Can protected tropical forest reserves prevent a biodiversity collapse?


Conservation efforts need to expand beyond parks to include surrounding landscapes

Many of the world’s tropical protected areas are struggling to sustain their biodiversity, despite the recognition that these parks and reserves are the biologically richest ecosystems on earth, according to a study published in the journal Nature by more than 200 international scientists, including Prof. Colin Chapman of McGill University.

“Reserves are like arks for biodiversity, but some of the arks are in danger of sinking, even though they are our best hope to sustain tropical forests and their amazing biodiversity in perpetuity,” says lead author Prof. William Laurance, of James Cook University in Cairns, Australia, and the Smithsonian Tropical Research Institute in Panama.

Prof. 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.

“Our research is particularly alarming because the conservation community has relied on parks and reserves as the primary tool to protect the biodiversity of the tropics. The scale of the threat is highlighted by the fact that the only primate species that is believed to have gone extinct in the 20th century did so despite occurring in large national parks,” says McGill professor Colin Chapman, Canada Research Chair in Primate Ecology and Conservation at the Department of Anthropology & School of Environment, and study co-author.

While most reserves were helping to protect their forests, about half were struggling to sustain their original biodiversity. “The scariest thing about our findings,” says 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.” 

The declines 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 faced encroachment from illegal colonists, hunters and loggers. Eighty-five percent of the reserves studied lost some nearby forest cover over the past two to three decades, and 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 concluded that 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. This is particularly alarming because the most endangered species are found in protected areas occurring in highly degraded landscapes, which implies that we may be facing a wave of extinctions in the near future.

The authors conclude that a better job needs to be done in protecting the protected areas - by 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,” says 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.”

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Cynthia Lee
McGill University
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