Invertebrate and leaf litter dynamics in the DePauw Nature Park
Karl Koehler and Vanessa Fox
Biology Department and Science Research Fellows Program, DePauw University
Using the DePauw University Nature Park and Arboretum, we set up a study on invertebrate abundance and biomass and leaf litter cover, depth, biomass and decomposition. Leaf litter decomposition is an essential element of the nutrient cycle of an ecosystem. We hoped to gain a better understanding of the role of invertebrates in the decomposition process. We hypothesized that there would be a correlation between decomposer invertebrates (i.e. beetles, centipedes, springtails, etc.) and areas of high litter decomposition. We established upland and lowland transects at three sites (QS, QH, and ARB). Each transect contained 10 evenly spaced testing zones. We measured leaf litter decomposition using wire mesh bags and collected invertebrates in pitfall traps at each testing zone. Isopods and crickets were abundant at all three sites. Beetles were more abundant in the upland than lowland transects. Centipedes were more common at QH and QS than the ARB. Crickets were more numerous at the ARB than the other sites. Approximately 3 to 7 percent of the leaf litter in the mesh bags decomposed during the six week period, but there were no differences in decomposition rates between the three sites. Leaf litter depth, cover, and biomass were lower at QS than the ARB or QH. The lower leaf accumulation at QS may be attributed to forest composition. Elm trees, a species with rapidly decomposing leaves, were more abundant at QS than the other sites. From our data it is unclear whether or not the high abundance of one or more species of invertebrates has a direct effect on litter decomposition. Over time continued monitoring of the litter bags should yield a discernable amount of decomposition. This will allow us to compare upland to lowland and get a better idea of the decomposition rates at each site over time.