A place-based assessment of biodiversity intactness in sub-Saharan Africa
Summary
This study maps biodiversity intactness across sub-Saharan Africa using a bottom-up, place-based Biodiversity Intactness Index (BII) built from the expert-led bii4africa dataset. The authors combined intactness estimates from 200 regional experts with species‑range and land‑use maps (including land‑use intensity) to produce spatially explicit BII scores for plants and vertebrates at policy‑relevant scales. The regional average BII is 76% (±14%), indicating an average decline to 76% of pre‑industrial (reference) population abundances. Losses are greatest among large mammals and in intensive croplands and transformed rangelands; the bulk of remaining biodiversity, however, persists in unprotected, largely untransformed working lands where people depend on nature.
Author note
Punchy take: this isn’t just another map — it’s a regional, expert‑driven reality check that corrects some misleading global model outputs and gives policymakers a locally credible tool to prioritise action.
Key Points
- Regional BII for sub‑Saharan Africa is estimated at 76% (±14%), meaning roughly one quarter of pre‑industrial biodiversity intactness has been lost on average.
- Vertebrates average 71% (±9%) intactness; vascular plants average 79% (±17%). Mammals — especially large herbivores and carnivores — show the largest declines.
- Country variation is large: Namibia and Botswana score highest (~87%), while Rwanda (48%) and Nigeria (53%) are among the lowest.
- Most remaining intact biodiversity (≈84%) exists in unprotected, largely untransformed lands that cover 80% of the region; protected areas are limited in extent and account for <10% of remaining BII.
- Croplands and intensive land‑use substantially reduce BII: high‑intensity croplands average ~26% intactness vs ~54% in low‑intensity smallholder systems; high‑intensity rangelands average ~51% vs ~85% in near‑natural rangelands.
- The approach uses structured expert elicitation (200 experts) to generate the bii4africa intactness scores and maps BII at 1×1 km and 8×8 km resolutions, with code and data publicly available.
- Validation shows expected correlations with human‑pressure indices (Human Footprint, Biomass Modification, Biodiversity Habitat Index) and with IUCN Red List threat categories, though uncertainties and potential expert biases remain.
Context and relevance
Why this matters: global models can misclassify African land‑uses (for example, planted pasture versus natural rangeland), producing policy‑relevant errors. This place‑based BII fills critical knowledge gaps for the Global South by incorporating local expertise and land‑use intensity, aligning with multilateral reporting needs (GBF) and planetary‑boundary discussions. The findings are directly relevant to national planning, conservation prioritisation, agricultural policy and initiatives on protected areas, sustainable rangeland management and agroecological transformations as cropland area and food demand rise sharply by 2050.
Why should I read this?
Got two minutes? Read this if you want the real picture of where nature is holding up — and where it isn’t — across sub‑Saharan Africa. It tells you which land uses are wrecking biodiversity, where most of the remaining wildlife actually lives (spoiler: it’s outside parks), and why one‑size‑fits‑all global maps may be steering bad policy. Handy for policymakers, NGOs, funders and anyone planning land or food systems interventions in the region.