Urban expansion and its impact on species ranges and Key Biodiversity Areas in Indonesia

Indonesia has experienced rapid urban growth over the last few decades with significant implications for the country's biodiversity. In this study, we asked how animal species ranges in Indonesia have been affected by urban land expansion from 1992 to 2020, and if Key Biodiversity Areas (KBAs) that overlap with designated protected areas had experienced less urban land expansion than those that do not. Our results show that urban land increased by around 76% across the country and 81% within its KBAs during this period. Throughout our study period, both the number of species with any urban land within their ranges and the urban land within these species ranges increased. Among the four taxa, birds have the greatest number of species with ranges containing at least 2% urban land. Notably, the number of mammalian species with high urban land within their ranges (≥20% of their range) increased sixfold by 2020, a trend observed across both threatened and non-threatened categories. There was not a statistically significant difference in urban land expansion between protected and unprotected KBAs. We also found that the number of KBAs encroached by urban land increased by over 9% overall, with a higher percentage of protected KBAs (55%) being impacted than unprotected ones (32%) in 2020. Our findings highlight the need for including conservation-focused urban management strategies at the national level for effective safeguarding of biodiversity from urban expansion and imply the inadequacy of existing measures at KBAs that are under formal protection.