Habitat degradation and destruction, particularly due to the expansion and intensification of agricultural systems, are the primary drivers of global biodiversity loss. Biodiversity decline has caused the reduction of many ecosystem functions and services in a variety of systems. Insect-mediated pollination is a critical ecosystem function and provides a tractable model for investigating impacts of landuse change on biodiversity and consequently, ecosystem functions. However, most studies to date have not considered functional trait diversity, which is a central component of biodiversity and a better predictor of ecosystem functioning than species diversity. Functional traits may determine both an organisms’ effect on ecosystem functions and its response to environmental change. Our paper reports on a landscape scale experiment, using targeted mass plantings along a landuse intensification gradient, to assess impacts on insect pollinator biodiversity and pollination services. We wanted to know: 1) at what rate does landuse intensification cause loss of pollinator trait redundancy; 2) do pollinator species have different responses to landuse intensification and 3) do pollinator species with redundant functional traits show parallel responses to landuse intensification? We planted floral resource plots at 12 sites that varied in the proportion of agricultural land within a 2000m radius. We measured pollinator visitation rates, single visit pollen deposition and collected voucher specimens at each site. Functional traits of pollinator species were also measured.
Results/Conclusions
We show that landuse intensification has caused substantial loss of pollinator functional diversity and that functional redundancy (number of species occupying the same functional niche) decays rapidly with intensification. However, we find that responses to intensification are species specific, with some species responding positively to intensification while others have negative or neutral responses (i.e. there is strong response diversity). The extent to which species with similar functional traits (i.e. redundant) show different or similar responses to landuse change is critical for predicting the magnitude of the impact that landuse change has on ecosystem functions such as pollination.