Wild bees are active in woodland tree-tops

The shaded interiors of woodlands have generally been considered a poor habitat for sun-loving wild bees. However, according to a new study led by the University of East Anglia (UEA), bees may be just as happy visiting the high, sunlit canopy of woodlands as they are among the flowers at ground level. Thus, woodland canopies may play a more significant role in bee conservation efforts than previously thought, particularly with nectar- and pollen-rich Sycamore trees proving attractive to these major pollinators.

“Wild bees are a major contributor to crop pollination services, but to thrive in agricultural landscapes they also need non-crop habitats to provide places to nest and flowers to feed on,” said study senior author Richard Davies, a biologist at UEA. “Shaded woodland interiors are often considered poor foraging habitat for bees, but until now, bee activity in the sunlit woodland canopy has scarcely been investigated.”

The researchers investigated bee communities across 15 woodland areas in a farmed landscape in Norfolk in late spring in order to better understand the levels of bee activity in various habitats, including the canopy (at heights of up to 20 meters), and the understory of both woodland interiors and exposed woodland edges. 

“We found that a diverse community of wild bees are active in the woodland canopy – by which we mean high up among the trees’ branches and foliage. Activity levels were particularly high near flowering Sycamore trees,” reported study lead author Guthrie Allen, an expert in Ecology at UEA.

“We also found that bee communities differ between the woodland canopy and understory – the layer of vegetation growing close to the woodland floor. And we were surprised to find that most bee species were just as abundant in the understories of woodland interiors as they were at the sun-exposed edges bordering farmland.”

These findings suggest that wild bees have a great potential to exploit the rich sources of nectar and pollen available in woodland canopies. While nectar-producing trees, such as Sycamores, represent a significant food source for a diversity of bee species, some bees may even collect pollen from wind-pollinated trees like oaks.

“Further investigation is needed to understand why communities differ between the canopy and understory, but overall, our work suggests that woodlands play a more significant role in supporting farmland bee communities than previously thought,” Allen concluded.

The study is published in the journal Insect Conservation and Diversity.

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By Andrei Ionescu, Earth.com Staff Writer