DURHAM, N.C. – Tropical moist forests are home to a majority of the Earth’s terrestrial species, yet human activities such as logging, road building and agriculture destroy between one and two million square kilometers of these vital habitats every decade.

But a new paper by a trio of 91 researchers, published this week in the Proceedings of the National Academy of Sciences, offers cause for cautious optimism – with a major caveat.

While protected areas seem to be working, there are too few of them and many, especially those in at-risk forests, are small,” says lead author Lucas Joppa, a PhD student in conservation ecology at Duke’s Nicholas School of the Environment and Earth Sciences.

Using satellite imagery and data sets from four large tropical regions, Joppa and his co-authors found that the success of national parks and other protected areas to stem deforestation hinges on both their legal designation and their inaccessibility to development. The researchers compiled satellite-derived maps of deforestation inside, or within 30 kilometers of, protected areas across four regions – the Amazon, the Congo, the South American Atlantic coast and West Africa – which once constituted about half of the world’s tropical moist forests.

By overlaying the maps of deforestation onto maps showing the boundaries of national parks, state parks, wilderness areas and other protected areas, they were able to compare patterns of deforestation and fragmentation in the four regions.  
“What is exciting is that while remote protected areas seem to be protected quite well simply because they are inaccessible, protected areas located in areas of high human pressure also seem to be maintaining their legal boundaries,” says Scott Loarie, a fellow PhD student in conservation ecology at the Nicholas School who co-authored the paper.

Joppa and Loarie wrote their paper with their faculty advisor, Stuart Pimm, Doris Duke Professor of Conservation Ecology. 

“Protected areas are a major component of conservation efforts,” Pimm explains, “and we must know if they are succeeding. By quantifying patterns of vegetation, fragmentation, and the size of these areas across regions, our study provides important insight into these vital networks of protected areas.”

Editor’s note: For helping contacting Joppa, Loarie or Pimm, contact Tim Lucas, (919) 613-8084,tdlucas@duke.edu.