Carbon Sequestration

Mangrove forests have migrated inland over the past few decades at many locations along the northern Gulf of Mexico coast. This expansion has been attributed to factors associated with climate change, such as increased salinity resulting from sea-level rise and longer intervals between winter freezes, which can kill cold-intolerant mangrove species.

Wetland restoration and creation efforts are increasingly proposed as means to compensate for wetland losses. To address the need for evaluating the development of ecosystem structure and function in restored and created wetlands, USGS compared created tidal wetlands sites to natural mangrove wetlands in Tampa Bay, Florida.

Wetlands have the potential to absorb large amounts of carbon dioxide via photosynthesis, and flooded soils have low oxygen levels which decrease rates of decomposition to promote the retention of soil carbon. However, the type of greenhouse gases emitted from wetlands varies by wetland type and soil condition. A suite of approaches are being used to assess fluxes of greenhouses gases, like...

Tidal freshwater forested wetlands - TFFWs - can be found in the upper intertidal areas of many estuaries and act as a transition between coastal marshes and bottomland hardwood wetlands. However, it is because of their location that makes them vulnerable to sea-level rise, and they are constantly transitioning to different wetland types. USGS addresses how various processes are affected in TFFWs...

Sudden Marsh Dieback - SMD - has been documented for the past two decades throughout coastal areas of the United States. With these large-scale diebacks comes the loss of ecosystem functions and services. USGS scientsts use field work and greenhouse studies to investigate the factors that control the resilience and resistance of coastal salt marshes to SMD.

USGS research in the Florida Everglades will provide information on how environmental conditions and disturbances impact carbon storage in mangrove systems.

Coastal wetlands provide valuable ecosystem services such as wave attenuation, surge reduction, carbon sequestration, wastewater treatment, and critical habitats for endangered fish and wildlife species. However, wetland loss threatens the capacity of coastal wetlands to provide these ecosystem services.

This study will employ a space for time substitution to show long-term effects of rising sea-level and increasing salinity on vegetation community structure, primary production and decomposition. Productivity and decomposition rates will be estimated for four wetland plant community types defined by salinity zones and dominant plant species.

Wetlands along the Gulf of Mexico coast play an important role in the global carbon cycle, but as they rapidly convert to open water, their potential for carbon storage is declining. USGS is working to provide accurate, long-term marsh soil carbon sequestration rates.