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Africa’s ecosystems have lost over a third of the energy they once had, with far-reaching impacts on biodiversity and human livelihoods.

Observations across the continent show that the total ecological energy flowing through Africa’s wildlife has declined by more than one-third since pre-colonial times. Large-bodied species such as elephants, rhinos, and lions, which shape the environment through their movement and feeding, have suffered the most dramatic losses.

The new research, and worked on by Imperial and researchers, has emphasised the scale of the problem and its implications for ecosystem restoration and policy.

, lead author of the study and a researcher at the , said: "The most important, and alarming, result is the collapse of ecosystem functions performed by Africa’s megafauna. Large wild animals are ecological engineers. Their roles can’t simply be replaced by smaller species or livestock. The loss of these giants has the potential to transform Africa’s ecosystems and landscapes."

Measuring ecosystem 'power'

Our work shows that the decline in large wildlife is not just a numbers issue, it’s also a loss of the energy that drives and sustains ecosystem functions. By looking at energy flows, we can identify conservation actions critical for maintaining resilient landscapes. Professor Joe Tobias Professor of Biodiversity and Ecosystems

The study uses an ‘ecosystem energetics’ framework to quantify how energy moves through food webs, from sunlight captured by plants to the animals that feed on them. By combining multiple ecological datasets covering over 3,000 species and 317,000 landscapes across forests, savannas, and deserts, the team calculated how much natural energy flows through the continent’s wildlife today.

Smaller animals such as rodents and songbirds now dominate much of the remaining energy flow, but they cannot replace the ecological roles of Africa’s megafauna.

, from Imperial’s Department of Life Sciences at Silwood Park, said: ‘Our work shows that the decline in large wildlife is not just a numbers issue, it’s also a loss of the energy that drives and sustains ecosystem functions. By looking at energy flows, we can identify conservation actions critical for maintaining resilient landscapes.’

A roadmap for restoration and policy

Beyond diagnosing decline, the energy-based framework provides practical guidance for conservation. Restoration programmes can prioritise returning the ecological functions of species, not just the species themselves. This is vital for ensuring landscapes remain productive and resilient, supporting both biodiversity and human communities.

The approach also has global significance. By linking species loss directly to the planet’s ability to cycle nutrients, water, and carbon, energy-based metrics could help refine international biodiversity targets and inform policies under frameworks such as the Kunming–Montreal Global Biodiversity Framework.

A warning and an opportunity

The researchers emphasise that while the decline in wildlife ‘power’ is alarming, it also provides a tangible way to monitor recovery. By tracking energy flow in ecosystems, scientists, governments, and conservationists can better understand how interventions translate into functional restoration.

This research underscores the urgency of protecting and restoring wildlife, not only for the survival of iconic species but for the ecological health of the entire planet.

Publication details

‘’ is published in Nature. DOI: 10.1038/s41586-025-09660-1.