Biodiversity and community composition of native bee populations vary among human-dominated land uses within the seasonally dry tropics

Abstract

Human-dominated land uses constitute a large and growing proportion of global land cover, so understanding their potential to support biodiversity is critical for effective conservation. Here, we asked how bee diversity and community composition differ among common human dominated land uses (teak plantations, coffee agroforestry, and pastures) during wet and dry seasons in the Nicoya Peninsula of Costa Rica. We sampled over two years using blue vane and pan traps, collecting 47 genera and 119 species and morphospecies of bees. We observed similar numbers of bees in coffee farms and high elevation pastures, but collected substantially more bees in low elevation pastures relative to teak plantations during both seasons. Shannon diversity was greatest in pastures, with an estimated 20 more common species in low elevation pastures relative to teak plantations and estimated 13 more common species in high elevation pastures relative to coffee. Teak plantations were dominated by distinct taxa during the dry season compared to the other land uses, hosting stem-nesting genera such as Ceratina but lacking oil collecting groups like Centris and Epicharis. Our findings reflect the seasonal availability of habitat: teak is managed as a monoculture and blooms during the wet season, when fewer bees are active. In contrast, shade trees in pastures provide nectar, pollen, and nesting substrates throughout the year. Our study provides baseline information on regional bee biodiversity in a tropical agroecosystem, demonstrating the influence of both season and land use on an important group of pollinators in this system. To avoid biodiversity trade-offs, policies that incentivize the establishment of teak plantations as a form of reforestation should incorporate land management that enhances habitat of important insects such as native bees.