Growing Threats to Biodiversity ‘arks’
A red-eyed treefrog (Agalychnis callidryas) from Barro Colorado Island in Panama (photo © Christian Ziegler)
Many of the world’s tropical protected areas are struggling to sustain their biodiversity, according to a study just published in Nature by more than 200 scientists from around the world.
Professor William Laurance, from James Cook University in Cairns, Australia, and the Smithsonian Tropical Research Institute in Panama, said that “these reserves are like arks for biodiversity.”
“But some of the arks are in danger of sinking,” he said, “even though they are our best hope to sustain tropical forests and their amazing biodiversity in perpetuity.”
Professor Laurance and his team studied more than 30 different categories of species—from trees and butterflies to primates and large predators—within protected areas across the tropical Americas, Africa and Asia-Pacific.
They estimated how these groups had changed in numbers over the past two to three decades, while identifying environmental changes that might threaten the reserves.
Laurance said their conclusion was that while most reserves were helping to protect their forests, about half were struggling to sustain their original biodiversity.
“The scariest thing about our findings,” said Carolina Useche of the Humboldt Institute in Colombia, “is just how widespread the declines of species are in the suffering reserves.”
“It’s not just a few groups that are hurting, but an alarmingly wide array of species.”
These included big predators and other large-bodied animals, many primates, old-growth trees, and stream-dwelling fish and amphibians, among others.
The researchers found that reserves that were suffering most were those that were poorly protected and suffered encroachment from illegal colonists, hunters and loggers.
Kadiri Serge Bobo of the University of Dschang in Cameroon, Africa, said that it was not just what was happening inside a reserve that was important.
“Almost as important is what’s going on outside it,” he said.
“Eighty-five percent of the reserves we studied lost some nearby forest cover over the past two to three decades,” said Dr Bobo. “But only two percent saw an increase in surrounding forest.”
Deforestation is advancing rapidly in tropical nations and most reserves are losing some or all of their surrounding forest.
The team found many nature reserves acted like mirrors—partially reflecting the threats and changes in their surrounding landscapes.
“For example, if a park has a lot of fires and illegal mining around it, those same threats can also penetrate inside it, to some degree,” Ms Useche said.
The bottom line, the researchers say, is that a better job needs to be done in protecting the protected areas - and that means fighting both their internal and external threats, and building support for protected areas among local communities. Such efforts will help ensure protected areas are more resilient to future threats such as climate change.
“We have no choice,” said Professor Laurance, “tropical forests are the biologically richest real estate on the planet, and a lot of that biodiversity will vanish without good protected areas.”
Among the dozens of scientists involved in the research was the Biodiversity Institute's curator of mammals, Robert Timm.