PARENT SESSION
Poster Session # 17: Aquatic Systems.
Thursday, August 7 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.
Seasonal changes in wetland microflora under varied nutrient and hydrologic regimes.
Mentzer, Jessica *,1, Goodman, Robert 2, 3, Balser, Teri1, 1 Soil Science Department, Madison, WI2 Gaylord Nelson Institute for Environmental Studies, Madison, WI3 Plant Pathology Department, Madison, WI
ABSTRACT- Wetlands are a unique ecosystem type, especially in terms of nutrient cycling under fluctuating hydrology. This makes them important to studies of ecosystem functioning. Many processes of interest in wetlands, such as denitrification and decomposition, are mediated by microbes; therefore, characterization of microflora composition and function may lead to insights about the dynamics of wetland ecosystem functioning and nutrient cycling. In this experiment, we measured several microbial parameters over the growing season in a simulated wetland undergoing varied nutrient and hydrologic regimes. Mesocosms were grown for two years with native Wisconsin wetland species and in the summer of 2002 were subject to three nutrient (none, low and high) and three hydrologic (early season, constant, and intermittent floods) regimes in a full factorial experiment with five replications of each treatment. We collected soil cores at four times: 1) in late May, before treatments started, 2) at two different peaks in the vegetation growth (August and September), and 3) after senescence of the aboveground biomass in early December. We assayed each sample for nitrification potential, denitrification potential, and various enzyme activities (phosphatase, beta-glucosidase, alpha-glucosidase, chitinase, phenol oxidase, cellobiohydrolase, and hemicellulase ). We also performed lipid analysis to determine microbial community structure and composition. Results show that nitrification potentials decreased significantly with increased nutrient levels and that the intermittent flood regime had higher nitrification potentials than early season or constant flood regimes. These results indicate that the nutrient and flood regimes did in fact impact microfloral functions that are important to the wetland system.
Key words: lipid analysis, enzyme activities, wetland microbial ecology, nitrification