A composite measure of habitat loss for entire assemblages of species

Abstract: "Habitat destruction is among the greatest threats facing biodiversity, affecting common and threatened species alike. However, metrics for communicating its impacts typically overlook the non‐threatened component of assemblages. This risks the loss of habitat for species that comprise the majority of assemblages going unreported. Here, we adapt a widely‐used measure for summarizing researcher output (the h index) to provide the first metric describing natural habitat loss for entire assemblages, inclusive of threatened and non‐threatened species. For each of 447 Australian native terrestrial bird species, information on their association with broad vegetation groups was combined with distributional range maps to identify the difference between the estimated pre‐European and current extents of potential habitat. From this, we calculated the ‘Loss Index’ (LI), which reveals that 30% of native birds have each lost at least 30% of their potential natural habitat—an LI of 30. At the sub‐continental scale, the LI ranges from 15 in arid Australia to 61 in the highly transformed south‐east of the country. Further, different subcomponents of the assemblage have different LI values; for example, Australia's parrots ( n=52 species) have an LI of 38, while raptors ( n=32 species) have an LI of 25. The LI is simple to calculate, and can be determined using readily available spatial information on species distributions, habitat associations and human impacts on natural land cover. This metric, including the curves that are used to deduce it, could complement other biodiversity indices by being used for regional and global biodiversity assessments, comparing the status of natural habitat extent for assemblages within and among nations, monitoring changes through time, and forecasting future changes to guide strategic land use planning. The LI is an intuitive tool with which to summarise and communicate how human actions affect whole assemblages, and not just those that species identified as threatened."

Read More: https://onlinelibrary.wiley.com/doi/abs/10.1111/cobi.13331