Linking Landscape Features, Anthropogenic Stressors, and Mammal Abundance to Unveil Seed Removal Patterns in Tropical Deforested Landscapes

Abstract

Land-use changes and related anthropogenic pressures are responsible for biodiversity declines and threaten the provision of ecosystem services, especially in tropical forests. Seed dispersal and predation, for example, are especially important ecological processes for shaping plant diversity and composition; however, they can be strongly affected by such changes. Understanding factors that limit seed removal and, consequently, the final seed fate in human-modified landscapes is vital to enhancing our knowledge of ecosystem functioning. By using structural equation models, we evaluated the direct and indirect effects of landscape structure, anthropogenic stressors, and the abundance of terrestrial mammals on seed removal patterns of Eschweilera ovata (Lecythidaceae), a common large-seeded species, in 18 Atlantic Forest fragments in southern Bahia, Brazil. We used camera traps to record potential seed-removing mammals and spool line experiments to assess the ultimate fate of the seeds. We reveal a direct effect of patch size on the percentage of seeds removed, with seed removal decreasing in larger forest fragments. Our results also demonstrated a negative effect of human population density on mammal abundance; although a direct effect of mammals on seed removal was not detected. We, therefore, recommend that anthropogenic pressures should be mitigated to enhance the recovery of mammals in fragmented forest landscapes and that further research incorporate other potential predictors to better elucidate the complex patterns of seed removal in tropical forests.