Carbon sequestration and net greenhouse gas emissions are important ecosystem services that define the climate-mitigating potential of a system. Emerging research shows that coastal marshes can be net sources or sinks of greenhouse gases depending on local vegetation, flooding regimes, water salinity, and disturbance history. Over the past few centuries, restriction to tidal flow has been a common management practice that can alter plant habitat and shift microbial and chemical processes that drive a systems potential to uptake and emit greenhouse gases. However, it is currently unclear how tidal restriction can interact with known drivers of greenhouse gas emissions in coastal marshes to determine landscape level patterns.
The overall objective of this study is to improve understanding of the sources and sinks of greenhouse gases in tidal versus impounded coastal marshes to inform management decisions regarding marsh resilience and climate mitigation. We will augment ongoing landscape-scale work with targeted studies at the plant scale to develop new mechanistic knowledge. Our specific objectives are: 1) to identify the mechanisms underlying regulation of carbon dioxide (CO2) and methane (CH4) production and consumption by local vegetation that can vary between tidal salt marshes and impounded wetlands and 2) to understand how these change at diurnal and annual timescales.