Forest and trees: Shade management, forest proximity and pollinator communities in southern Costa Rica coffee agriculture

Sustained pollinator services within coffee farms depend substantially on a diverse bee community. While studies have been conducted to understand the impacts of forest proximity and farm level management on pollinators, few have examined the interaction between these two spatial scales. We surveyed pollinator communities within 18 sites on a large organic farm surrounded by native forest in southern Costa Rica. We selected sites 0, 50 and 150 m from the forest edge within shaded and sparsely-shaded (sun) portions of the farm to quantify the influence of both shade management and distance to contiguous forest on pollinator communities. Contrary to similar studies, native bees dominated the composition of pollinators on this farm. Overall, pollinator diversity and activity did not differ significantly neither between the shade management types nor among the sites 0, 50 or 150 m from the forest edge. However, pollinator diversity was found to be significantly higher at sun sites near forest (0 m) compared with further away, whereas the diversity was the same for the shade sites regardless of forest proximity. We found that greater numbers of coffee flowers within each site increased bee abundance and flower visitation frequency. Bee abundance was greater in sites with less ground cover and bee diversity and visitation frequencies were higher in sites with greater amounts of shade canopy cover and trees in flower. Based on our results, we suggest including flowering shade trees that provide high levels of canopy cover, maintaining or re-establishing forested areas within or surrounding farms, and eliminating or reducing agrochemical use to increase native pollinator activity and diversity within coffee farms.