Studies show that wild bees are active in tree tops

According to new research from the University of East Anglia, wild bees may be just as happy visiting the high canopies of forests as they are among flowers at ground level.

Shaded woodlands are generally considered poor habitat for sun-loving bees.

But a new study published in the Conservation and diversity of insects today shows that a diverse community wild bees active high above the shade – among tree branches and foliage in the sunlit forest canopy.

The team argues that forest canopies may play a more significant role in bee conservation than previously thought, with nectar- and pollen-rich sycamore trees proving particularly attractive to bees.

Dr Richard Davies, from UEA’s School of Biological Sciences, said: “Wild bees make a huge contribution to crop pollination services, but to thrive in agricultural landscapes they also need non-crop habitats to provide nesting sites and flowers for nourishment. Shaded forests are often considered poor foraging environments for bees, but until now, bee activity in sunlit forest canopies has barely been studied.”

Lead researcher Guthrie Allen, also from UEA’s School of Biological Sciences, said: “We wanted to learn more about the potential of forest canopies to support wild bee communities.”

In late spring, the team surveyed bee communities in 15 woodland sites in an agricultural landscape in Norfolk. They studied the level of activity of bees in four habitats – in the canopy (at a height of up to 20 meters) and in the understory of both inner forests and open forest edges.

Allen said: “We found that a diverse community of wild bees is active in the forest canopy – by which we mean high up in the tree branches and foliage. Activity levels were particularly high near flowering sycamore trees. We also found that bee communities differ between the forest canopy and the understory, the layer of vegetation that grows close to the forest floor.

“And we were surprised to find that most bee species were as abundant in the understory of interior forests as they were in the sun-exposed edges bordering agricultural land. Our results show that wild bees can use abundant sources of nectar and pollen available in forest canopies. Nectar-producing trees such as the sycamore are likely to be an important food source for many bee species, while some may even collect pollen from wind-pollinated trees such as the oak.

“Our findings also show that the understory of managed forests can support bee communities. Further research is needed to understand why communities differ between canopy and understory, but overall our work suggests that forests play a more significant role in supporting agricultural bee communities than previously thought,” he concluded.

Additional information:
“Canopy sampling reveals hidden potential value of forest trees for wild bee collections”, Conservation and diversity of insects (2022).