UC Davis

This research contributes to solving current bee habitat shortcomings affecting native and naturalized bees in California and identifies strategic habitat best management practices for novel ecosystems. Habitat loss and fragmentation are major causes of decline in bee populations today. Targeted, strategic habitat analysis and modifications could help to boost both habitat connectivity and habitat for bees. First, this research takes a novel approach to habitat analysis by building bee-to-plant habitat relationships foraging models. A presence-only bee-to-plant foraging matrix was compiled from existing literature and contains 23 bee genera and 134 plant genera. This bee foraging matrix was field-tested, and validated to assess its accuracy by weekly observations in 35 gardens at the UC Davis Arboretum and Public Garden over one calendar year. Findings suggest existing ‘pollinator friendly’ plant lists for California bees have significant shortcomings in predicting foraging associations. These results suggest that for the vast majority of bees in California, the existing literature reflects little of their foraging associations. Novel associations demonstrating high foraging frequencies and attracting many bee genera should be considered for improving designed bee habitats. Next, this research uses geographic information systems (GIS) to spatially measure the geographic distances between pollinator foraging plants throughout one year. Assessments of the expected (potential) habitats and observed (utilized) foraging associations further test the ability of recommended plant lists in their ability to attract and sustain bee genera. Examining these results spatially helps to shed light onto how bee habitat fragmentation occurs over a landscape. GIS mapping technology helps to show geographically how bee foraging trends are spatially and temporally distributed, giving further insight into how pollinator habitat networks function and where gaps occur. Comparison between the 35 themed gardens allowed assessment of their value as ecosystems and to gauge the level of pollination ecosystem services they provide. Additionally, due to the linear layout of the Arboretum it is possible to test habitat fragmentation among individual bee genera and the gardens. Since bees vary greatly in their foraging range abilities, those differences in range were accounted for in the mapping model. Spatial habitat analysis is done to compare potential versus actual bee feeding trends and how bee feeding habitat utilization works in a landscape system. Furthermore, the characteristics which make each garden successful as habitat or not are examined. By examining the Arboretum thoroughly from bees’ perspectives, it is possible to identify ecological shortcomings of the Anthroscape and design ecologically strategic and precise habitat solutions to habitat fragmentation. This research aims to boost habitat connectivity and bee population persistence, in doing so, protecting pollination networks and services.