The extinction of animals due to habitat destruction is underestimated, says a study. However, the results could help protect species.

“Forest island” in Brazil resulting from deforestation: biodiversity has a hard time here Photo: Mateus Dantas de Paula

Species extinction is occurring even more rapidly than previously thought, especially in isolated habitats such as forest sections. This is the result of a study published on Wednesday in the specialist magazine Nature appeared. The meta-study of 123 research projects suggests that current prediction models simplify too much – and often even underestimate the loss of species due to clearing, fires, draining or other so-called habitat destruction.

This also applies, for example, to the much-cited 2019 World Biodiversity Council report, explains Jonathan Chase, one of the authors. “This is because we have so far had no solid evidence of how bad habitat destruction is across different ecosystems and species,” continues the head of the biodiversity synthesis research group at the iDiv research center.

There are two competing approaches to determining species extinction due to habitat destruction. The passive-sampling-Hypothesis assumes a simple, linear development: the more habitat is destroyed, the more species disappear.

The eco­system-decayThe hypothesis, on the other hand, claims that habitat islands – rainforest remains surrounded by fields or real islands in reservoirs – have different dynamics than large habitats. For example, some species need extensive biotopes to feel good. This thesis is not new, and there have already been studies that support it – on a small scale. But now the team of five researchers was able to validate evidence for the ecosystem-decay– Show hypothesis.

Years of data research

In many cases, the necessary information on the biodiversity of plants, birds, bats, frogs or insects could not be found in previously published studies. “We have often contacted the authors. Many of them really did everything possible to help us: be it to get old notebooks out of field work, to crack software versions or hardware that had long since expired, ”says Chase. Years passed until everything was collected.

Despite the dramatic results, the study author: optimism on the inside. A partial result is that the decline in species also depends on what is exactly around the Habitat Islands. If it was “bird- or bee-friendly agriculture, the local loss of species was lower,” explains co-author Felix May. Co-author Tiffany Knight adds: “What surprised us was that the decay of ecosystems in the Studies from Europe were less pronounced where habitats were often lost hundreds of years ago. “

For Josef Settele from the Helmholtz Center for Environmental Research in Halle, this ultimately fits into the picture: “In areas where habitat loss was not so extreme and slow, animals and plants have more time to adapt or immigrate.” The biologist agrees the author of the study that the results can be used politically to emphasize demands, for example, for biotope networks and the preservation of biological diversity as a whole.

The call for less simplification in the prediction of species extinction also affects Settele, who is co-chair of the report of the World Biodiversity Council. Its estimates that around a million species worldwide are threatened with extinction have been criticized more than alarmistly. “Now we know that we were even too careful,” said Settele.