Biodiversity intactness score for South Africa

Abstract

South Africa's new Biodiversity Act requires the development of a national framework for the integrated management of biodiversity in the country. The act also requires regular monitoring and reporting of the status of biodiversity. We apply a new approach, the Biodiversity Intactness Index (BII), to assess the state of biodiversity in South Africa. The index is a measure of the change in abundance across all well-known elements of biodiversity, relative to their inferred pre-colonial state. The BII can be calculated nationally, by province, municipality, or ecosystem type, or any other defined spatial unit. We estimate that, averaged across plants, mammals, birds, reptiles and frogs, abundances have declined by 19 ±7% over the past three centuries in South Africa. Losses are greatest in the grassland, fynbos and forest biomes, and mammals are the most affected taxonomic group. It is estimated that 80% of the remaining wild organisms in South Africa are in the extensive areas predominantly under grazing management. This suggests that the policy action with the greatest potential to limit further loss of biodiversity is to prevent the degradation of these areas, which could potentially halve the abundance of the remaining wild organisms.