Protected areas in tropical forests may not be enough on their own to safeguard local mammal species, especially when there are human settlements nearby, a new study finds.
“Wherever human pressure is high, mammal populations suffer, even in areas meant to protect them,” Michela Pacifici, a research fellow at Sapienza University of Rome, not affiliated with the study, told Mongabay in an email.
Tropical forests are among the most biodiverse ecosystems on Earth and home to many threatened mammal species. Conventional thinking has been that setting aside stretches of forests for conservation is the best way to ensure survival of most species. The authors of this study wanted to quantify the effect human presence has on protected areas, both the variety of mammal species in an area and their abundance and distribution.
So, for this study, 31 of the 37 areas sampled (84%) were under some form of protected status. The study authors used existing camera-trap data on the diversity and abundance of 239 ground-dwelling mammals on three continents. They then compared how the variety and abundance of mammals changed with distance to human settlements and the population density of those settlements.
“Their study beautifully illustrates the power of scale, bringing together data on mammal richness and occupancy from more than 2,000 sites within 37 forests,” Jonas Geldman, with the University of Copenhagen, not involved with the study, told Mongabay in an email.
The models revealed that for every 16 people per square kilometer (41 people per square mile) outside a protected area, species richness inside the area declined by 1%. Notably, in forests near human settlements, species that tolerate human activity thrived while more sensitive species disappeared entirely, leading to local extinctions.
Human populations are essentially “filtering away the most sensitive species and favoring the generalists,” Carlo Rondinini, a zoology professor with Sapienza University of Rome, not affiliated with the study, told Mongabay by email.
As the world works toward the global goal of protecting 30% of Earth’s land and water by 2030, Ilaria Greco, lead author of the study and research fellow at the University of Florence, told Mongabay that it’s not enough to just protect forests. To truly preserve mammal biodiversity, she said, conservation efforts should include buffer zones and collaboration with local communities to reduce hunting and agricultural expansion in protected forests.
“If you improve their living standards, maybe you provide alternatives to extraction from forest, then you’re actually putting aside some stress to the tropical forest,” Grecco said.
Banner imageof a jaguar in Colombia by Rhett A. Butler/Mongabay.
