The Atlantic Forest is one of the most threatened tropical forests in the world. Many species have declined and become isolated because of pervasive forest loss and degradation. Here we assess the current population status of Atlantic Forest tree species from Santa Catarina state in southern Brazil to inform conservation policies and future management and protection. We used a novel methodology to generate automated conservation assessments from forest surveys and herbaria data, based on IUCN criteria A, B, C and D. We assessed more than 500 tree species whose populations are considered threatened. Population size reduction (i.e. IUCN criterion A) was the main indicator of threat, followed by restricted geographical range (criterion B). We observed population reductions of over 50% over three generations in more than 60% of the assessments. We recommend including taxonomically verified herbaria data to improve the accuracy of conservation assessments. The results obtained here can be used to identify important and potential regions for creating protected areas and implementing forest restoration programmes.
