Jaguar in Brazil. A new study finds that apex predators, like the jaguar, are some of the most sensitive to environmental degradation both inside and outside tropical forest parks. Photo by: Rhett A. Butler.
Governments have set up protected areas, in part, to act as reservoirs for our Earth’s stunning biodiversity; no where is this more true than in the world’s tropical forests, which contain around half of our planet’s species. However a new study inNaturefinds that wildlife in many of the world’s rainforest parks remains imperiled by human pressures both inside and outside the reserves, threatening to undercut global conservation efforts. Looking at a representative 60 protected areas across 36 tropical nations, the scientists found that about half the parks suffered an “erosion of biodiversity” over the last 20-30 years.
“These reserves are like arks for biodiversity. But some of the arks are in danger of sinking,” said lead author, William Laurance, from James Cook University and the Smithsonian Tropical Research Institute, in a press release. “Even though they are our best hope to sustain tropical forests and their amazing biodiversity in perpetuity.”
Laurance and colleagues conducted over 200 detailed interviews to survey changes in over 30 taxonomic groups (such as plants, primates, and top predators) in the protected areas. They found that many important groups were particularly sensitive to environmental changes inside and outside the park, including most large-bodied animals; amphibians; lizards; non-venomous snakes; freshwater fish; epiphytes; old-growth trees with large seeds; and top predators. Slightly less vulnerable species included primates, some birds, poisonous snakes, and migratory animals. Other groups—such as invasive species, lianas, vines, and some butterflies—actually did better when the park’s ecosystems were degraded.
“The scariest thing about our findings 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,” Carolina Useche with the Humboldt Institute said.
The study, the most comprehensive of its kind to date, found that 80 percent of the reserves had some loss in biodiversity, with around half showing serious decline. Inside protected areas the largest indicators of biodiversity loss was declining forest cover as well as an increase in logging, hunting, or harvesting of non-timber products.
“Almost as important is what’s going on outside it,” explains Kadiri Serge Bobo of the University of Dschang. “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, fires, and hunting on a protected area’s perimeters were shown to significantly hamper biodiversity within.
“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,” Useche added.
On the plus side, the study found that good enforcement was key to better-performing protected areas.
“Reserves in which actual, on-the-ground protection efforts had increased over the past 20 to 30 years generally fared better than those in which protection had declined; a relationship that was consistent across all three of the world’s major tropical regions,” the researchers write.
The best reserves, however, must also creatively counter threats at the park’s edges. To do this, the scientists recommend establishing buffer zones around existing parks, creating corridors to connect parks, and working with locals to promote lower-impact activities.
“A focus on managing both external and internal threats should also increase the resilience of biodiversity in reserves to potentially serious climatic change,” the authors write.
More and smarter management efforts are needed if tropical forest parks are serve as biodiversity arks in an age of mass deforestation and climate change. The stakes are high: given that the world’s rainforests contain so many species, if their protected areas falter, mass extinction will be inevitable.
CITATION: Laurance, William F., and 215 coauthors. 2012. Averting biodiversity collapse in tropical forest protected areas. Nature, DOI:10.1038/nature11318.
Forest clearing for an oil palm plantation at the edge of Gunung Leuser National Park in Sumatra. New research shows that forest loss on park edges can hugely impact biodiversity within. Photo by: Rhett A. Butler.
July 25, 2012