Lab 1: Basal Area Comparisons for Hardwoods and Softwoods in Varying Soil Drainage
Classes
Heiberg Forest, Tully, NY
James Werner, Eric North, Andrew Testo
9/15/05
Abstract
Seven plots were measured in Heiberg Forest for basal area and species
composition. The basal area of the species was compared to the soil drainage class at
each point. Results show that hardwoods were dominant in all plots but basal area of
softwoods increased from none to 50 as drainage class went from moderately well
drained to poorly drained.
Introduction
One major factor that determines how well certain tree species grow on a site is
the soil drainage class. When soil drainage is poor, oxygen levels in the soil are low, and
therefore limits plat respiration. Some species are better adapted to compete in poorly
drained soils. By measuring the density of growth of certain species within an identified
drainage class, a trend can be determined for their site preference.
In this experiment we measured basal area to compare the density of hardwood
and softwood trees at each plot. Hardwood species are expected to dominate the well
drained soils, while being co dominant in poorly drained soils.
Methods
Seven plots were measured with a BAF 10 prism to determine their basal area.
All trees counted were identified to species. This was done on a South facing aspect with
a slope ranging from 5-25%.
Results
The numbers show that there is little to no basal area for softwoods in the well
drained soils of plots 1 to 4. As soil drainage becomes poorer from plots 4 to 7, basal area
for softwoods increases. This agrees with our original hypothesis.
Hardwoods
Plot
1
2
3
4
5
6
7
1
2
3
4
5
6
7
RM
3
2
4
HM
10
5
3
4
1
1
-
Softwoods
HE
NS
1
2
1
3
3
5
-
Total basal area per
plot
B.A.
1
130
2
120
3
110
4
120
5
110
6
80
7
150
BE
3
4
2
6
BC
3
7
4
2
3
-
Basal
Area
130
120
100
90
80
50
100
Basal Area
10
30
30
30
50
Drainage class
Moderate/well
Moderate/well
Moderate/well
Moderate/well
Poorly
Poorly
Very Poorly
Plot
1
2
3
4
5
6
7
Hardwood species
7
Plot
6
BC
BE
HM
RM
5
4
3
2
1
0
2
4
6
8
10
12
Number of trees
Softwood Species
7
6
Plot
5
NS
HE
4
3
2
1
0
1
2
3
Number of trees
4
5
6
Species Composition
7
6
Hardwoods RM
Hardwoods HM
Hardwoods BE
Hardwoods BC
Softwoods HE
Softwoods NS
Plot
5
4
3
2
1
0
2
4
6
8
10
12
14
16
Number of trees
Hardwood Vs. Softwood basal area
7
6
Plot
5
SW
HW
4
3
2
1
0
20
40
60
80
Total Basal area
100
120
140
160
Basal area Precentages
7
6
Plot
5
SW
HW
4
3
2
1
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Percent
Discussion
From our results, we can conclude that there is a correlation between soil drainage
and species composition and density. The first two graphs illustrate the change in the
numbers of each species by plot. In the well drained soils the dominant species was
Sugar Maple (Acer saccharum), while in the poorly drained soils it was more scarce.
Beech becomes the dominant species in the poorly drained soils, but there is an
increasing number of Eastern Hemlock (Tsuga canadensis). Because E. Hemlock was
seen only in the poorly drained soils, it can be concluded that it is better suited to
compete in that environment. The last two graphs show that hardwoods do have a greater
amount of basal area in the poorly drained soils however this value was approximately
35% higher in the better drained soils. Given an adequate amount of time, the hemlocks
may dominate over beech and other species given its longevity compared to the other
species and its ability to compete in poorly drained soil.