Wetland Forest Regeneration Dynamics and Productivity in Southeastern Cypress Swamp Ecosystems

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Relict forests (i.e., forests unable to reestablish after disturbance) may develop in the southeastern U.S. in future predicted extreme climates of temperature, flooding, and drought, according to the International Panel on Climate Change.

North American Bald Cypress Swamp Network

North American Bald Cypress Swamp Network

The Science Issue and Relevance: Relict forests (i.e., forests unable to reestablish after disturbance) may develop in the southeastern U.S. in future predicted extreme climates of temperature, flooding, and drought, according to the International Panel on Climate Change. Juvenile stages of forest species have a more limited tolerance for climate extremes than adults, therefore lack of regeneration can be used to detect the formation of relict forests. This study assesses the regeneration status of relict cypress forests in the southeastern U.S.

Methodology for Addressing the Issue: These studies are conducted in the North American Bald Cypress Swamp Network (NABSCN), which is a long-term study network of 70 wetlands located throughout the southeastern United States along the Mississippi River Alluvial Valley from southern Louisiana to southern Illinois, and the Gulf and Atlantic coasts from Texas to Florida and Maryland/Delaware, respectively. The network has replication at the landscape level, with five replicate swamps per geographical area. Within each wetland, production, growth, and regeneration are studied. Annual estimates include above- and below-ground production, tree growth, seed production, seedling and sapling density, and seed bank structure. Environmental measurements include water, sediment, and salinity dynamics; many sites have water level recorders and Sediment Elevation Tables, which are used to measure the relative change of wetland sediment elevation.

Future Steps: Swamp trees show signs of stress in some locations, particularly in the southwestern part of the region in areas with high levels of water extraction and/or recurring severe drought. This assessment is based on their production and regeneration status. Coastal swamps are vulnerable to high salinity, so that fresh water management may be helpful.

The project will construct models of climate change responses in freshwater swamps. Managers use the information to design water management strategies to minimize the loss of biodiversity and maximize the health of coastal and inland forests. Results of this study are used as a part of ongoing water management plans in southern Illinois and eastern Texas.

Related projects: Modeling the connections between hydrology, water quality, and ecosystem health to support coastal preservation efforts across the Northern Gulf Coast; Damage, resilience and change thresholds of forest (maritime, cypress) and barrier island vegetation of the Delmarva Peninsula following Hurricane Sandy; Collaborative geographic studies on methane emission, and genetic variation.