Local and landscape habitat influences on bee diversity in agricultural landscapes in Anolaima, Colombia

Abstract

Agricultural intensification drives biodiversity loss and is associated with bee declines. Bees are highly sensitive to environmental change, and while their diversity declines in simplified habitats distant from undisturbed areas, bees respond to agricultural practices and habitat configuration at different scales. Mountainous tropical agroecosystems are highly heterogeneous at local and landscape scales, and the responses of bee communities to environmental change in these regions are still underexplored. We examined the local and landscape habitat factors influencing bee abundance and diversity, and changes in bee generic and tribe composition in Anolaima, Colombia. We surveyed bees, measured local habitat features such as flower abundance, tree diversity, ground cover and vegetation structure, and evaluated land cover types and landscape characteristics in seventeen farms. We found that elevation, vertical structure of the vegetation and landscape structure influenced bee community structure. While local factors predicted the response of most individual bee groups, landscape factors influenced the abundance of Apis and Trigona, two genera with disproportionately high abundances across study sites. We also found that human constructions serve as refuges for several bee genera. Our paper suggests a process of biotic homogenization with the loss of bee diversity and concurrent spread of Apis and Trigona in landscapes dominated by pastures, unshaded crops or eroded soils. We also highlight the high sensitivity of native bees to habitat configuration and disturbance, and the importance of traditional farming systems for the conservation of bee communities in mountainous tropical agroecosystems.