Nathan Turk, Jose Lopez, Tom Ryan
For 332-lab #4
October 20, 2005
Tree Height as a Function of Successional Stage
Abstract
Succession is a process that affects all the environments in the world, and in
which species composition and structure changes over time. We expect to find a linear
decrease in the amount of trees and heights as you go from the site that was abandoned
the longest ago, site four, to the most recently abandoned site, site one. We expect to find
also that site five, which was never part of the quarries, to have the greatest number of
trees and the greatest variation in tree height of all five sites. In all 5 sites, a 1/4 chain
was measured from the flag that is placed at each site and then with a tape measure or a
clinometer we measure the height of each tree. The height of the trees decreased linearly
from site 4, the oldest site, to site one the youngest site. Also the number of trees at each
site followed a similar pattern with the exception of site three, which had a fewer trees
than site two. The older the site, the greater the height and vertical distribution of
foliage, the greater the tree dbh and growth rate, and the greater the number of trees and
shrubs; however, shrub abundance doesn’t increase with site age the way measurable tree
variables do. Environmental conditions present during primary succession processes
aren’t as favorable for growth as those present at later stages. Steady-state sites (possibly
represented by the abandoned quarry’s wooded site) occur because early-stage species
favorably alter sites for later succesional stages.
Introduction
Succession is a process that affects all the environments in the world, and in
which species composition and structure changes over time. This process is a directional
non-seasonal cumulative change and involves other processes such as colonization,
establishment and extinction (Pidwirny, 2005). Different disturbances cause different
types of succession: primary and secondary. In primary succession, the local
environment starts without organic matter and it is tribe by pioneer species. Primary
succession can be classified into different types depending on the conditions of the
environment. (Succession in dry environments is called xerarch, and on wet, hydrarch.)
The second type of succession is secondary succession, which start with organic material
(Perry, 1994). In this experiment we studied a quarry site which was abandoned and
moved four times to different places during the 20th century, which today all are
abandoned quarries with different successional stages. We also studied an adjacent
wooded area which was never mined, comparing its successional stage to those of
different areas of the quarry. We expected to find that site four, the quarry that was
abandoned the longest ago, would have a greater amount of trees and taller trees in
comparison to sites three, two and one, with one being abandoned most recently. Also,
we expected site five to have the greatest variation in tree height and the greatest number
of trees of all five sites.
Methods
The heights of all trees within a ¼ chain (approximately 16.5 feet) sampling area
were taken at each of the 5 sites within the abandoned quarry at Syracuse University’s
south campus. The flag of each site was used as the center of the ¼ chain sampling area.
Heights of trees, including those of sapling size to those that were above our heads, were
measured.
Results
As hypothesized, the heights of trees decreased with decreasing age. Site 4, which
was abandoned first, had had the most time to establish plant growth. Sites 3 was then
used and abandoned, then sites 2 and 1 similarly. Site 5 is remnant forest and is used as a
comparison of undisturbed land (Fig. 1). Site 4 had the greatest variance in tree height, as
well as having the tallest trees of the 4 succession plots. Site 3 had relatively few trees,
but all were relatively tall. Site 2 had the same number of trees as site 4, but all trees were
much lesser in height. Site 1 had the fewest amount and shortest trees of the 5 sites (Fig.
2). Since site 1 has had the least amount of time to establish succession plant growth trees
are small and thin. The site is dominated primarily by phragmites.
Discussions
Generally the older the site in terms of the time it’s been abandoned, the greater
the height and vertical distribution of foliage, the greater the tree dbh and growth rate,
and the greater the number of trees and shrubs. However, Team Xtreme’s observed dip in
number of shrubs at site 4 (33) as compared to the next oldest site before it (38), as well
as the flatness of their shrub tally-site number relationship curve in comparison to that for
trees, suggests shrubs’ growth aren’t as at mercy to sites’ states of succession as trees are.
Generally shallow rooting of shrubs enable their growth early in the successional process
(Perry, 1994) and thus shrubs can be a chronological reference point for other vegetation.
Small trees can appear within ten years following disturbances; tall, late-succession trees,
in as little as forty. Shrubs persist all the while unless out-competed for necessary
resources such as sunlight (Packham, 1992). Competition might explain the lack of
shrubs in the un-mined woods adjacent to the quarry sites, since here the thick canopy
favored overstory as well as intermediate- to shade-tolerant understory trees such as
white ash and sugar maple. Team Gray Van’s figures regarding the wooded site’s growth
rates (0.625”/year) and average dbh (12.9”) were higher by far than those for quarry sites’
trees, so maybe the woods’ growing conditions (soil depth, nutrient presence, wind and
sunlight protection) were ideal for the species observed there.
Conclusions
The woods perhaps represent what the quarry sites will look like upon reaching
successional climax, although to verify this continuous measurements of the growth rates
and species composition of the quarry sites’ trees would need to be acquired until the
time when later (e.g. secondary) succesional stages were reached. Our measurements of
tree heights were most varied at the wooded site, with abundant saplings, so reproduction
of species under their own canopies may be occurring there, and thus a steady-state forest
representing stable community composition (climax species) might be represented. But
what did the wooded site succeed? What’s really at issue here is the quarry sites, and all
that’s known about them is that the site abandoned most recently will eventually look like
the site abandoned longest ago in terms of species composition, height, dbh and growth
rate. Primary succession species transform sites by contributing to shade production,
more favorable soil pH (if soil exists) and site nutrients (Packham, 1992). The wooded
site offers a contrast of good growing conditions versus the quarry sites’ bare mineral
soil, although the quarry sites’ primary succession is already ensuring more growth by
more species in future stages.
References
Perry, David. (1994). Forest Ecosystems. The Johns Hopkins University Press.
Baltimore: 130-141.
Packham, J.R., D.J.L. Harding, G.M. Hilton, R.A. Stuttard. (1992). Functional Ecology
of Woodlands and Forests. Chapman & Hall. London.
Pidwirny, Michael. (2004, Nov.). Introduction to the Biosphere. Fundamentals of
Physical Geography [On-line database]. Hostname: PhysicalGeography.net Directory:
http://www.physicalgeography.net/fundamentals/9i.html.
Fig. 1 - Height distribution vs Site
80
70
60
Height (ft)
50
Site 1
Site 2
Site 3
Site 4
Site 5
40
30
20
10
0
0
1
2
3
Site
4
5
6
Fig. 2 - Distribution Among Height Classes vs. Frequency
18
16
Height (ft)
0 to 5
5.1 to 10
10.1 to 15
15.1 to 20
20.1 to 25
25.1 to 30
30.1 and above
14
12
Frequency
Fig. 2
Height Class
1
2
3
4
5
6
7
Site 1
Site 2
Site 3
Site 4
Site 5
10
8
6
4
2
0
1
2
3
4
Height Class (ft)
5
6
7