Forest Health Monitoring Soil Measurements
Important Initial Findings
C.J. Palmer and B.L. Conkling
University of Nevada, Las Vegas North Carolina State University
palmerc@nevada.edu
bconkling@fs.fed.us
MATERIALS AND METHODS
Soil compaction: Field crews identify the presence and extent of soil
compaction. After estimating the extent of compaction on a subplot,
crews record evidences of compaction and the type of compaction.
Soil erosion: Measurements taken are used to estimate soil erosion
potential with the Revised Universal Soil Loss Equation. These include
% cover estimates (bare soil, litter cover and depth, plant cover and
height), slope and slope length.
Soil chemistry: FHM crews collect soil samples from three locations on
FHM plots. Forest floor samples are obtained at one of the sampling
locations by removing a 30 cm diameter circle. Litter samples are
analyzed for total C and N. Beginning in 2000, soil samples have been
collected from the 0-10 and 10-20 cm depths using bulk density corers.
Soil samples are analyzed for total C and N, soil pH (H2O and 0.01M
CaCl2), Bray1 P, and exchangeable cations.
ABSTRACT
The national Forest Health Monitoring program provides
annual evaluations of the ecological condition of forests for
the United States. Approximately one thousand plots are
visited each year on a five year remeasurement cycle.
Measurements designed to assess important issues related to
soils were added in 1998. Observational measurements
provide for a assessment of erosion potential and evidences
of soil compaction. Soil samples are collected to analyze
for soil nutrients, carbon and acidity. Soil erosion potential
was generally low with the exception of a few recently
disturbed sites. In contrast, evidence of soil compaction
was found to be widespread. Forests showing symptoms of
poor health were often found on the more nutrient deficient
soils. Soil acidity reflected expected patterns related to soil
genesis and acidic deposition. Bulk density measurements
have recently been added to allow for an assessment of
changes in soil carbon pools.
Figure 1
RESULTS
Soil compaction The most common evidence of
compaction by crews was an increase in the density of the
soil in the compacted area when compared to adjacent
non-compacted areas. The most common type of
compaction identified by crews was compacted trails.
Figure 3 presents the percentage of subplots with
compacted areas as well as compacted areas exceeding
the 15% threshold. It is apparent that the West Coast
region identified soil compaction on a larger percentage
of their plots than the other regions. When compaction
occurred, it often exceeded a 15% threshold.
INTRODUCTION
Figure 2
Soil Compaction - 1999
Soil erosion is generally not a problem on forest plots
unless recent disturbance has resulted in bare soil being
left exposed. (Figure 4).
Maple/Beech/Birch Forest Types
16
14
12
% of Subplots with Compacted
Areas
% Subplots with >15%
Compacted Area
10
8
6
4
2
% dieback (plot level ave.)
18
20
15
North
OBJECTIVES
To provide an overview of initial findings from the program
To encourage the use and distribution of FHM soils data
and information
South
Interior
West
West Coast
Average
Hardwood
Dieback
10
5
0
Figure 3
0
3
4
5
6
7
Figure 5
salt pH
Overall
8
Erosion Alabama Plots
45.00
50
30.00
40
% damage
35.00
25.00
20.00
30
Percent Damage
to Softwoods
20
10
15.00
0
10.00
0
5.00
5
10
15
20
Organic C% in A Horizon
34
31
28
25
22
19
16
13
10
7
0.00
4
tons/acre
Soil Chemistry: Figures 1 & 2 provide some preliminary
examples of the regional nature of results provided by the
FHM program. Soil chemistry can be a contributing
factor to forest health. Forests of the maple/beech/birch
group have higher levels of dieback at lower pH’s (fig.
5). Forests of the loblolly/shortleaf pine group are more
likely to show symptoms of of tree damage at lower
levels of soil organic matter (fig . 6)
Loblolly/Shortleaf Pine Group
40.00
1
The Forest Health Monitoring (FHM) program has been
established in the United States to address environmental
concerns related to the impacts of air pollution, acid rain,
global climate change, and land management practices on
forest ecosystem health. An important component of the
FHM program is a network of permanent Detection
Monitoring plots used to detect status and trends in the
condition of forests. This year these plots were
incorporated as Phase 3 of the Forest Inventory and
Analysis (FIA) program. The plots are found on ALL forest
lands (public or private) with one plot for each 100,000
acres of forest land. States have the option of intensifying
the network.
Figure 4
Return to FHM Posters Home Page
Figure 6
CONCLUSIONS
The FHM program provides a unique regional and national
view of forest soils and their relationship to forest
conditions.
If you have an interest in the FHM database, please send us
a note.