Riparian Amphibian and Reptile Assemblages in Streams Along a Forest Regeneration Gradient in the Ecuadorian Chocó

Abstract

While primary forests are declining, regenerating habitats are becoming increasingly common. In fragmented environments, streams may function as corridors between forest remnants for riparian and aquatic species. However, the responses of stream-associated species to forest regeneration remain understudied. In this study, we compared the abundance, diversity, and species composition of stream-obligate amphibians and reptiles along 17 stream sites, surrounded by habitats at different forest regeneration stages. These sites included actively used cacao plantations and pasture, forest regenerating from former cacao and pasture land, and old-growth forest. We collected environmental data and conducted time-standardized visual and auditory surveys along stream transects. Diversity indices and multivariate community analyses were used to assess the influence of habitat variables on assemblage composition. Streams in regenerating forests supported higher herpetological richness and diversity than primary forests, whereas actively used sites had the lowest diversity; however, these differences were not significant. Amphibian diversity was higher in pasture regeneration streams than in actively used pastures, whereas reptiles showed no significant differences. Canopy and understory vegetation densities were the strongest predictor for stream amphibian assemblage differences, whereas broader environmental conditions and correlated climate and structural variables shaped stream reptile distributions. Amphibians showed more pronounced species shifts between regeneration states, demonstrating higher sensitivity to disturbance than reptiles. Our findings highlight the importance of riparian vegetation and water availability in both active and regenerating sites for sustaining stream herpetofaunal diversity in tropical landscapes.