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Sept. 27 (UPI) -- Efforts to restore and reconnect isolated patches of pine savanna in South Carolina is paying off. The nearly-two-decade project has yielded an increase in the number of plant species within each fragments, as well as curbed the loss of animal species.
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For thousands of years, the longleaf pine was the most abundant tree species in the United States. It thrived in the savannas that stretched across the American South, from the Carolinas to Florida and across to Texas. Until the arrival of European settlers, longleaf pine savannas covered more than 90 million acres.
Hundreds of plant and animal species call pine savannas home, including unique grasses, the gopher tortoise and the endangered red-cockaded woodpecker. But each year, there is less habitat than there was before. Most of the patches of pine savanna that remain, after centuries of human development, are too small and isolated to sustain diverse communities of plants and animals. It's the story of important ecosystems all over the world.
"We know that habitat fragmentation and loss is the number one driver of species extinctions in the U.S. and across the globe," lead study author Ellen Damschen, professor of integrative biology at the University of Wisconsin-Madison, said in a news release. "We need conservation solutions that can protect existing species and restore lost habitat."
For the last 20 years, scientists have closely monitored biodiversity among plots of pine savanna in South Carolina. At the outset of the project, conservation researchers worked to link the fragments, each the size of two football fields, with 500-by-80 feet corridors of restored habitat.
Each year, the connected fragments experienced a five percent increase in the number of new species arriving and a two percent decline in extinction rates. Scientists described the biodiversity benefits of their efforts this week in the journal Science.
"Like compound interest in a bank, the number of species increases at a constant rate each year, resulting in a much larger bottom line over time in habitats that are connected by a corridor than those that are not," Damschen said.
Previous studies looking at the relationship between habitat and biodiversity have focused on total size.
"From a biodiversity standpoint, we know habitat area is important," said Damschen. "But we also need to be thinking about the network of remaining habitat and how to reconnect small parcels."
In California, where roads and neighborhoods have carved up forests in the hills of Santa Monica, mountain lions have found themselves isolated from potential mates and the new genetic material needed to maintain the population's health. Conservationists have been working to develop green bridges and other kinds of corridors to connect fragments of habitat.
"It's not always possible to make more habitat, so connecting existing habitat is another tool in the conservation toolbox," said co-author John Orrock, also a professor of integrative biology at UW-Madison.
Inspired by the South Carolina project's success, researchers and conservationists with the Nature Conservancy and the Virginia Department of Conservation and Recreation Division of Natural Heritage have started working to restore longleaf pine savannas along the northern edge of the tree's historic range.
"It's a race against time when it comes to restoring plant biodiversity, especially in the face of accelerating climate change and landscape fragmentation," said Brian van Eerden, director of the Nature Conservancy's Virginia Pinelands Program. "We need the best available science from long-term, large-scale studies like this to inform how to connect and manage our conserved lands to ensure the native species have the best chances to survive and thrive."
