Elevation Zero
4:00 pm
Fri November 15, 2013

Sea-Level Rise Taking The Pines Out Of Big Pine Key

Credit Nancy Klingener / WLRN
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Big Pine Key takes its name from the pine forests that cover the island, about 30 miles from Key West. Rare plants and endangered animals — such as the Key deer — live in those forests.

But now the forests and hammocks are threatened by the rising seas around and beneath them.

Robert Ehrig points to a piece of land that was hardwood hammock when he came to live here 35 years ago.

“All the palms in here are dead,” Ehrig said. “The last one died about the time of Hurricane Wilma, about seven, eight years ago, maybe right after. Those palm trees were eight, 10-feet tall, which means they were 70 to 100 years old because they’re a very slow growing species and they died simply because of the prolonged tides.”

Big Pine Key has pine forests and hardwood hammocks because it sits on a freshwater lens. They need that freshwater to survive. The island is made of limestone, which holds rainwater -- almost like a sponge.

But that sponge is porous to all kinds of water.

Chris Bergh is South Florida conservation director for the Nature Conservancy. And he lives on Big Pine.

“As the sea rises, the freshwater is pushed out by saltwater. As the sea rises, the island itself becomes smaller. And as the sea rises, the freshwater dependent species start to give way,” Bergh said. “They start to lose the battle between themselves and saltwater tolerant species like mangroves.”

Bergh says sea-level rise affects islands like Big Pine differently from mainland South Florida.

“Not only as the sea rises does it come in from every direction, from north, south, east and west, but it also comes up from beneath,” he said. “It comes up through the ground itself and the saltwater actually moves up through the rock, bubbling up, so to speak, from below.”

And that’s why the pines of Big Pine Key are disappearing.

Despite the changes he sees on his land, Robert Ehrig says in some ways, it’s still the quiet, rural island he discovered back in the seventies.

“I remember coming to Florida after being in Hawaii and the Virgin Islands, Puerto Rico and Central America and being kind of disappointed until I got to the Keys,” he said. “Because then I was out of the country again.”

Back then, high tides would cover his property maybe five times a year. Now he says it’s more like thirty. His land is now dotted with the skeletons of trees like slash pine, poisonwood and varnishwood. In their place, red mangroves are thriving, because they do really well in saltwater.

“What’s happening here is the natural history is really changing,” Ehrig said. “And it’s changing rapidly for a number of reasons, but the most pronounced reason is sea-level rise.”

Big Pine, like all the Florida Keys, was created by the sea. It’s the sea that draws the people who choose to make their lives here — and the sea that shaped the land. The sea is still altering the landscape, changing the ecosystem before our eyes. We notice when a storm surge covers the island – but you have to live here for awhile to see the rhythmic repeated tides that are washing ever higher over the land and the retreat of the pine forests, leaving a monoculture of mangroves in their wake.