For 332 – Lab #4
Team Xtreme: Chad Wagner, Jon DeSantis and Steve Woods
October 18, 2005
Abstract
In this lab experiment, Team Xtreme studied a site in Syracuse, NY. The site is an
abandoned stone quarry. This site has progressively older regeneration as the stone
quarry moved on when the stone ran out. The central concept of this lab is succession.
So, Team Xtreme hypothesized that the older the regeneration at the quarry, the greater
the diversity of species would exist. The range of regeneration was from approximately
thirty years old to remaining forest land that was not mined. The hypothesis was proved
true with the exception of the remaining mature forest. Here the canopy limited the
undergrowth and therefore species diversity.
Introduction
Succession is a process of change in species composition and structure with time.
There are two types of succession, primary and secondary. Primary succession is the
initial growth on bare rock or dirt with no existing organic matter. This is the main type
of succession that was studied at the quarry. Only the remaining forest plot had
experienced secondary succession. This plot served as our control. In our experiment
plots were measured and every type of plant species, and number of individuals of that
species were measured. It was found that diversity of species increased with age of
regeneration. Also, as age of regeneration increased, ground cover from grasses and
shrubs increased. It was notable that grasses and shrubs tended to grow only around
where trees, mostly aspens, had established themselves and some organic matter, leaves
mostly, existed. To measure diversity, multiple diversity indexes were used. “A diversity
index is a mathematical measure of species diversity in a community.” Number of species
per plot, number of individuals per species per plot and the Shannon-Wiener Diversity
Index were used. The Shannon-Wiener Diversity Index “is commonly used to
characterize species diversity in a community.” Also, it “accounts for both abundance and
evenness of the species present.” These indices proved our hypothesis.
Citation
Beals, M. "Diversity Indices: Shannon's H and E."
Tiem: The Institute for Environmental Modeling. 2000. 19 Oct. 2005
<http://www.tiem.utk.edu/~gross/bioed/bealsmodules/shannonDI.html>.
Methods
Our experiment took place in an abandoned limestone quarry located on South
campus that was experiencing multiple stages of successional growth. One 10’x10’ plot
was marked at each of the five sites, recording every type of vegetation inhabiting the
inside of the plot. A general description of the site’s terrain and characteristics were also
noted.
Results
Plot one had only two trees and three shrubs, while plot two had six trees and
thirty six shrubs. The third plot had six trees and thirty eight shrubs. At the fourth plot,
the plant growth was more diverse, producing 11 trees and 650 shrubs. Plot 5A had the
same type of growth, having 12 trees and 840 shrubs.
Graph 1
# of Individuals
Number of Trees and Shrubs per Plot
45
40
35
30
25
20
15
10
5
0
# trees
# shrubs
1
2
3
4
Plot #
5A
5B
Plot 5B was a stand of mature hardwoods, creating a dense canopy that prevented shrub
and sapling growth.
In order to understand the diversity of the species at each plot, we had to use
McIntosh’s Species Diversity equation. The results of these calculations can be seen in
Graph 2.
Graph 2
McIntosh Species Diversity per Plot
0.7
McIntosh Species
Diversity
0.6
0.5
0.4
0.3
0.2
0.1
0
1
2
3
4
5A
5B
Plot #
As displayed in the above graph, there is more species diversity as time from
abandonment increases. Diversity decreases at plot 5B due to the conditions of the site.
There is a dense canopy due to the mature overstory.
Discussion
The area this lab took place has been severely disturbed due to past use. By
experimenting on species diversity between consecutive plots within the area, a pattern of
succession can be observed. The predicted outcome of experiment is supported by the
results. As the plots on the transect get closer to the later stages of succession the more
diversity in plant species appears on the site. The only real prominent tree species in the
early successional sites is quaking aspen, Populus tremuloides. Quaking aspen grows on
a variety of soil types; from loamy sands to heavy clays (USDAFS Silvbics of North
America). This species is also quick to pioneer disturbed sites, including sites where there
is bare soil, like the area this study was implemented on (USDAFS Silvbics of North
America). Often when a pioneer species moves in on a disturbed site a wide array of
grasses and shrubs are known to follow. Although many of the grasses’ and shrub’s
genus and species names were not recorded, the presence of them is a good indicator of
the successional stage being observed. As the plots being inventoried moved closer to the
mature forest the more species were being recorded. This continued until a plot was
reached that was located in a mature forest. This plot had only three species on it, with no
shrubs or grasses. Because the trees were mature and well established the canopy over the
site was very dense. This allows for little sunlight to break through and reach the forest
floor, promoting understory growth. The area this lab was located at provides a good
view of the process of succession on a disturbed site.