Expanding the planet's protected natural areas to safeguard vanishing forests and other ecosystems, and the species they protect, is unlikely to be effective on its own as human encroachment into reserves grows, scientists warned Tuesday.
A study by Cambridge University researchers, which looked at thousands of conservation areas in more than 150 countries, found that, on average, protected designation is not reducing human encroachment in vulnerable areas.
Both chronic underfunding of efforts to protect the land, and a lack of engagement with local communities that live there are hurting conservation efforts, they found.
Creating protected areas is "a type of intervention that we know can work, we know is absolutely essential for conserving biodiversity, at a time in this world's history where it has never been under higher pressure," said lead author Jonas Geldmann.
"But despite that we are seeing that some of our protected areas are not managing to mitigate or stop that increasing pressure," said Geldmann, of the University of Cambridge Conservation Research Institute.
One-sixth of the globe now falls within protected areas, the study noted. Those include national parks, nature reserves and wilderness areas, according to the International Union for Conservation of Nature's World Database on Protected Areas.
Such protected areas are vital for preserving diverse ecosystems, and helping to curb climate change by conserving carbon-sequestering forests and other vegetation.
The United Nations Environment Program estimates protected areas hold 15% of the carbon stored on land.
"Protected areas are one of the most important things that we can do to stem the loss of biodiversity and to help solve the climate crisis," said Andrew Wetzler, managing director of the U.S.-based Natural Resources Defense Council's nature program. "The destruction of natural habitat is the single biggest driver of extinction."
Cambridge researchers said their analysis is by far the largest of its kind.
From lights to crops
Scientists examined over 12,000 protected areas between 1995 and 2010, using census and crop yield data as well as satellite evidence of agriculture and lighting at night to assess human encroachment.
The majority of protected areas in every global region saw increased human activity. However, researchers said encroachment appeared more serious in nations with fewer roads and a lower rank on the Human Development Index.
Across the northern hemisphere and Australia, protected status on average proved effective at slowing encroachment when compared with equivalent unprotected habitats.
But in particularly biodiverse regions such as South America, sub-Saharan Africa and southeast Asia, pressure from human activity inside protected areas was significantly higher.
The study found agriculture is a major driving force behind human encroachment in protected areas.
African mangrove forest reserves, for instance, saw 13% greater losses to agriculture than unprotected mangrove areas between 1995 and 2010, the study found.
"Because (protected areas) are supporting biodiversity, they are more likely to support a high agricultural yield," Geldmann said. To farmers, "they are actually more attractive than the outside areas."
In order to safeguard protected areas, experts emphasized the need for governments to allocate additional resources.
"Simply designating a place as protected can't be the beginning and the end of a conservation effort," Wetzler said. "We need to make sure protected areas are appropriately funded."
Consulting local communities and involving them with conservation efforts also is key, the experts said.
"We've seen from other studies that if you don't engage with the people living in and around the protected areas, if they're not partners to the protected areas, then making (reserves) work is much more difficult," Geldmann said.
Local communities are too often left out of conversations about a protected area's importance and upkeep, he said.
"But when you start engaging them, there's often a lot of value to be had for local communities as well as for biodiversity."