Effects of agricultural intensification on bee functional diversity in a coffee agroforestry system in Costa Rica: Can small noncultivated areas support functionally diverse bee communities?

Global declines among wild bee populations threaten ecosystem health and pollination services provided to agriculture. Only recently has the importance of wild bee pollinators for crop pollination been demonstrated empirically. Previous studies have shown that flowering crops grown in close proximity to noncultivated areas are visited by more species-rich bee assemblages, have more stable rates of bee visitation, and produce higher yields than those more distant from noncultivated areas. Proposed mechanisms underlying increased pollination stability and fruit set in these studies include enhanced response diversity, functional redundancy, and sampling effects within species-rich pollinator communities originating from noncultivated areas. However, agricultural intensification may reduce the ability for noncultivated areas to sustain diverse bee communities by reducing floral resources and nesting sites in the surrounding landscape. Moreover, the capacity for small noncultivated areas to sustain diverse wild bee populations in agricultural areas is largely unknown. Here we present ongoing research aimed at elucidating the effects of remnant natural area size and agricultural intensification on bee functional diversity in a coffee agroforestry system in Costa Rica. We sampled 19 forest patches (0.5 to 18 ha in size) that were surrounded by coffee farms characterized by an intensification gradient (intensive to moderately extensive) using a combination of pan traps and Blue Vane traps located in the understory and within the forest canopy.  We hypothesize that bee functional response diversity, and bee community stability will decrease with the size of noncultivated areas, but this effect will be pronounced in areas of highly-intensive farm management practices.