Data and analyses for: Localised patterns of wild bee abundance indicate woodlands play multiple roles in supporting farmland populations

Higher woodland cover has been linked to increased wild bee abundance and
diversity in temperate agricultural landscapes. However, our understanding
of the roles played by the upper and lower strata of woodlands in
supporting on-farm bees throughout the season is lacking. To explore these
roles, we sampled bees (Anthophila) in deciduous woodland canopies and
understories, and in an open habitat (at field margins), from May to July,
at 12 sites across agricultural landscapes in Norfolk, England. Before
canopy closure in late spring, relative abundance in the two woodland
habitats was generally higher, and canopies with flowering Acer
pseudoplatanus L. supported more bees. However, throughout the season,
open-habitat bee abundance was consistently higher closer to woodlands.
After canopy closure, more open areas within woodlands were linked to
greater bee abundance, except during a spike in temperatures when
understory relative abundance was also at its highest. These results
indicate that deciduous woods on farmland provide floral resources to bees
before canopy closure, which can be augmented with nectar-producing canopy
trees. They also indicate that more open woodlands likely extend the
availability of understory floral resources; and that farmland woods,
regardless of management, may continue to provide non-floral resources –
including respite from hot weather – throughout the season.