Northward march of mangroves impacts fishing, flooding and carbon
ST. AUGUSTINE — Walking along a wooden path winding through Nease Beachfront Park, Danny Lippi pointed to coastal trees sprouting from the shrubbery around him. The exotic species were brought here by warming temperatures — bringing business opportunities for the local arborist.
“All of these are mangroves,” Lippi said, surrounded by the young perennial plants, blooming with hues of green and golden yellows. “You can actually see that line where the upland vegetation just stops.”
Demand for Lippi’s mangrove trimming service has been growing as the trees have been accumulating northward, starting to block coastal views from Ormond Beach to Palm Coast. Their northernmost limit in the U.S. sits about 70 miles from St. Augustine on Amelia Island, and it continues to shift.
Ranges of mangroves have naturally waxed and waned over the years, influenced by the weather, but with climate change has come a crucial reduction in crop- and tree-killing freeze events.
The last freeze strong enough to wipe out mangroves took place in 1989. This decline in the number of frosts, coupled with intensifying storms spreading seed-like propagules, is causing the trees to push poleward.
Smithsonian Environmental Research Center research shows mangrove coverage has doubled along Northeast Florida’s coast since 1984. This freshly arrived abundance of mangroves may block waterfront views and squeeze out marsh wildlife, but the tropical trees’ value is celebrated by the state.
Florida legislators regard the trees as storm buffers and coastal habitat, and the Mangrove Preservation and Trimming Act safeguards mangroves and forbids their trimming by anyone lacking arborist certification. More than 500 violations have been issued since the legislation passed in 1995, with some businesses and residents hit with fines of tens of thousands of dollars each. On average, researchers have estimated mangroves protect $13 billion worth of property in the U.S. annually from storm and flood damage.
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