Factors affecting bee communities in forest openings and adjacent mature forest

Anthropogenic disturbance of habitat is considered a contributing factor of pollinator declines, but some disturbances such as silviculture, may have positive implications for pollinator communities. Silviculture is a key source of disturbance in the eastern USA and thus, developing a better understanding of its ramifications for these keystone species is important for effective ecosystem conservation. We sampled bees in 30 forest openings created by group selection harvest as well as 30 sites in adjacent mature forest to examine the extent to which small forest openings support bees, to identify environmental variables influencing bee abundance and diversity, and to gauge their potential to augment bee populations in adjacent unmanaged forest. Bees were significantly more abundant and diverse in forest openings than in mature forest, but species composition did not differ. There was no relationship between opening size and abundance or diversity of bees in openings or adjacent mature forest. Both abundance and diversity were generally positively related to the amount of early-successional habitat on the landscape. Within openings, overall abundance and diversity decreased with vegetation height and increased with a metric representing floral richness and abundance. Notably, social, soft-wood-nesting, and small bees exhibited the opposite pattern in adjacent forest, increasing with vegetation height in openings and decreasing with greater floral richness and abundance within openings. Our results suggest that the creation of small forest openings helps to promote bees both in openings and adjacent mature forest, but this pattern is not consistent for all guilds.