Rewilding isn’t just about the animals

As this year kicks off the “Decade on Ecosystem Restoration” to try and repair some of the damage caused by humans, scientists shine the spotlight on rewilding, a process of rebuilding ecosystems.

Previous research has made it clear that rewilding is a complex process with many interlocking considerations. Now, a team from The Netherlands adds a new one to the mix: geodiversity.  

It is important to consider a region’s geography and geology when choosing where to rewild, says Kenneth Rijskijk from the University of Amsterdam. His team argues that these factors could ultimately determine how successful rewilding is.

“Clearly, we cannot, and should not, rewild everywhere,” says Rijskijk. “It makes sense to pick out specific areas where rewilding is more likely to succeed, taking into account how landscape features, like ruggedness and soil nutrients, can shape ecosystems.”

Pups from the 8-mile wolf pack in yellowstone national park are shown gathered on an outcrop
The mid-1990s reintroduction of wolves to Yellowstone, where they were once eradicated, is one of the success stories of rewilding. In this photo from 2013, pups from the 8-Mile wolf pack are shown gathered on an outcrop. Credit: U.S. National Park Service via Flickr

Current rewilding evaluations use biodiversity metrics such as increased abundance and diversity of plant or bird species, without considering geodiversity.

“It’s remarkable that, from a conservation standpoint, the landscape itself is significantly undervalued in the success of rewilding projects,” says co-author Harry Seijmonsbergen.

Take famous success stories such as the Yellowstone National Park reintroduction of apex predators – grey wolves – in the US and The Netherland’s Oostvaardersplassen nature reserve, for instance.

What the researchers say has been overlooked is the differences in landscapes: Yellowstone’s mountainous terrain versus the flat, man-made marshlands of the Oostvaardersplassen, where domestic herbivores such as red deer and horses roam freely.

By investigating how interactions between large herbivores and predators influence the landscape, the team found that geodiversity depends largely on the number of large herbivores.

“More grazers, for example, result in lower diversity of vegetation structural types, more compacted soils and increased erosion,” they write, explaining that this could have multiple impacts on geodiversity, in turn affecting the way herbivores interact with the environment.

“For example, a topographically diverse landscape may host localities to shelter against harsh weather conditions, and function as safe spots against predators.”

The team created a geodiversity index to help conservation biologists measure landscape quality and predict the outcomes of rewilding reserves, using satellite, aerial and field data that factors in geomorphology, topography and soil diversity.

The landscape quality score includes features such as elevation, forested areas, openness and quietness, which they compared with an independent ecological index and applied to 12 possible rewilding sites identified in north-western Europe.

The researchers are presenting their findings at the EGU General Assembly 2021.

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