Squeeze anything hard enough and something has to give—even to the point of collapse. Protected areas, which are a cornerstone of our efforts to conserve nature, are no different.
All around the world, protected areas are under tremendous pressure—not just from poachers and encroachers inside the reserves, but also by destructive forces immediately outside them.
For example, the iconic Serengeti-Mara ecosystem in East Africa, a protected area the size of Switzerland, sustains the world’s largest migration of land animals. But new research shows that the margins of the Serengeti-Mara are being squeezed by overgrazing of livestock, soaring human populations, and cropping.
As a result, wildlife have been compressed into the core of Serengeti-Mara or into intensively managed parts of it, such as the World Heritage Ngorongoro Crater.
Like falling dominos, these squeezing effects affect not just wildlife but also a range of ecosystem processes. In the Serengeti-Mara, the last domino to fall is the palatable grass itself—the basis of the ecosystem’s food chain. Ripped out by starving wildlife, the severed roots destroy the ability of grass to absorb nutrients from the soil.
In the Amazon basin, around 2 million hectares of forest are cleared or fragmented annually. The edges of forest fragments can be squeezed to the point of implosion by microclimatic stresses and wind shear, which kill many trees and make the forest much more vulnerable to destructive fires.
Such fires can penetrate at least 2.5 kilometers in from the edges, opening the rainforest to invasion by fire-loving weeds and grass.
While 20 percent of the Amazon has been deforested, around 50 percent is being squeezed by edge effects. The crushing endpoint is a landscape of fire-dominated savannah and scrubby vegetation.
In many landscapes, as much biodiversity occurs outside protected areas as inside them. In Equatorial Africa, for instance, some protected areas are embedded within relatively intact forests. These areas outside reserves currently harbor three-quarters of all gorillas.
But a lack of park-guards, ebola outbreaks, proliferating roads and poaching, and intensive logging are all taking their tolls on the forests and wildlife. Gorillas are declining precipitously, with populations crashing by 80 percent since the 1950s.
A study led by ALERT director Bill Laurance showed that, across the tropics, biodiversity declines inside protected areas are often driven in part by environmental threats, such as deforestation and fires, occurring outside the protected areas.
Thus, the fate of our protected areas depends not only on protecting them but also limiting destructive changes in the habitats that immediately surround them. To quote the famed ecologist Daniel Janzen, “No park is an island.”
We Know What to Do
The management of protected areas and their critical surrounding habitats is a massive challenge.
A recent paper shows that biodiversity loss can be predicted from conservation spending. Sixty per cent of global biodiversity declines occurred in only seven countries. Beginning with the worst, they are Indonesia, Australia, USA (mainly Hawaii), Malaysia, China, Papua New Guinea, and India.
The good news is that we know how to save nature. Regional- and landscape-scale approaches to protect ecosystems are well established. And there’s no need to delay—these principles can be put in place right now.
But to ensure the survival of nature, we must reduce the pressures that plague so many of our reserves. It’s not just about protecting protected areas, but also sparing the lands immediately around them from “the big squeeze.”