The multiple dimensions of biodiversity drive ecosystem function and the provisioning of ecosystem services. In insect pollinators specifically, species diversity is know to be important to ecosystem provisioning, but additional studies have shown that functional differences in species traits can be more important for ecosystem functioning than species identity. Therefore to more wholly understanding the impact of biodiversity and biodiversity loss on ecosystem functioning it is critical to incorporate multiple dimensions of biodiversity metrics.
In this study we ask how local and landscape factors of urban gardens correlate with bee diversity (species and functional) and then how the relationship between functional and species diversity varies between urban, agricultural and natural landscape habitats.
We sampled bees using both netting and pan trap methods once a month, from May-Sept 2015 across 18 different urban gardens surrounding Santa Cruz, California. We collected a total of 3164 individual bees representing 50 species. We identified eight important bee functional traits and then used linear mixed effect models with abundance-weighted species and functional diversity metrics to address our study questions.
Results/Conclusions
We found that both species and functional diversity of bees in urban gardens responded to similar local and landscape factors of (1) natural habitat, (2) floral resource availability and (3) ground cover. We further found that gardens surrounded by more natural landscapes had higher functional to species diversity relationship and gardens surrounded by more urban landscapes had lower functional to species diversity relationships. This suggests that bee communities in gardens from urban areas have lower functional redundancy and may be less resilient to future disturbance.