Tuesday, August 3, 2010
Exhibit Hall A, David L Lawrence Convention Center
Kirsten V. Otis, Sigrun Kullik, Jonathan M. Schmidt, Shelley L. Hunt, Andrew M. Gordon and Paul K. Sibley, School of Environmental Sciences, University of Guelph, Guelph, ON, Canada
Background/Question/Methods Vernal pools are small, seasonally flooded wetlands found throughout the forests of North Eastern North America which fill with precipitation during the wet fall and spring seasons, however dry-down each summer to become indistinguishable from non-flooded uplands. Leaf litter decomposition rates have been observed to increase when exposed to temporary flooding in ephemeral environments such as vernal pools, however studies with greater replication and sampling frequency, to capture the natural variation inherent in this system and to allow for prediction of decomposition rates under changing precipitation patterns. The objective of this study was to compare leaf litter decomposition rates within vernal pools to those from adjacent non-flooding upland with greater replication and sampling frequency than previous studies. Using the litterbag method, wetland and upland decomposition rates of air-dry Red Maple (Acer rubrum L.) leaves were compared at 25 individual vernal pools within a mixedwood upland forest near Dorset, Ontario. Litterbags were deployed in October 2008 and sampled five times between October 2008 and October 2009, with the oven-dried mass of each litterbag measured upon removal. The mean percent mass remaining were compared by pool and wetland/upland via an ANOVA using SAS 9.2.Results/Conclusions
In this experiment, 1000 litterbags were collected over the course of the year, and after accounting for sub-sampling a total of 250 mass loss samples were obtained, partitioned between wetland and upland for 25 individual pools. The overall percent mass remaining after one year in the wetland was slightly but significantly lower than the upland, 67.6% and 70.4% respectively (se=0.27, ANOVA orthogonal contrast, p<0.0001, α=0.05). This research confirms previous studies, with added robustness of increased replication and sampling frequency. It will add significantly to the fields of wetland and forest ecology by increasing our understanding of how abiotic hydrological conditions such as temporary flooding can influence ecosystem processes over space and time. Knowledge of these linkages can be applied in understanding how anthropogenically-induced changes, such as land-use and climate change, may influence larger-scale processes. This study will also be novel in the vernal pool literature in its time frequency and degree of replication.
