Flower strips can boost wild bee populations

In intensive agriculture landscapes, wild bees are rare due to the low availability of flowers as nectar and pollen sources, leading to significant problems for crop systems such as apple orchards, which are dependent on pollination. However, a new study led by the University of Freiburg in Germany has found that using a combination of hedges and perennial flower strips could support wild bee diversity and abundance in orchards by providing continuous resources during the entire growing season. 

Between 2018 and 2020, the researchers compared flower resources and wild bee populations across 18 apple orchards in the Lake Constance area of Germany, one of the country’s leading apple growing regions. The analysis revealed that orchards housing a combination of hedgerows and perennial flower strips had a larger and more diverse population of bee pollinators. Wild bee species were found to visit flowering hedges from March to June, and perennial flower strips from June to August in the first year of planting, and from April onwards in subsequent years.

“For enhancing wild bees in intensive agricultural landscapes one should provide a network of perennial flower strips and some well-maintained hedges to create a continuous flower offer over the entire growing season,” said study lead author Vivien von Königslöw, an expert in Nature Conservation and Landscape Ecology at Freiburg.

“Our results suggest preferential establishment of perennial flower strips rather than annual flower strips because perennial flower strips flower much earlier in the second year of establishment than in the year of sowing and attract different bee communities over the years. Thus, they are more suitable to enhance bee diversity,” she added. 

Although hedges and perennial flower strips were found to complement each other, the scientists nevertheless argued that the latter are benefitting wild bees the most, since they are in bloom during periods when other flowers are scarce, while hedges predominantly overlap with apple trees and orchard ground vegetation flowering in spring.

The study is published in the Journal of Applied Ecology. 

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By Andrei Ionescu, Earth.com Staff Writer