Forests are the metropolises of the animal kingdom, housing mammals, birds, reptiles, and more. Unsurprisingly, the ever-expanding nature of human development means that these leafy worlds are becoming increasingly fragmented.
A new paper published in Nature shows that 85% of forest-dwelling vertebrates have been affected by our encroachment. Around half of the world’s forests are now 500 metres from the edge because of human activity such as logging, mining, agriculture, poaching, and infrastructure.
The international team of researchers analyzed over 1,500 species from all over the world to see how they react and deal with forest edges in 22 different landscapes.
The results showed that those who prefer forest edges win out, while creatures dependent on the forest core are at risk. Forest edges have less moisture, more light, higher temperatures, and more exposure, and these features allow some creatures to thrive while others struggle.
Rapid environmental shifts create winners and losers in the ecosystem
Newly created forest edges instigate a stark ecological shift as creatures move to another part of the forest or die out, while others find a new home at the edge.
“About half of species win from the forest change; they like the edges and so avoid the deep forest, preferring instead to live near forest edges,” says Robert Ewers of Imperial College, London.
“The other half lose; they don’t like the edges and instead hide away in the deep forest. The winners and losers aren’t equal though. Some of the species that like edges are invasive like the boa constrictor, while the ones huddled into the deep forest are more likely to be threatened with extinction, like the Sunda pangolin.”
An Environment Canada report previously found that 5% of undisturbed Canadian forest was lost between 2000 and 2013, with 60% of that loss coming from Alberta, Ontario and Quebec. Boreal caribou, cougars, and wolves are examples of at-risk Canadian wildlife affected by fragmentation.
Caribou are especially vulnerable; they depend on high-elevation old growth for protection from predators and food during most times of the year.
Lead author Dr. Marion Pfeifer commented that the study “is useful for land management and as a tool to help guide our conservation efforts. The next step is to use this data and our software to allow managers to create ‘optimal landscapes’ that combine forest use with biodiversity conservation.”