Thousands of Atlantic Forest Trees Face Extinction Risk

A comprehensive analysis of tree species' conservation statuses across Atlantic Forest trees reveals high extinction risks. According to the report, roughly two-thirds of the 4950 tree species living in this biodiversity hotspot are threatened with extinction. This includes 82% of endemic species, which have quite limited geographic ranges. Based on these findings, the authors suggest that the conservation status of tropical forests worldwide may be worse than previously believed. Conservation efforts and decisions often depend on assessments of species' conservation statuses. One such framework is the International Union for Conservation of Nature (IUCN) Red List, which categorizes species extinction risks based on a variety of criteria. However, Red List assessments require detailed data and considerable time and resources to produce on a species-by-species basis. As a result, comprehensive assessments of tropical biodiversity hotspots – where most threatened species occur – remain rare. Renato de Lima and colleagues developed an automated, quantitative method based on IUCN Red List categories and criteria to assess the conservation status of 4950 tree species from the Atlantic Forest in eastern South America – a relatively data-rich biodiversity hotspot compared to other tropical forest regions. Using data from herbarium records, tree counts from forest inventories, species life histories, commercial uses, and long time-series of habitat loss, de Lima et al. classified roughly 65% of all species and 82% of endemic species as threatened. Although five species previously classified as extinct on the Red List were rediscovered by the assessment, the authors identified 13 endemic trees that are now possibly extinct. Moreover, de Lima et al. used their results to project the conservation status of the 18 main tropical forests of the world. Based on the present forest cover of the world's tropical forests and the relationship between species threat and Atlantic Forest loss, the authors estimate that 20,504 to 24,910 tropical tree species – or 35 to 43% of tree species worldwide – are likely threatened with extinction due to habitat loss alone, suggesting that trees may be one of the most threatened groups of organisms on the planet.