John Smit29 September 2014
Abstract
For this lab, my group and I collected data from the Benedict Forest Preserve. The lab required our group to measure the trophic composition and productivity of the preserve. We did this by measuring the number of autotrophs, herbivores/detritivores, and consumers in the area we were instructed to stay in, and by measuring the biomass, energy, and ecological effiencey of autotrophs, herbivores/detritivores, and consumers in the given area.
Introduction
The Benedict Forest Preserve was studied to demonstrate the structure of an ecosystem, and since forests are highly productive ecosystems it was necessary to gather information on both living and non-living organisms. The main data we were looking for in this forest lab were: (1) the number of autotrophs, herbivores/detritvores, and carnivores; (2) the biomass (g/m^2) for the autotrophs, herbivores/detritivores, and carnivores; (3) the energy (kcal/m^2) for the autotrophs, herbivores/detritivores, and carnivores; (4) the efficiency of the energy transfer from one trophic level to the next; (5) and decomposition for leaf litter bags.
We have to assume that the majority of biomass in terrestrial communities is produced by autotrophs.
The objective of this lab was to investigate several emergent properties of an ecosystem, primarily the trophic composition and productivity of a forest ecosystem. Relative to the 0.01% of the forest, trees account for around 99% of the biomass and energy in the forest ecosystem. Our group’s hypothesis expected the moisture rates of two different leaf species to be different.
Methods
The site of the Benedict Forest Preserve was like any ordinary forest preserve: trees everywhere, the ground was littered with leaves & insects, and since it was the beginning of fall/end of summer, it was still a lively ecosystem. We got to the location around 2: 30 and the temperature was in the high 70’s-low 80’s with the sun out with very little clouds. However once we got to our area of data collection, the trees acted as a blockade to the sun.
The first step in the lab was to record the total number of trees in a 25m X 25m plot. From there, we randomly chose a 10m X 10m plot in order to measure and record all trees with a DBH greater than 3cm. In order to successfully count the number of herbaceous plants, our group remained in the 10m X 10m plot, however the plants needed to be counted in two random 1m^(2) plots. Finally, our group classified and counted the wide array of carnivores, detritivores, and herbivores in a 0.1m^ (2) plot, while still being limited, space-wise, by the 1m^ (2) plot. We also had to make a second 0.1m ^ (2) plot in order to collect all leaf litter within the instructed space (1m^ (2)). For estimating litter decomposition, leaves were collected and placed in two types of bags, one that excluded detritivores and one that didn’t. Since the TA’s collected the bags, and placed them in an oven at 105 degrees Celsius for 24 hours, then weighed, we had to use these bags to estimate litter decomposition in the presence of