Conservationists have long known that clearing forests will cause animals to die off. But what happens when you carve up forests into a bunch of tiny islands?
A new study published in Science answers just that question, showing how forest fragmentation can lead to almost complete mammal extinction in a given area much sooner than previously thought.
The findings represent more than two decades of research for UC San Diego biologist David Woodruff. He's been traveling to Thailand's Chiew Larn reservoir off and on since the early 1990s.
Today, the man-made lake is a tourist destination. But a few decades ago, it didn't even exist. Once a lush forest, it was broken up into a handful of islands when the government built a hydroelectric dam along the Khlong Saeng river.
Working with an international team of researchers, Woodruff studied how small mammals have fared on the few patches of preserved forest remaining above water.
He knew these native species would eventually die out on the isolated islands. "A fragment, once it's isolated, has in it a time bomb," he explained. But Woodruff and his colleagues were surprised to see just how quickly extinction came to pass.
The researchers thought species would disappear within 100 years. But upon returning to Chiew Larn in 2012, they found that most small mammals had been wiped out in merely 25 years.
One change Woodruff noticed over the years is the way the islands sound.
"Unfortunately, the forest is going silent," he said. "The birds are going, the mammals are going. It's not the place it was, and that's happened very quickly."
Woodruff said conservation efforts need to focus on keeping larger fragments of forest intact and interconnected. "A mass extinction is not inevitable," he stressed. "We know what to do, but we're not geared up to doing it at the speed with which we should be responding to the destruction of the planet."
