Bees are keystone organisms that fundamentally contribute to pollination of both wild plants and food crops worldwide. Due to the recent decline of domesticated honeybees, farmers may increasingly rely on native bees for pollination services. Therefore, it is important to maintain an abundant and diverse native bee community not only for the vital ecological role they play, but also for their instrumental value in agroecosystems. This study investigated the impacts of varying land-use practices on native bee abundance and diversity. Two collection methods, pan traps and sweep netting, were used to monitor native bee abundance and diversity at six study sites in Southeastern Massachusetts from April-October 2016 and April-July 2017. Study sites varied regarding the use of sustainable landscaping practices such as no-mow zones, native landscaping, and reduced chemical use, as well as in degree of urbanization. The six sites were designated as urban or rural based on GIS-analysis of percent impervious surface area within a 300-meter buffer zone.
Results/Conclusions
Three of the study sites were designated as urban based on relatively high impervious ground cover (>30%). Two of these sites are located on a college campus where sustainable landscaping practices are employed. Sites designated as rural had relatively low impervious ground cover (<8%) with one site located on the property of a commercial farm. Native bee diversity (Shannon index) was significantly different among sites but did not exhibit significant change from 2016 to 2017. The two sites on the urban college campus showed significantly higher Shannon indices and abundances (based on pan trap data) compared to the other urban site, and similar diversity and abundance to the three rural sites (a priori contrasts). Sweep net abundance data also differed among sites, but not years, and pairwise comparisons revealed only one urban site (without sustainable landscaping) had significantly lower abundance than one of the rural sites. The rural site with the highest abundance did not have the highest diversity. This is indicative that different land-use practices may have independent effects on abundance and diversity. Our results suggest that rural areas may generally provide better habitat for native bees, but better land management practices may increase abundance and diversity even in urban settings.