Woody debris provides habitat for a wide range of wildlife, including many wild bees that nest in cavities in dead wood. However, few studies have assessed the value of woody debris for wild bees, or how its management may impact bee communities. In this study, we investigated the relationships between woody debris availability and bee community dynamics across 23 different sites along the St. Vrain River in Colorado’s Front Range. Between May and September 2016, we sampled each site 6 times using hand-netting to collect bees, and line-intercept methods to sample woody debris. We then explored the relationship between woody debris and bee communities using generalized linear modeling.
Results/Conclusions
We netted a total of 3,662 bees (x̅ = 159.2 ± 17.7 bees per site) across 5 families (Andrenidae, Apidae, Colletidae, Halictidae, and Megachilidae) and 32 different genera (x̅ = 15.7 ± 0.7 genera per site). 12 of these genera were dominated by cavity-nesting species (x̅ = 6.0 ± 0.4 genera per site) totaling 819 cavity-nesting bees across sites (x̅ = 35.6 ± 6.1 per site). We found significant positive relationships between the volume of woody debris at each site and both total bee abundance (z=12.17, p<0.001) and cavity-nesting bee abundance (z=5.1, p<0.001), indicating that woody debris is beneficial to bee communities and likely provides valuable habitat for cavity-nesting species. These conclusions suggest that wild bee conservation should be an important consideration in woody debris management.