Sub-Saharan Africa lost 24% of its biodiversity since pre-industrial times, says study

Sub-Saharan Africa, the part of Africa south of the Sahara, has lost 24 per cent of its biodiversity since pre-industrial times, according to a new study.

Biodiversity is an integral part of sustainable development. One major limitation to achieving conservation goals is the lack of information on the impacts of diverse human activities on biodiversity and resulting ecosystem functions and services.

To overcome critical data gaps and limitations of top-down biodiversity models, the study undertook a comprehensive assessment of the Biodiversity Intactness Index of Africa (bii4africa) using place-based knowledge of 200 African biodiversity experts.

The Biodiversity Intactness Index (BII) is a simple and practical tool that bridges the gap between biodiversity experts and decision-makers.

Biodiversity intactness of the region

Sub-Saharan Africa has a current estimated biodiversity intactness of 76 per cent. This means that indigenous vertebrate and plant populations across the region have on average declined to 76 per cent of their intact reference abundances.

According to the study, sub-Saharan Africa has lost just under a quarter of its pre-industrial biodiversity intactness.

Losses vary widely from under 20 per cent for disturbance-adapted herbaceous plants to as high as 80 per cent for certain large mammals.

The study identifies Rwanda and Nigeria as the least intact, with biodiversity levels below 55 per cent. In contrast, Namibia and Botswana remain the most intact, with levels above 85 per cent.

More than 80 per cent of the remaining wild organisms in the region persist in unprotected and largely untransformed natural forests and rangelands where people coexist with and depend on biodiversity. Conserving and restoring biodiversity, while working towards just and sustainable development, requires a focus on these working lands that sustain more than 500 million people.  

The study shows that the drivers of biodiversity loss differ across ecosystems.

In grasslands and fynbos (Mediterranean-type ecosystems), biodiversity loss is linked to land being converted for farming. Forest regions face mostly non-agricultural forms of degradation, while savannas experience a combination of both pressures.

The study finds that biodiversity intactness of the high-yielding intensive croplands in this region, most of which lie in the grasslands is notably less than its least-intensive, smallholder croplands that are more common in the savannas. These trends have stark implications given that cropland is projected to double and cereal demand to triple in sub-Saharan Africa by 2050. This increase will probably entail significant changes to current agricultural practices in a region where 75 per cent of the cropland comprises smallholder farming, which have some of the lowest crop yields in the world.

Central African countries retain some of the highest levels of intactness due to the persistence of humid forests, while West Africa shows low intactness due to severe degradation of forests and savannas from overharvesting and agricultural expansion.

This assessment provides decision-makers with multifaceted, contextually appropriate and policy-relevant information on the state of biodiversity in an understudied region of the world.

The study published in the journal Nature on December 3, 2025.