Two for one: canopy gaps that improve the health of adelgid-infested eastern hemlock also favor bee diversity and abundance

Abstract

Creation of small canopy gaps around understory eastern hemlocks (Tsuga canadensis (L.) Carrière) can increase resilience to hemlock woolly adelgid (Adelges tsugae Annand), an invasive insect pest in eastern North America. In this study, the diversity and community composition of bees were quantified by monitoring pan traps in canopy gaps (mean size 0.06 ha, created 2.5—3 yrs earlier) and paired control plots (mature, intact forest) in western North Carolina and Virginia. Mean bee richness and abundance were significantly greater in silvicultural gaps. There were significant compositional differences in bee communities between treatments (gap vs. control) and forest locations (North Carolina vs. Virginia), and three indicator bee species were detected, all of which were associated with gaps. The mean health index of residual hemlocks at gap center was maintained over time, whereas the health index of hemlocks in control plots declined. These results suggest that in mature mixed hardwood – hemlock stands of the southern Appalachians, small-scale canopy disturbances can be used as a tool in the conservation of both eastern hemlock and native bee communities.

Citation

Mayfield, Albert E., III, Robert M. Jetton, Michael D. Ulyshen, Scott Horn, and Bryan T. Mudder. 2025. Two for one: canopy gaps that improve the health of adelgid-infested eastern hemlock also favor bee diversity and abundance. Journal of Forestry. https://doi.org/10.1007/s44392-025-00052-x