Filename: SOIL_FLR.DBF

About the Forest Health Monitoring (FHM) Program:
The FHM program is managed by the USDA Forest Service (FS) in
cooperation with other program participants. Funding comes largely from
the FS and the U.S. Environmental Protection Agency.  Other participants
include State Forestry and Agriculture agencies, the USDI Bureau of Land
Management, the Tennessee Valley Authority, the USDA Natural Resources
Conservation Service, and several universities. The National Association
of State Foresters provides essential program support, guidance, and
assistance. Detection Monitoring, the most extensive of FHM's three
monitoring activities, is designed to provide data to determine baseline
or current conditions of forest ecosystems, and to detect changes and
trends over time. This information is analyzed to determine if detected
changes are anticipated, and if those changes indicate improving forest
health or are cause for concern, warranting additional evaluation.
Detection Monitoring covers all forested land and has two components:
(1) the on-frame component, which is measurements made on the FHM
network of permanent plots; and (2) the off-frame component, which is
forest surveys made off of the FHM plot network and includes forest
insect, disease, and other stressor effects. (References: The Forest
Health Monitoring National Brochure, and the FHM Fact Sheet Series.
Available at the Forest Health Monitoring National Office, P.O. Box
12254, Research Triangle Park, NC, 27709)

Coverage:
FHM uses the EMAP sampling grid, which is formed from a triangular grid
of sampling points. The FHM ground plots are approximately 1-hectare in
size and contain 4 subplots approximately 1/60 hectare in size. Ground
plots are approximately 27 km apart. (Reference: Stevens, D.L. 1994.
Implementation of a national monitoring program. J. Environ. Manage.
42:1-29.)

About the Index/Measurements:
The soil organic (O) horizon is used as an estimation of forest floor
thickness. The forest floor is considered to be an equilibrium layer of
organic materials deposited by plants on the mineral soil surface.

Complete information about the measurements can be found in the Forest
Health Montioring Field Methods Guide (Tallent-Halsell, N. (editor).
1994. Forest Health Monitoring 1994 Field Methods Guide. EPA/620/R-94/027. U.S. Environmental Protection Agency, Environmental Monitoring
Systems Laboratory, Las Vegas, NV.)

Definition of Data Set Variables (in the order they appear in the data
set):

HEX_ID -  the unique 7-digit code assigned to each 40 km2 hexagon.

O_THICK - thickness (cm) of the organic soil horizon.