A global meta-analysis on patterns of amphibian and reptile diversity in agroforestry systems

Abstract

Global herpetofauna faces threats by habitat loss and degradation, with amphibian and reptile species maintenance in human-modified landscapes not only depending on forest remnants, but also on biodiversity-friendly matrices, such as agroforestry systems. Nevertheless, herpetological studies in agroforests are limited, hindering conservation decisions. To fill this gap, we conducted a global meta-analysis to assess the ability of agroforestry systems to maintain abundance and richness of amphibian and reptile species when compared to native forests. We analyze how community parameters (richness or abundance) and agroforest types based on the vegetation characteristics described by the studies (simplified or complex) impact the variation of overall effect size. We also used meta-regression models to examine how the amount of forest cover around agroforests affects the effect size. Finally, we calculated Sorensen's Index based on incidence data to investigate the degree of similarity in species composition of amphibians and reptiles between agroforestry systems and native forests. Our results showed that amphibian diversity in agroforests is lower than in native forests, regardless of the parameter and agroforestry type. For reptiles, agroforests showed higher abundance and similar species richness to forests. Simplified agroforestry systems support less reptile diversity than complex systems, which are more similar to forests. Interestingly, landscape forest amount modulates the ability of agroforests in maintain reptile richness. In fact, agroforests inserted in highly forested landscapes can harbor higher richness of reptiles than forests. We also found that half of the amphibian and reptile species observed in agroforests are different from those observed in native forests. Our findings highlights that agroforests cannot replace native forests because such systems harbor reduced abundance and species richness, especially amphibians, and a distinct species composition. However, when inserted in forested landscapes these agricultural systems can host rich reptile communities. Thus, preserving native forests and restoring deforested regions are crucial for herpetofauna conservation in human-modified landscapes.