Collaborative Research: Hydrologic Connectivity and Water Storage as Drivers of Carbon Export and Emissions from Wetland-Dominated Catchments

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Worldwide, rich forested wetlands have been converted to agriculture through ditching and draining. These wetlands are important for regional water and carbon cycles. They reduce downstream flooding through water storage, providing dissolved organic carbon to downstream ecosystems, and contributing to carbon storage. While efforts are being made to restore drained wetlands, recovery of ecosystem services has lagged. Research is urgently needed to understand how hydrology influences delivery of wetland ecosystem services to guide future restoration and management. This project will investigate water movement and carbon cycling in wetland-rich Delmarva Bay. Research will focus on freshwater wetlands that are often isolated from adjacent rivers. These small wetlands are vulnerable to land-use change, and their impact on regional water and carbon cycling is poorly understood. This research will inform management, contribute to meeting national research priorities, and build capacity in the scientific workforce. Students will be engaged in all aspects of the research, as well as in interactive meetings with managers and training workshops on actionable science. This project will also provide data on carbon budgets and in advancing next-generation models to estimate carbon dynamics. This research will test the hypothesis that water storage capacity (WSC), or the amount of water a single wetland or group of wetlands can store, is a principal driver of wetland- and catchment-scale hydrology, carbon emissions, and downstream carbon export. Using coupled empirical and modeling components, this project will quantify: (1) WSC at wetland and catchment scales and resulting variation in water levels, residence time, and water export; and (2) consequent influences to carbon dynamics at both wetland (DOC concentration and composition, CH4 and CO2 emissions) and catchment scales (DOC export and composition, CH4 and CO2 export). Linked hydrologic and biogeochemical data will be collected in 18 wetlands across six study catchments that vary in WSC, with more intensive data collection (e.g., in situ, high temporal resolution) within one wetland per catchment. At the catchment scale, each catchment outlet will be monitored for time series of water discharge and carbon composition and export. Derived empirical relationships and calibrated process-based hydrologic models will advance predictive understanding of wetland carbon emissions and the shunting of DOC, CO2, and CH4 from upstream wetlands to catchment outlets. Expected outcomes linking WSC and associated hydrologic controls on carbon biogeochemistry are required to inform restoration practice and global carbon models.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.