Land-use heterogeneity by small-scale agriculture promotes amphibian diversity in montane agroforestry systems of northeast Colombia

Abstract

Habitat fragmentation, the transformation of interconnected large habitats into several small patches, is generally considered to have a negative influence on biodiversity. Management policies should therefore favour strategies that minimize fragmentation. We studied amphibian diversity and compositional patterns in a complex montane agroforestry matrix of north-eastern Colombia to assess whether small-scale agroforestry is a viable way of reconciling crop production, farming, and biodiversity conservation. A total of five different land-use systems, including natural cloud forest, were compared. We used standardized visual and acoustic transect sampling routines in combination with field-based habitat assessments to establish amphibian assemblage data sets and corresponding habitat templets. Data sets were analysed using classical species richness and diversity statistics in combination with multivariate procedures to address compositional aspects. PER(mutational)MANOVA models were applied to identify environmental and land-use type-specific drivers of shifts in assemblage composition. Results show that agricultural management has a strong influence on amphibian species richness and diversity. With the exception of high intensity cattle pasture, diversity was generally highest in agriculturally used sites particularly in shaded plantations. Species composition differed markedly between different land-use types, indicating that there was not a single best land-use type that supported all species. This highlights the need for a landscape approach to biodiversity conservation in fragmented forests and consequently requires refocusing on conservation in management units as well as in the matrix. In human modified montane forest landscapes small-scale agriculture that generates landscape heterogeneity should therefore be promoted to effectively safeguard biodiversity.