The Southeast hosts an impressive network of forested wetlands. These wetlands improve water quality, reduce flooding, store excess carbon and provide important habitat for wildlife. They are also particularly vulnerable to changes in climate and land use.

USDA Forest Service scientist Peter Caldwell and researchers from North Carolina State University have designed a model to assess the impacts of climate change on wetland boundaries along the east coast.

The researchers derived future daily temperature and precipitation values from the Hadley climate forecast model. These data were analyzed in another model called DRAINMOD along with soil and hydrology records to predict levels of current and future water tables.

The team analyzed site data from an isolated depressional wetland in Pitt County, North Carolina. Analyses were repeated for sites in Portland, Maine; Easton, Maryland; and Miami, Florida. The modeling results were published in the journal Wetlands.

The team applied this definition of a wetland-hydrology boundary: When the water table is within 30 centimeters of the soil surface for two weeks or more during the growing season, land below this point of the boundary is considered a wetland, while land upslope is not.

Reduced wetland acreage could significantly impact biological process. Increases in temperature may lead to increased methane and carbon emissions, as well as heightened drought and wildfire risk.

In addition to increased temperatures and evapotranspiration, wetlands are influenced by changes in vegetation, inter-wetland relationships and surrounding land use. Regional differences in these factors will influence changes to the water table.

“Essentially, this work showed that there will be less wetland acreage in the future as a result of climate change,” said Caldwell.