Wetland ecosystems play a significant role in the global carbon cycle, and yet are increasingly threatened by human development, climate change, and shifts in populations of large grazers. The loss of intact wetland systems heightens the need for effective wetland creation and restoration. However, wetland ecosystems are highly complex, complicating efforts to replace the functionality and delivery of ecosystem services associated with natural wetlands. Increasing waterfowl populations pose a threat to the development and persistence of created wetlands, largely through intensive grazing that can shift vegetation community structure or altogether limit desired plant establishment. This study capitalizes on a long-term herbivore exclusion experiment to evaluate how herbivore management impacts carbon storage in two created wetlands in Western New York State, USA. Changes in plant communities, above- and belowground biomass, soil carbon, and decomposition rates were evaluated in plots with and without the influence of grazers. Grazing reduced vegetation cover by approximately 34% in the height of the growing season, and led to similar reductions in aboveground biomass in a permanently flooded wetland, but had minor impacts in a seasonally flooded wetland. In the permanently flooded wetland, where we also measured fluxes of carbon dioxide and methane, this shift in vegetation resulted in reduced carbon uptake through primary productivity and a 27% reduction in soil carbon. During the summer, carbon fixation in grazer exclusion plots was 49% higher than in control plots, but methane emissions was also 62% higher. Our results suggest that grazers play an important role in vegetation dynamics in created wetlands and as a result shift carbon storage and greenhouse gas production.
Environmental Science (MS)
Department, Program, or Center
Thomas H. Gosnell School of Life Sciences (COS)
Anna Christina Tyler
Spangler, Delanie, "Effects of grazer exclusion on carbon cycling in created freshwater wetlands" (2019). Thesis. Rochester Institute of Technology. Accessed from
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