Large herbivores must be restored to balance ecosystems •

Ecosystems structured around the relationship between animals and the plants they eat are becoming unbalanced with the disappearance of large herbivores. A new study has found that there are not enough large wild herbivores left on our planet for these ecosystems to function properly.

“Large herbivores provide key ecosystem processes, but have suffered massive historical losses and are under intense pressure, leaving current ecosystems with faunas greatly simplified from the long-term evolutionary norm,” the authors of the study.

Although June 2021 saw the start of the United Nations Decade of Ecosystem Restoration, with 115 countries pledging to restore up to one billion hectares of nature worldwide, one of the biggest challenges will be to discover what levels of restoration of herbivores will be necessary for a balanced functioning of ecosystems.

In order to answer this question, a research team led by the University of Aarhus and the University of Sussex calculated a baseline for large animals based on the ratio of producers to consumers (i.e. i.e. plants and herbivores) in nature reserves in Africa. According to the researchers, a close correspondence between large herbivores and the amount of plants they can eat currently only exists in Africa.

“African ecosystems have a species-rich mammalian fauna and a large biomass of large herbivores that are significantly related to plant productivity,” explained the study’s lead author, Camilla Fløjgaard, an ecologist at the University of ‘Arhus. “But we can’t find this pattern on other continents, and in general the biomass of large herbivores is much lower than we would expect given the level of productivity.”

By analyzing data from natural areas, as well as several protected areas, reserves and rewilding projects in Europe, scientists found that the biomass of large herbivores in natural areas was less than a tenth of the biomass found in forest areas. fenced rewilding with restored areas. herbivorous fauna.

“Interestingly, even in many protected areas, the numbers of large herbivores are only a fraction of what the areas can actually support,” Fløjgaard said.

In order to restore the stability and biodiversity of many ecosystems around the world, efforts to increase populations of wild herbivores are urgently needed.

“Bringing back large animals is crucial to restoring self-sustaining ecosystems and conserving biodiversity, but it won’t be easy,” said study co-author Rasmus Ejrnæs, senior researcher at Aarhus University. “Big animals are troublesome because they damage crops, disrupt traffic and generally get in the way. This will require political commitment and careful physical planning, including fenced reserves.

The study is published in the Journal of Applied Ecology.

Through Andrei Ionescu, Personal editor