You read that correctly. According to Professor Nick Haddad, the lead author of a recent study on forest fragmentation, “There are really only two big patches of intact forest left on Earth – the Amazon and the Congo.”
Haddad was part of an international team of 24 scientists that analyzed the impacts of human activity on forests across five continents. Funded by the National Science Foundation (NSF), their analysis of global forest cover was recently published in the journal Science Advances.
The team synthesized seven fragmentation experiments that spanned multiple biomes and scales over the course of 35 years and found that, due to human development (the construction of roads and structures), 70 percent of forests are now within one kilometer of the forest’s edge. According to the study, this habitat fragmentation “reduces biodiversity by 13 to 75 percent and impairs key ecosystem functions by decreasing biomass and altering nutrient cycles.”
In a statement, Haddad said that the results were “astounding.”
“Nearly 20 percent of the world’s remaining forests are the distance of a football field – or about 100 meters – away from forest edges,” he explained. “Seventy percent of forest lands are within a half-mile of forest edges. That means almost no forests can really be considered wilderness.”
The diversity of animal species within these small, isolated forests are in notable decline. Birds, in particular, suffer from a lack of true wilderness, as forests with more edges give their predators the advantage. Pollinators, too, also showed declines in productivity.
“No matter the place, habitat or species,” said study co-author Doug Levey, a program director in NSF’s Division of Environmental Biology, “habitat fragmentation has large effects, which grow worse over time.”
Sparser forests also mean a diminished capacity to absorb carbon dioxide, which could lead to an increase in atmospheric global warming.
And this problem is only growing worse. Haddad said that the trajectory of forest fragmentation “is still spiraling downward.” According to the International Energy Agency, over 15 million miles of new roads will be paved worldwide by 2050.
“Roads scare the hell out of ecologists,” William Laurance, a professor at James Cook University, told The New Yorker. “You can’t be in my line of business and not be struck by their transformative power.”