Assessing the potential role of different land covers for conserving threatened amphibian diversity in a human-modified tropical mountain landscape

Abstract

We evaluated the potential role of old-growth forests (>100 years), secondary forests of two different ages (35–40 years and 15–20 years, respectively), shaded coffee polycultures, and cattle pastures for conserving amphibian diversity, particularly threatened species, in a human-modified landscape originally covered by cloud forest. In 2017, we sampled 9000 m² of each of these five habitats and recorded a total of 681 amphibians belonging to 14 species, six of which were threatened. When all species were considered, there were no significant differences in species richness between studied land covers. However, considering only threatened species revealed a monotonic decrease in species number from old-growth forests (where all threatened species were recorded) to cattle pastures (where only one threatened species was observed). Additionally, the most threatened species (critically endangered and endangered) were only recorded in old-growth forest and older secondary forest. Assemblage structure and species composition of threatened species were most similar between the two types of secondary forests, followed by the old-growth forest. Tree density, herbaceous cover, and leaf-litter depth were the variables best explaining observed patterns of overall amphibian diversity. These findings suggest that the protection of old-growth forest fragments is essential for conserving threatened amphibian species, especially salamanders, in highly modified landscapes, and that conserving or promoting secondary forests could also facilitate the recovery of this threatened biota. Shade coffee plantations seem to have a very limited role for threatened amphibian species, while cattle pastures play no role in conserving these species.