A team of Smithsonian scientists joined more than 200 others around the world to examine if giving protected status to a tropical forest offered adequate protection to the plants and animals within its borders. They found that in almost half the cases it did not. The team's findings are published online in the scientific journal Nature.
The scientists conducted a comprehensive assessment of long-term changes within 60 protected forests across the world's major tropical regions. They studied more than 30 different categories of species—from trees and butterflies to primates and large predators—within protected areas in 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 around the reserves.
They found that about half of these forest reserves have been effective to varying degrees in protecting its resident species. However, the remaining reserves are experiencing what the scientists term an erosion of biodiversity, and it is likely due to outside influences.
Our findings suggest that tropical protected areas are often intimately linked ecologically to the areas surrounding them, said John Seidensticker, co-author of the research and conservation scientist at the Smithsonian Conservation Biology Institute. A protected forest's borders mean nothing to the sound and pollution of construction, diseases that travel by air and water or invasive species that go unchecked.
Seidensticker was one of nine Smithsonian scientists involved in the project from three separate science units at the Institution: the National Museum of Natural History, the Smithsonian Conservation Biology Institute/National Zoo and the Smithsonian Tropical Research Institute.
Some of the major threats to the biodiversity within the forest reserves studied were the encroachment of non-native plant and animal species, the introduction of human diseases and illegal hunting and logging.
The scientific team highlights the vital ecological functions of wildlife habitats not only within protected forests, but also those surrounding them. The creation of buffer zones around reserves and lower-impact land use near them will strengthen the protection within the reserves and increase the resilience of its biodiversity to threats in the future.