Depletion of biodiversity was defined as a decrease in species and habitat intactness, which affects the delivery of ecosystem services such as pollination and mass stabilisation, as well as recreation and tourism. 

The Biodiversity Intactness Index (BII), by Newbold et al. (2016), was determined to be a suitable indicator of depletion of biodiversity. The BII is a modelled average abundance of originally present species (species found in such an ecosystem in an intact state), relative to their abundance in an intact ecosystem (a pristine baseline). It models changes in the abundance and composition of ecological communities in response to a range of pressures, including land use change. It therefore reflects elements of habitat quantity and quality. The BII layer does not reflect recent change (unlike the other asset datasets used in the analysis) as intactness is modelled in comparison to fully intact natural habitat. A global layer depicting change in the BII (declines in the level of intactness compared to a fixed point in time) is in development, but not yet available. Eventually, this layer may distinguish areas where habitat loss is currently occurring from areas where habitat was lost historically. 

Large hotspots of biodiversity depletion (which correspond to the top 20% of relative depletion values) were found in the Great Plains in North America, the Southern cone of South America, Southern Africa, Central Asia, and Australia. The overlap of hotspots of biodiversity depletion with terrestrial biomes are detailed in Annex 2. 

Temperate Grasslands, Savannas and Shrublands had the greatest overlap (70%) with hotspots of depletion, whereas Boreal Forests and Taiga, and Tundra had close to no overlap.