Name
Foundations of Biology
Lab Summary
Population Ecology: Sand & Dune Succession
Plant Density in the Dunes
250
8
7
6
5
150
4
100
3
2
Woody Plant Density
Marram Grass Density
200
Marram Grass Density
(marram grass/sq. m)
Woody Plant Density
(woody plants/sq. m)
50
1
0
5-
0-
5
m
et
er
s
10
m
et
10
er
-1
s
5
m
et
15
er
s
-2
0
m
et
20
er
s
-2
5
m
et
25
er
s
-3
0
m
et
30
er
s
-3
5
m
et
35
er
s
-4
0
m
et
40
er
s
-4
5
m
et
45
er
s
-5
0
m
et
er
s
0
Distance from the edge of the dune
Based on the results plotted on the graph, the distribution of plants showed a
density change going from the middle beach to a 60-meter distance beyond that. The
woody plants showed an upward curve, increasing in density as the distance increased
from the middle beach, where the measurement was begun. In addition, it was also
observed that the circumference of these plants increased with increasing distance. The
plants exhibited changes ranging from having only thin and flexible branches to having
well developed and sturdy trunks. These results complied with what should be expected
from a typical dune succession. Since the middle beach is generally a harsh environment,
being constantly subjected to blowing sand and temperature fluctuations, there are
usually not enough nutrients in the sand to support dense vegetation. The middle beach,
however, has enough stability to support plant life at this level; and as indicated by the
marked increase in density of the woody plants, this stability increases going past and
farther up this level.
The marram grass, on the other hand, indicated a sudden surge between the
distance of 0-10 meters, a decline in density between 10-30 meters, another increase on
the 30-35 meters mark, and finally, a downward trend from the 35-50 meters distance.
This didn’t quite meet the trend that should be expected from a sand dune succession;
however, it still showed the general trend leaning towards building a sand dune. In
regards to the difference between the expected marram grass density and the gathered
data, the variation, quite possibly, was caused by several factors that disturbed the
landscape in this particular area. One, the nutrients were not evenly distributed in this
patch of land; and two, the marram grass dried up because the woody plants, being more
deeply rooted into the ground, absorbed more of the little nutrients available for both
plants. The second reason is more logical because, as shown by the graph above, the
density of the marram grass decreased as the density of the woody plants increased,
indicating perhaps that the two were engaged in some sort of “food” competition.
Nonetheless, as one moved upwards toward the foredune area, and more nutrients
became available for the two to share, the densities of both marram grass and woody
plants increased at rate relative to the other giving rise to the Sand Dunes.
THE END!
EL FIN!