26 July 2012
Biodiversity is declining at an alarming rate in around half of the world’s protected tropical forest reserves, according to the most comprehensive study ever conducted.
Published today in Nature, the survey by more than 200 scientists world-wide, including Monash University’s Dr Patrick Baker, assessed the health of 60 tropical reserves over a 20 to 30–year period and found that stressors such as habitat disruption, hunting and forest-product exploitation had taken a toll.
Lead author Professor William Laurance, of James Cook University and the Smithsonian Tropical Research Institute in Panama, said these reserves were like arks for biodiversity.
“Even though they are our best hope to sustain tropical forests and their amazing biodiversity in perpetuity, some of the arks are in danger of sinking,” Professor Laurance said.
The researchers studied more than 30 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 populations had changed over the past two to three decades and identified environmental changes that might threaten the reserves.
Dr Baker of Monash University’s School of Biological Sciences said that while many of the reserves had provided an effective haven for flora and fauna, around half had experienced declines in biodiversity.
“This is a serious concern because many of these reserves are among the last great wild places in the tropics,” Dr Baker said.
The researchers found that on threatened reserves, an alarmingly wide range of species had declined, including big predators, primates, old-growth trees, and stream-dwelling fish and amphibians. The reserves that had suffered most were poorly protected and had suffered encroachment from illegal colonists, hunters and loggers.
Dr Baker said the degradation of areas surrounding the protected areas had negative effects on the health of the reserves themselves.
“Decline is a slippery slope. Once a reserve starts down that path, it is very hard to turn it around,” Dr Baker said.
The researchers concluded that if these arks are to withstand future threats, such as climate change, both their internal and external risks must be more effectively managed. Further, support for protected areas must be built among local communities.
“We have no choice. Tropical forests are the biologically richest real estate on the planet, and a lot of that biodiversity will vanish without good protected areas,” Professor Laurance said.