Prairie potholes wetland are noted for their cyclic changes in their vegetation density and distribution in response to 5-30 year wet-dry cycles. In Goose Lake Marsh in central Iowa, soil exposure, emergent and floating-leafed plant distribution, and dissolved oxygen concentrations at 10 cm below the water surface were recorded during July from 1995-2006. Methane concentrations were highest directly above the soil in the emergent vegetation area; these results are likely due to the buildup of sufficient litter biomass which stagnates the water, interferes with gas transfer across the air/water interface, and shades the water column. The results suggest that longer-term patterns of vegetation and soil exposure have indirect as well as direct effects on biogeochemical cycles.