Commonness as a reliable surrogacy strategy for the conservation planning of rare tree species in the subtropical Atlantic Forest

Global biodiversity is declining at rates never seen before. At the same time, resources directed at conservation planning still fall orders of magnitude short. Thus, efficient allocation of resources is needed to prioritize regions that can shelter more biodiversity. A usual approach to identify priority areas for conservation is to map species distribution and use this information as input in spatial prioritization proceedings. Since data on common species are more readily available, final maps of priority areas for conservation are heavily biased towards this group, overlooking rare species. Thus, we created a ranking of priority maps for common and rare tree species, separately, aiming to comprehend if prioritizing areas for the conservation of common trees is enough to protect rare trees all at once. Additionally, we overlapped our priority maps with maps of current protected areas (PAs) to identify if the latter already cover areas designated in our models. Our results show that common tree species can act as surrogates for rare tree species since priority maps for both groups overlap with more than 70% of their area. Yet, most of the current PAs do not cover significant areas for protecting tree species, revealing an urgent need to expand or create new PAs to properly safeguard the local biodiversity.