The Eurasian beaver is one of 20 species that, if reintroduced, can have a significant impact on the restoration of the world’s ecosystems. Credit: WildMedia / Shutterstock
The return of beavers, bears and bison around the world can significantly improve the state of the world’s ecosystems.
A report funded by the United Nations found that the return of large mammals could strengthen the health of the natural world, combat climate change and biodiversity loss in the process.
Reintroduction of only 20 species of large mammals could help restore biodiversity in the world.
The return of these animals to their historical habitats around the world could create the conditions necessary to allow these species to expand their range to cover more than a quarter of the planet. This would help recover ecosystemsto close excess carbon dioxide and increase populations of other species.
Lead author Dr Carly Wynn says: “Our results provide both hope and an opportunity to reverse the depletion of pristine fauna groups through active, strategically implemented recovery programs.
“We are seeing real funding and focus on restoring ecosystems and nature-based solutions. We must also ensure that conservation and restoration efforts bring diversity and richness to life on Earth, and help restore the full grouping of natural-present species.”
The analysis, conducted on behalf of the United Nations Environment Program (UNEP) and the non-profit organization RESOLVE, was published in the journal Ecography.
What is raiding?
Reintroduction of large mammals into their historical habitats is common aspect of rewildingwhere attempts are made to restore ecosystems to a “natural” state that can regulate itself.

Gray wolves, reintroduced to Yellowstone National Park, USA, have helped control herbivorous populations. Credit: Holly Kuchera / Shutterstock
Opinion on what time period the ecosystem is considered “natural” varies. Some believe the historical base is around 1500 AD, while others are in favor of restoring ecosystems to a state similar to what they were in the last ice age more than 12,000 years ago.
While railing provides an opportunity to improve biodiversity and the functioning of ecosystems, it also has its drawbacks. Conditions for some ecosystems simply do not exist. In addition, the introduction of large animals may pose a threat to humans and animals.
This applies to predatory mammals such as wolves, the reintroduction of which is often controversial among some. However, studies show that these animals have a significant impact to the environment through the control of herbivorous populations, allowing plants and cattle to thrive.
In addition to carnivores, reintroduction of herbivores can also have a significant impact through seed dispersal, nutrient processing and assistance in control the fire by grazing.
The researchers behind the current study wanted to investigate where reintroduction of large mammals would have the greatest impact and how this could be achieved. They found that only 20 key species, including 13 herbivores and seven predators, are needed to restore biodiversity worldwide.
Study of ecoregions
To assess the state of ecosystems around the world, researchers have divided the planet into ecoregions, or areas containing different natural communities. The number of large mammals in each was noted and compared with historical records.
The analysis showed that only about 6% of the study sites had similar large mammalian communities as 500 years ago. Overall, currently about 16% of the Earth’s surface contains mammalian communities at any level of virginity.
The researchers then looked at which ecoregions were best suited for recovery. Much of northern Asia, northern Canada, and parts of South America and Africa have been recognized as the most suitable, and only a few large mammals are required to restore these ecosystems.

The Gazelle lady is threatened with extinction as a result of hunting and habitat destruction. Credit: photo kingma / Shutterstock
In Europe, the reintroduction and conservation of animals such as c Eurasian beaverEuropean bison and wolves have been found to help expand large mammal populations back to the 35 regions from which they were lost.
Similar steps for species such as the hippopotamus, cheetah and lion in Africa could more than double the area of the continent inhabited by healthy mammal populations.
In addition to changing the environment in a way that benefits other species, reintroducing some of these animals will also help preserve them.
For example, one of the 20 species that is projected to have the greatest impact in the case of re-introduction is the gazelle lady. But these animals, originally from the Sahara, are themselves Endangered there are only 200 adults left in the world.
Scientists, however, recognize that many changes are needed before reintroduction can begin. For example, the factors that caused it large mammals to become a threat in the first place, such as hunting and habitat loss, would need to be brought under control.
Many ecoregions also cover national borders, and international cooperation will be needed to return the animals.
The results of this study merge into an ongoing conversation about the importance of biodiversity ahead of the COP15 conference to be held in China later this year.
Joe Gosling of UNEP acknowledges that there is work to be done, but says action is possible with a concerted effort.
“Our recommendations may not yet be relevant everywhere in the field – local assessments will judge whether, for example, hunting pressures or a lack of a proper production base mean other issues that need to be addressed before starting a reintroduction program,” he said. “However, our findings show that there are vast areas in the world that may be suitable for the recovery of large mammals if mitigation factors are driven.
“We are now in a critical decade for nature: the UN Decade for Ecosystem Restoration. The next priority step will be to restore the big ones mammals population as a clear ambition at the international and national levels. Extensive, effective nature restoration will be impossible without the support of governments backed by key conservationists and sponsors. ”
Carly Vynne et al., An Ecoregional Approach to Restoring Untouched Groups of Major Mammals in the World, Ecography (2022). DOI: 10.1111 / ecog.06098
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Museum of Natural History
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