Losing our palms: The influence of landscape-scale deforestation on Arecaceae diversity in the Atlantic forest

Understanding the effects of habitat loss on biodiversity has gained pronounced importance to inform conservation planning. Palms are a characteristic, important component of forest structure and the functionality of tropical forests, yet fragmentation-related studies have been poorly investigated in deforested landscapes. Here, we examine the influence of forest loss at the landscape scale on the entire palm community by evaluating species turnover at nine 16 km2 landscapes in the Brazilian Atlantic Forest with 9-71% forest cover. Additionally, we examine the influence of canopy openness at the local scale. We identified all live palms at the species level within 50 × 100 m forest plots at each site and classified species into categories based on their habitat occurrence (“forest-interior” and “open-area” species). The number of Arecaceae species and stems greatly declined with lower amounts of forest cover at the landscape scale, with the power-law model best explaining these relationships. The community composition was also affected by forest cover, in which higher species dissimilarity was observed among severely deforested landscapes. Additionally, our results showed that palm assemblages have been shaped by non-random processes, with forest-interior species being negatively affected by reduced forest cover at the landscape scale. Landscapes embedded within less than 40% forest cover harbored fewer than 10 palm species, mainly consisting of open-area forest species. Our study therefore demonstrates the pervasive influence of habitat loss on palm diversity in severely deforested landscapes in the Brazilian Atlantic Forest hotspot. Extensive management actions, including forest restoration and the reintroduction of animal dispersers, are urgent and serve as important tools to permit the successful recruitment, reproduction and establishment of palm species in the unique Atlantic Forest biome.