Functional group diversity of bee pollinators increases crop yield

摘要

Niche complementarity is a commonly invoked mechanism underlying the positive relationship betweenbiodiversity and ecosystem functioning, but little empirical evidence exists for complementarity amongpollinator species. This study related differences in three functional traits of pollinating bees (flower heightpreference, daily time of flower visitation and within-flower behaviour) to the seed set of the obligate cross-pollinated pumpkin Cucurbita moschata Duch. ex Poir. across a land-use intensity gradient from tropicalrainforest and agroforests to grassland in Indonesia. Bee richness and abundance changed with habitatvariables and we used this natural variation to test whether complementary resource use by the diversepollinator community enhanced final yield. We found that pollinator diversity, but not abundance, waspositively related to seed set of pumpkins. Bees showed species-specific spatial and temporal variation inflower visitation traits and within-flower behaviour, allowing for classification into functional guilds.Diversity of functional groups explained even more of the variance in seed set (r2=45%) than did speciesrichness (r2=32%) highlighting the role of functional complementarity. Even though we do not provideexperimental, but rather correlative evidence, we can link spatial and temporal complementarity in highlydiverse pollinator communities to pollination success in the field, leading to enhanced crop yield withoutany managed honeybees.