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Forest fragmentation hits wildlife hardest in the tropics

06 Dec 2019

Human development, land conversion, fire and storms are causing the forests worldwide to become increasingly fragmented, to the degree that 70% of the Earth’s remaining forest is within 1 kilometre of a forest edge today. The world’s most intact forest landscapes are found in the tropics, but fragmentation of tropical forests is predicted to accelerate over the next decades.

In the face of this reality, researchers are trying to understand how to make best use of the remaining intact habitat for the purpose of wildlife conservation. In a study published in Science today, ASE Asst Prof Eleanor Slade and co-authors shed some light on this issue: “Everyone knows habitat loss is bad for animals, but there’s been a longstanding debate about fragmentation – the arrangement of remaining habitat,” said co-corresponding author Matt Betts, a professor in the OSU College of Forestry and the director of the Forest Biodiversity Research Network. “How do we design wildlife reserves? Do we make many small ones, or fewer big ones, or do we make corridors?”

The study looked at over 6,500 animal species globally and found that tropical animals are particularly dependent on large areas of continuous, unfragmented forest landscape. Tropical animals are as much as six times more vulnerable to disturbance, and it is a historic legacy of low disturbance in tropical rainforests that have resulted in species being less adapted to changing environmental conditions. “Biodiversity of vertebrates increases massively toward the equator, but even accounting for that, a greater proportion of species are more sensitive to fragmentation,” Betts said. “Sensitivity increases six-fold at low versus high latitudes. That means that not only should we care about the tropics because so many species are found there that are found nowhere else on Earth, but those species are also more sensitive to how we treat the forests.”

At higher latitudes, for example in temperate forests, a larger proportion of animals can tolerate significant changes in the landscape, due to having evolved through glaciations, frequent wildfire, hurricanes etc. This does not mean that temperate forests are not sensitive to fragmentation, but the consequences for wildlife are less severe compared to tropical forests.

The study has implications for the formation of reserves, while in temperate forests the configuration patterns of preserved forest is less important than preserving the right kind of habitat, in tropical forests preserving continuous areas of unfragmented forest landscape is more important.

Read the original article: Extinction filters mediate the global effects of habitat fragmentation on animals

Commentary in The New York TimesFractured Forests Are Endangering Wildlife, Scientists Find

Perspective in ScienceLasting signature of forest fragmentation