A decline in the frequency of extreme cold weather in Florida has allowed coastal mangrove forests to expand northward, finds a study published this week in Proceedings of the National Academy of Sciences.
The research, based on analysis of satellite and temperate data, found that mangroves in the Miami area and northward have expanded by 1,240 hectares since 1984.
“Between Cape Canaveral National Seashore and Saint Augustine, mangroves doubled in area,” noted a statement issued by the University of Maryland.
The researchers, led by Kyle C. Cavanaugh of the Smithsonian Institution and Brown University, attribute the change to a drop in the number of days when temperatures fell below 28.4 degrees Fahrenheit (-4 degrees Celsius), a level where frost can kill mangrove trees.
The findings suggest that climate change could drive mangrove expansion poleward.
“Mangroves cannot tolerate extreme freezing temperatures and so are generally limited to tropical environments,” the researchers write. “However, climate change in the form of increasing temperatures has the potential to facilitate increases in mangrove abundance near tropical–temperate transition zones.”
While expansion of mangrove forests could encroach into other ecosystems, there may be some beneficial tradeoffs. Other research has shown mangroves to provide a number of important ecosystem services, including carbon storage, buffering coastal areas against storm damage and erosion, and supporting fisheries.
CITATION: Cavanaugh et al. Poleward expansion of mangroves is a threshold response to decreased frequency of extreme cold events,” published online Dec. 30, 2013 in Proceedings of the National Academy of Sciences.