SEE-U 2000: Black Rock Forest - Module 5:Exercise 5

General Methadology for Instructors and TAs
## Exercise 5: Deer Herbivory And Plant Diversity Module 5: Community Ecology: An Introduction to the Players and How to Measure Communities Printer format Instructor gives the biological background during the lecture on role of herbivores in the ecosystem, emphasizing the diversity of types of herbivory Introduction to community ecology and role of herbivory in structuring plant and animal communities. Brief mention of coevolution and the chemical arms race between insect herbivores and their host plants Background literature and description of current deer explosion in Northeast will be provided Discussions of reasons for the absence of local constraining factors that would otherwise control the deer population (predation, parasites, competitors, etc.) Introduce edge effects and how deer herbivory may mimic these effects on a larger scale and deeper into the forest Students will be given background information on the history of the deer exclosures. Two adjacent plots clear-cut 12 years ago. One was fenced immediately after clear-cut, one was not Students will be asked at the end of the lecture to begin thinking of how to experimentally answer the question: "What is the effect of deer herbivory on plant diversity and abundance?" Independent variable in the experiment is deer herbivory presence or absence Most other abiotic forces will be factored out because the experimental plots are immediately adjacent Abiotic differences should therefore be negligible Students need to sample randomly about the plot to minimize sampling biases Students will need to measure dependent variables that best summarize the successional status of the plot and the effects of deer herbivory Dependent variables of the plants in their plots that they could use in their experimental design, not all of which are of equal utility in answering the question — several do not summarize the status of the plants within the experimental plots but are still describe aspects of the plots Leaf litter diversity Leaf litter depth Leaf litter volume Plant diversity of woody plants Plant diversity of annuals Plant abundance Diameter at Breast Height (DBH) Average plant height Others? After lecture, before the start of field time, the students will be asked to confer with their labmates and will be required to draw up a plan outlining the experimental design of their group The best design will be determined by consensus and will be used for the entire class This will allow for pooling of the data and enhanced statistical power Students should also determine the necessary list of materials and provide the list to the instructor — the instructor will determine whether there are sufficient materials to address the experimental design Possible methodology Within each of the two plots, students lay out a baseline Randomize the sampling distances and directions from the baseline Place one meter square quadrats on ground Collect samples of all plants growing within the quadrat Measure leaf litter depth Measure the Diameter at Breast Height (DBH) of all woody plants growing within the quadrat Harvest and weigh the leaf litter within the quadrat Identify the leaves within the leaf litter to species and create diversity counts Enter raw data into a clickable aerial photo of both sites for distance learning and for a more complete set of data to be collected (see below for a description of the clickable photos) Do statistical analyses (chi-square on species diversities; t-test on DBH, litter depth, and litter weight) Plot out data on Excel using graphing function Present the work as an oral report at the end of the day, referring to the illustrations and statistical tests they performed