Background: Forested landscapes are valuable sources of ecosystem services especially in areas dedicated to intense agricultural activities. Distance from forest margin is known to influence the wild bee community in the landscape surrounding forested patches. Yet little is known regarding how bee communities distribute themselves in landscapes that exhibit different forest successional states. Methods: We examined how land use type and distance from the forest edge affect the abundance and richness of the wild bee community across four forest successional states. Bees were collected in sites representing four stages of forest succession and analyzed using generalized linear mixed models with negative binomial distributions. Results: Wild bee diversity is reduced in forested environments that maintain dense stands of trees and high canopy cover. Additionally, distance from the forest edge was an important factor determining wild bee distribution in successional stages adjacent to forest edges. Furthermore, we found that bees maintain high specificity for distinct successional states and distances. Conclusions: Our results demonstrate how different successional stages can harbor different bee species and highlight the ability of microhabitats to act as reservoirs of bee diversity in and around forest margins. Furthermore, we found that maximizing successional patchiness across forested landscapes increases the amount of available habitat that can support a diverse suite of bees with different nesting biologies and behaviors.

Longleaf pine savannas are highly threatened, fire-maintained ecosystems unique to the southeastern United States. Fire suppression and conversion to agriculture have strongly affected this ecosystem, altering overstory canopies, understory plant communities, and animal populations. Tree thinning to reinstate open canopies can benefit understory plant diversity, but effects on animal communities are less well understood. Moreover, agricultural land-use legacies can have long-lasting impacts on plant communities, but their effects on animal communities either alone or through interactions with restoration are unclear. Resolving these impacts is important due to the conservation potential of fire-suppressed and post-agricultural longleaf savannas. We evaluated how historical agricultural land use and canopy thinning affect the diversity and abundance of wild bees in longleaf pine savannas. We employed a replicated, large-scale factorial block experiment in South Carolina, where canopy thinning was applied to longleaf pine savannas that were either post-agricultural or remnant (no agricultural history). Bees were sampled using elevated bee bowls. In the second growing season after restoration, thinned plots supported a greater bee abundance and bee community richness. Additionally, restored plots had altered wild bee community composition when compared to unthinned plots, indicating that reduction of canopy cover by the thinning treatment best predicted wild bee diversity and composition. Conversely, we found little evidence for differences between sites with or without historical agricultural land use. Some abundant Lasioglossum species were the most sensitive to habitat changes. Our results highlight how restoration practices that reduce canopy cover in fire-suppressed savannas can have rapid benefits for wild bee communities.