The bii4africa dataset of faunal and floral population intactness estimates across Africa's major land uses

Abstract

Sub-Saharan Africa is under-represented in global biodiversity datasets, particularly regarding the impact of land use on species' population abundances. Drawing on recent advances in expert elicitation to ensure data consistency, 200 experts were convened using a modified-Delphi process to estimate 'intactness scores': the remaining proportion of an 'intact' reference population of a species group in a particular land use, on a scale from 0 (no remaining individuals) to 1 (same abundance as the reference) and, in rare cases, to 2 (populations that thrive in human-modified landscapes). The resulting bii4africa dataset contains intactness scores representing terrestrial vertebrates (tetrapods: ±5,400 amphibians, reptiles, birds, mammals) and vascular plants (±45,000 forbs, graminoids, trees, shrubs) in sub-Saharan Africa across the region's major land uses (urban, cropland, rangeland, plantation, protected, etc.) and intensities (e.g., large-scale vs smallholder cropland). This dataset was co-produced as part of the Biodiversity Intactness Index for Africa Project. Additional uses include assessing ecosystem condition; rectifying geographic/taxonomic biases in global biodiversity indicators and maps; and informing the Red List of Ecosystems.

Fig. 1

Overview of the structured expert elicitation process, based on the IDEA protocol (Investigate, Discuss, Estimate, Aggregate). This process was run for each broad taxonomic group (Table 1), between November 2020 and January 2022, to elicit from 200 experts the estimated impact of nine major African land uses (Table 2) on the relative population abundances of terrestrial vertebrates and vascular plants.

Fig. 2

Attributes of the 200 participating experts. All values in white font (and black font on the cord plot) represent the number of experts. Numbers do not add up to 200 when categories are not mutually exclusive (region, taxonomic group, employment sector) or when experts did not report a certain attribute (unk = unknown; Mamm = Mammals; org. = organisation).

Fig. 3

Intactness scores depicting the remaining proportions of ‘intact’ reference populations of terrestrial vertebrates (tetrapods) in different land uses, where 0 indicates that no individuals remain and 1 indicates the same number of individuals as in an ‘intact’ reference population. Average scores across experts (±95% confidence intervals; CI) are shown. The left panel (a) depicts an aggregated score for each taxonomic group and land use – an average across species response groups, weighted by species richness (i.e., response groups representing a higher number of species in a taxonomic group count more towards its aggregated score). The right panels show examples of the scores for species response groups in two taxonomic groups in different land uses: (b) reptiles in non-intensive, smallholder croplands and (c) bats in intensive rangelands.

Fig. 4

Intactness scores depicting the remaining proportions of ‘intact’ reference populations of terrestrial vascular plants in different land uses, where 0 indicates that no individuals remain and 1 indicates the same number of individuals as in an ‘intact’ reference population. Average scores across experts (±95% confidence intervals; CI) are shown. The left panel (a) depicts an aggregated score for plants in each land use in each biome – an average across species response groups, weighted by species richness (i.e., response groups representing a higher number of species in a biome count more towards its aggregated score). The right panel (b) shows an example: the scores for plant species response groups in intensive rangelands in the mixed-acacia savanna biome. (Thicket and fynbos biomes are not shown because of low sample sizes: <3 expert scores across all land uses; USO = underground storage organ).

Fig. 5

Change in the variation (standard error) of estimated intactness scores for each species response group and land use, between the first and second round of the expert elicitation process. Boxplots show median (horizontal line in the box), interquartile range (box), and max/min values within 1.5 times the interquartile range (vertical lines). Values less than 0 (below the red-dashed horizontal line) show a decrease in score variability between experts. For terrestrial vertebrates, results are shown per taxonomic group; for terrestrial vascular plants they are shown per biome. (C-m = Caesalpinioid-miombo; Mamm = Mammals).