Global metrics for terrestrial biodiversity

Biodiversity metrics are increasingly in demand for informing government, businesses, and civil society decisions. However, while there are many metrics available, it is not always clear to end-users how they differ or for what purpose they are best suited. This confusion undermines uptake. Here, we seek to clarify these questions by reviewing and presenting a database of 573 biodiversity-related metrics, indicators, indices and layers (hereafter ‘metrics’). Of these metrics, 227 are spatial data layers and 272 are temporal indicators. Assessed in relation to the pressure-state-response-benefits framework, 213 address only state, 118 address only pressures, 124 address only responses and 8 address only benefits. The remaining 110 relate to combinations of the four. Among the state indicators, 217 are bottom-up metrics (aggregated from individual components), 57 top-down (compiled through extrapolation), 8 are neither, and 1 is both; while 61 measure significance (‘biodiversity importance’) 86 intactness (‘biodiversity condition’), 5 both, and 131 are neither. These metrics address aspects of genetic diversity (19), species (106) and ecosystems (214), with 38 covering more than one aspect and 196 being general metrics. Considering complementarity across these characteristics, we recommend a small number of metrics considered most pertinent for use in decision-making by governments and businesses. We conclude by highlighting five future directions: increasing the importance of national metrics, ensuring wider uptake of business metrics, agreeing a minimum set of metrics for government and business use, automation of metric calculation through use of technology, and generating sustainable funding for metric production.