Data from: Habitat restoration benefits wild bees: a meta-analysis

1.Pollinator conservation is of increasing interest in light of managed
honeybee (Apis mellifera) declines, and declines in some species of wild
bees. Much work has gone into understanding the effects of habitat
enhancements in agricultural systems on wild bee abundance, richness, and
pollination services. However, the effects of ecological restoration
targeting “natural” ecological endpoints (e.g., restoring former
agricultural fields to historic vegetation types or improving degraded
natural lands) on wild bees have received relatively little attention,
despite their potential importance for countering habitat loss. 2.We
conducted a meta-analysis to evaluate the effects of ecological
restoration on wild bee abundance and richness, focusing on unmanaged bee
communities in lands restored and managed to increase habitat availability
and quality. Specifically, we assessed bee abundance and/or richness
across studies comparing restored vs. unrestored treatments and studies
investigating effects of specific habitat restoration techniques, such as
burning, grazing, invasive plant removal and seeding. 3.We analysed 28
studies that met our selection criteria: these represented 11 habitat
types and 7 restoration techniques. Nearly all restorations associated
with these studies were performed without explicit consideration of
habitat needs for bees or other pollinators. The majority of restorations
targeted plant community goals, which could potentially have ancillary
benefits for bees. 4.Restoration had overall positive effects on wild bee
abundance and richness across multiple habitat types. Specific restoration
actions, tested independently, also tended to have positive effects on
wild bee richness and abundance. 5.Synthesis and applications. We found
strong evidence that ecological restoration advances wild bee
conservation. This is important given that habitat loss is recognized as a
leading factor in pollinator decline. Pollinator responses to land
management are rarely evaluated in non-agricultural settings and so
support for wild bees may be an underappreciated benefit of botanically
focused management. Future restoration projects that explicitly consider
the needs of wild bees could be more effective at providing nesting,
foraging and other habitat resources. We encourage land managers to design
and evaluate restoration projects with the habitat needs of wild bee
species in mind.