Reintroducing large mammals could restore global ecosystems

Explore ecoregions

To assess the state of the world’s ecosystems, researchers have divided the planet into ecoregions, or areas containing distinct natural communities. The number of large mammals in each was noted and compared to historical records.

The analysis revealed that only about 6% of the places surveyed had large mammal communities similar to those of 500 years ago. Overall, currently about 16% of the Earth’s surface contains mammalian communities at any level of integrity.

The researchers then looked at which ecoregions were best placed to be restored. Most of northern Asia, northern Canada, as well as parts of South America and Africa were found to be the most suitable, with only a few large mammals needed to bring these ecosystems back to their original state. previous state.

In Europe, the reintroduction and conservation of animals such as the Eurasian beaver, European bison and wolf have helped to expand populations of large mammals into 35 regions from where they have been lost.

Similar measures for species such as hippopotamus, cheetah and lion in Africa could more than double the area of ​​the continent in which healthy mammal populations live.

In addition to changing the environment in a way that benefits other species, reintroducing some of these animals would also contribute to their conservation.

For example, one of the 20 species predicted to have the most impact if reintroduced is the dama gazelle. But these animals, native to the Sahara, are themselves critically endangered with just 200 adults left in the world.

Scientists recognize, however, that many changes are needed before reintroductions can begin. For example, factors that threatened large mammals in the first place, such as hunting and habitat loss, should be brought under control.

Many ecoregions also cross national borders and would therefore require international cooperation if animals were to be brought back.

The findings of this study feed into an ongoing conversation about the importance of biodiversity in the run-up to the COP15 conference, to be held in China later this year.

UNEP’s Joe Gosling conceded there is work to be done but said action is possible with concerted effort.

“Our recommendations may not be suitable everywhere in the field at this time – local assessments will help to judge whether, for example, hunting pressures or the lack of an adequate prey base mean that other problems need to be resolved before starting a reintroduction programme,” he says. “However, our findings show that there are large areas of the world that could be suitable for large mammal restoration if mitigating factors are managed.

“We are now in a critical decade for nature: the United Nations Decade of Ecosystem Restoration. A next priority step would be to consider the restoration of large mammal populations as an explicit ambition at international and national levels. Widespread and effective nature restoration will not be possible without buy-in from governments, supported by key conservation actors and donors.