Effects of Typha x glauca on methane emissions in freshwater ecosystems: implications of invasive species effects on global climate change.

Abstract

Across the globe, freshwater ecosystems play vital roles in global nutrient and emission cycles and provide key ecosystem services. Great Lakes wetlands have increasingly been dominated by an invasive cattail hybrid? Typha x glauca. Cheboygan Marsh, a Great Lake marsh formed by Lucustrine deposits, was invaded by Typha in the 1950’s. Resent surveys indicate Typha now dominates two-thirds of the ~150 ha marsh. Typha has the propensity to alter freshwater ecosystems by forming dense stands of live and dead biomass. As Typha biomass accumulates and decomposes in the soil it can act as a fuel for methanogenesis when coupled with anaerobic conditions often found in these ecosystems. As tipping points in global climate change are quickly being approached research on both anthropogenic and natural emissions are warranted. In this study we used both a field and mesocosm experiment to test for the effect Typha invasion is having through its leaf litter on methane emissions. We found soil organic carbon to be in much higher concentrations in Typha zones than Native vegetation zones dominated by sedges and rushes in Cheboygan Marsh. In the mescocom array we also found a positive correlation between higher soil organic carbon and increased methane flux rates. These finding may suggest that the possibility exists for Typha invasion to play a significant role in future climate change.