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Decades of Fertilization Increase Greenhouse Gas Emissions at Great Sippewissett Marsh, Cape Cod, USA
Citation:
Martin, R., C. Wigand, E. Elmstrom, AND I. Valiela. Decades of Fertilization Increase Greenhouse Gas Emissions at Great Sippewissett Marsh, Cape Cod, USA. Coastal & Estuarine Research Federation (CERF) 24th Biennial Conference, Providence, Rhode Island, November 06 - 09, 2017.
Impact/Purpose:
Human impacts such as hydrological alteration and eutrophication can alter biogeochemical cycling in coastal wetlands, including fluxes of the gases carbon dioxide, methane, and nitrous oxide. In these experiments, we test effects of increasingly freshwater conditions and of eutrophication on fluxes of carbon dioxide, methane and nitrous oxide. Results demonstrate that decreasing inputs of seawater increase methane emissions and eutrophication increases nitrous oxide emissions in coastal wetlands. These findings have implications for resource management scenarios in which wetland ecosystem services of carbon and nitrogen sequestration are prioritized.
Description:
Coastal wetlands’ ecological and biogeochemical characteristics make them important sites of carbon sequestration and nitrogen interception and transformation. In coastal wetlands, decomposition rates are low and productivity is high, making these systems net sinks of carbon dioxide (CO2). However, anthropogenic changes such as tidal restriction and nutrient pollution may cause wetland soils to act as sources of methane (CH4) and nitrous oxide (N2O). In this talk, results of experiments testing responses of coastal wetland CO2, CH4, and N2O fluxes to nutrient pollution and hydrological changes are presented. To test effects of chronic eutrophication, we measured CO2, CH4 and N2O fluxes from experimental plots at Great Sippewissett Marsh receiving high doses of fertilization (1,572 kg N ha−1 year−1) and in control plots (12 kg N ha−1 year−1). To test responses of coastal wetland greenhouse gas fluxes to changes in tidal hydrology, we measured CO2 and CH4 fluxes in a reciprocal transplant experiment in which soil blocks from the freshwater-influenced upland/marsh border and the regularly-flooded high marsh Spartina patens zone were exchanged. Results of these experiments demonstrate increased emission of N2O and CH4 by chronic fertilization and tidal restriction scenarios, respectively.