like nutrient cycling. Healthy forests provide suitable habitat for native animals and plants, purify air and water, and help regulate the climate. Forests also provide valuable recreational opportunities and important natural resources for fuel, lumber, and paper.

Importance & Issues

Forest surrounding AT in Shenendoah NPThe Appalachian Trail (A.T.) passes through some of the largest and least fragmented forest blocks remaining in the eastern US, and these forests provide important habitat for understory vegetation and wildlife including many rare species. Air pollution, in the form of ground-level ozone and acid rain, is substantial across much of the A.T. corridor and is thought to be negatively impacting forest health. Destructive insects and diseases from other parts of the world are causing mortality to some forest trees within the A.T. corridor, including American beech, hemlock, Fraser fir, butternut, and flowering dogwood.

Monitoring forest health along the A.T. will help resource managers understand the overall condition of eastern forests, including the prevalence of forest pests and diseases, as well as the impact of air pollution and other stresses. Due to its length and position on the landscape, the A.T. may be particularly useful for monitoring environmental change. For example, acid rain is currently deposited along the entire length of the trail, and is known to cause increased mortality in red spruce and sugar maple trees. Likewise, climate change is likely to result in even more dramatic shifts to forest communities. As climate change alters temperature and rainfall patterns, the dominant maple-beech forests of the north may gradually shift to a more southern oak-hickory forest, and vegetation communities may shift upwards along elevational gradients. Detecting such changes can be accomplished by monitoring ecotones, or the transitional zones between adjacent communities.  Similarly, as the land surrounding the trail becomes more fragmented by development and other landscape changes, forests may lose species that require interior forest habitat and may acquire weedy generalist species that are already prevalent across the landscape.

Forest Health monitoring is already occurring throughout the United States. The US Forest Service (USFS) Forest Inventory and Analysis (FIA) program has been monitoring forest trees across the nation since 1930.  This program collects, analyzes and reports information describing status and trends in existing forest cover, ownership, management and harvest, and tree composition. In the 1990s, this program expanded to include forest health measures such as tree growth, understory diversity, the quality of soil supporting forest vegetation, the quantity of dead wood present, and, in some areas, the impacts of air pollution on vegetation and lichen communities. Although the FIA program is designed to assess and report across large regions that are not specific to the A.T., this program can still provide insight into forest health status and trend for the broader Appalachian Trail region by stratifying the available FIA data by ecoregion or state.

Monitoring Objective

Determine the status and trend in soil Ca:Al and C:N ratios to assess the extent of base cation depletion, The National Park Service seeks to establish an Appalachian Trail focused Forest Health initiative that relies on existing programs and reporting capabilities; and, to a lesser extent, on the development of new protocols to guide the collection and management of new data by citizen scientists. The initiative is envisioned to serve several broad purposes: 1) to guide management of Appalachian Trail forest resources; 2) to provide advance warning of large-scale, landscape level concerns such as insect mortality and climate driven change; 3) to direct more intensive Forest Health investigations; and, 4) to give the public limited access to available forest health resources.


  1. Analyze available FIA/FHM data. FIA data aggregated to Bailey (1983) ecoregions and / or sub-ecoregion level, counties, or states may be appropriate.
  2. Supplement existing FIA/FHM data if necessary.
  3. Identify and coordinate with complementary A.T. MEGA-Transect projects.
  4. Develop an ecotone monitoring system using FIA compatible plots.
  5. Identify key Forest Health contacts and existing data sets along the AT from:
    1. National Parks
    2. Inventory & Monitoring Program Networks
    3. National Forests
    4. State Agencies
    5. Long-Term Ecological Research Stations
    6. Non-Profit nd Other
  6. Develop a Citizen Science appropriate monitoring protocol to collect supplementary data.

Priority Questions

  1. What is the status and trend in distribution of land by landcover, landuse and ownership categories?
    1. total land
    2. forest area
      1. timberland
      2. reserved forest
      3. other forest
    3. land class
    4. public
    5. industry
    6. private
  2. Is the location, extent and composition of high-elevation habitat changing?
  3. What is the distribution of forest land by harvest intensity?
  4. What is the status and trend in extent, structure, composition and function of “dominant” forest ecosystems? Key metrics include:
    1. forest ecosystem area
    2. patch size distribution
    3. tree composition, mortality and regeneration
    4. age/structural class distribution
    5. understory composition
    6. soil chemistry
    7. canopy closure
  5. Are phenological patterns of key species changing, what are the specific climatic drivers involved and how is that affecting those species and inter-specific relationships? Key species include:
    1. canopy trees
    2. invasive insect pests/pathogens of forest trees
    3. key invasive exotic species
    4. rare plants
    5. mountain and breeding birds et al.
  6. What is the status and trend in habitat availability for key species (mountain birds, breeding birds, selected fish, selected rare plants), and can we make future predictions based on climate-driven and other anthropogenic change?
  7. Are ecotonal zones (tree lines; plant communities; others?) changing (spatially or temporality)?



Last Updated: December 30, 2016 Contact Webmaster