Diverse forest management strategies support functionally and temporally distinct bee communities.
Abstract
Forests worldwide support insect biodiversity and the ecosystem services provided by insects such as pollination. As forest health declines, management that emulates historical disturbance regimes has the potential to restore and maintain forest ecosystem functioning; however, we lack understanding of how these practices affect key mutualists like bees and the ecosystem services they provide. To fill this knowledge gap, we investigated the functional response of bee communities to temperate deciduous forest management practices that emulate historical disturbances (burning, thinning and the combination of the two). We also investigated whether seasonality has any effect on this relationship. Bee functional diversity was highest in spring compared to summer, and management did not affect this relationship. Instead, different management strategies aligned with specific bee functional traits and these relationships varied throughout the year. Managed and unmanaged areas differed in the distribution of nesting and floral resources and, as a result, altered bee functional trait composition. Thinned plots with increased floral resources promoted smaller bees with limited dispersal capacity, in addition to primitively eusocial and cavity-excavating bees. Unmanaged habitat supported vulnerable bee groups such as cleptoparasites and specialists. Burning by itself or in combination within thinning may have eliminated crucial nesting resources such as deadwood that bees depend on in forests. Synthesis and applications: Our findings demonstrate that managing temperate forests by emulating historical disturbances can support a functionally diverse bee community and highlight the need to consider temporal variation in the environmental drivers of forest bee communities. To support year-round bee diversity, forest management strategies should prioritize floral resources and leave behind deadwood to increase bee nesting resources, as well as maintain unmanaged habitat within the forest landscape. Overall, our study reinforces the importance of using a range of forest management strategies to enhance bee functional diversity and associated ecosystem services.