The Living Planet Index (LPI) is a measure of the state of global biological diversity based on population trends of vertebrate species from around the world. The index represents 20,811 populations of 4,392 species. All indices are weighted by species richness, giving species-rich taxonomic groups in terrestrial, marine and freshwater systems more weight than groups with fewer species. Using a method developed by ZSL and WWF, these species population trends are aggregated to produce indices of the state of biodiversity.
The index value is measured relative to species’ populations in 1970 (i.e. 1970 = 1).Source: World Wildlife Fund (WWF) and Zoological Society of London