CORAL GABLES, FL. -- The key to understanding how future hurricanes and sea level rise may trigger changes to South Florida's native coastal forests lurks below the surface, according to a new model linking coastal forests to groundwater. Just inland from the familiar mangroves that line the coasts lie hardwood hammocks that are sensitive to salinity changes in water found in the soils.
University of Miami (UM) Ecologist Donald L. DeAngelis, who is also a researcher for the U.S Geological Survey (USGS), has worked with collaborators to develop a novel computer model describing the underlying forces that maintain this vegetative boundary. The findings, published in the current issue of the journal Landscape Ecology, indicate that large pulses of saline water into the hammock vegetation may cause mangroves to invade areas now populated by hardwood hammocks.
"A high level of salt in the soil favors the mangroves and stresses the hardwoods," says DeAngelis, professor in the Biology Department at the UM college of Arts and Sciences and one of the principal investigators of this project "Hardwood hammocks are a unique feature of the Everglades, they are home to many species, and if they decrease in numbers that will mean a loss of habitat for some organisms."
During storm surges, the salty winds and waves rush into areas of brackish water. The likelihood of such salt water overwash from the coast is expected to increase as sea level rise affects the natural coastal processes in the region.
The study is one of the first to couple vegetation dynamics with hydrology and salinity of the area in order to study the factors affecting the forest boundary. The work reveals that the sharp mangrove-hammock boundary, or ecotone, is defined by a combination of factors such as water levels during the dry season, tides, changes in the land's features, and trees own ability to alter the environment to their benefit (a process known as positive feedback).
|Contact: Marie Guma-Diaz|
University of Miami