Every terrestrial ecosystem has its own “natural energy” that powers vital ecological functions such as nutrient cycling and seed dispersal.

A new study conducted by the University of Oxford in collaboration with Sapienza University of Rome introduced a new approach based on “ecosystem energetics”, which quantified the natural energy loss of African wildlife.

The results, published in the scientific journal Nature, showed that, compared to pre-colonial times, the overall natural energy of the African continent has decreased by more than a third due to the decline of large species such as elephants, rhinos and lions, which shaped and regulated the ecosystem in the past. In this sense, large wild animals are true ecological engineers that cannot simply be replaced by smaller species or livestock.

“The research shows that the reduction in energy flow through bird and mammal communities has not been uniform, but has differentially affected functional groups that support essential ecosystem processes such as seed dispersal, pollination and vegetation modelling,” says Luca Santini of Sapienza University of Rome, co-author of the study.

Based on data from over 3,000 species of birds and mammals distributed across 317,000 landscapes including forests, savannahs and deserts, researchers combined six large ecological datasets, including a new Biodiversity Integrity Index for Africa, built with the contribution of local experts.

This energy point of view reveals not only how much biodiversity has been lost, but also how this loss affects the very functioning of nature. While large mammals have suffered the most severe declines, smaller species – such as rodents and songbirds – now dominate the continent's residual energy flows.

In addition to diagnosing the decline of African bird and mammal communities, the study also proposes the use of an “energy” approach to inform ecological restoration projects. Mapping energy flows allows the integrity of species groups that perform important ecosystem functions to be quantified, thereby identifying restoration priorities that are independent of specific composition.

This research could redefine how scientists and policymakers assess biodiversity loss around the world, as the fate of individual species is linked to the functioning and stability of the entire planet.

References: Energy flows reveal declining ecosystem functions by animals across Africa

Ty Loft, Imma Oliveras Menor, Nicola Stevens, Robert Beyer, Hayley S. Clements, Luca Santini, Seth Thomas, Joseph A. Tobias & Yadvinder Malhi - Nature (2025) DOI: 10.1038/s41586-025-09660-1