Flowers and Hedges Team Up to Help Bees

Perennial flowers and hedges work together to provide continuous resources to support wild bees, a new study finds.

Researchers in Germany studied wild bee populations surrounding orchards, which depend on pollinators. They found that the flowering cycles of hedgerows and strips of perennial flowers complement each other, leading to greater wild bee diversity and abundance.

“Our impetus was to find ways to increase biodiversity in intensive agrosystems while keeping high yields—as we assumed that this makes acceptance among farmers much higher,” lead author Vivien von Königslöw of the University of Freiburg in Germany, tells Treehugger.

“Apple orchards seemed optimal study systems in this regard because pollination, which is crucial for high yields, is linked to (pollinator) biodiversity. Thus farmers might have a special interest in such biodiversity measures.”

For their study, researchers focused on areas on the edges of 18 privately owned apple orchards in southern Germany. For some areas, they established perennial flower strips or added a layer of herbs to existing hedges. Other areas they left alone with existing hedges or no enhancements at all.

They compared the activity and growth of the bees and flowers over a three-year period. They found that bees visited the hedges primarily from March to June and spent time at the flowers from June to August that first year. By the second year, they visited the flowers starting in April.

The flowers attracted more bees overall and more bees of various species compared to the hedges or improved hedges alone.

“Perennial flower strips and hedges complement each other in providing flowers at different time periods. A combination of both covers basically the whole vegetation season,” says von Königslöw.

“Landscapes with both perennial flower strips and hedges thus provide food resources for basically the whole bee community, may it be social wild bees like bumblebees (which are active from spring to fall) or solitary bees (which have species-specific flight periods, in total also covering the entire vegetation season).”

In addition, the orchards offer the majority of flowers in spring with apple blooms. But after the peak bloom, the orchards only provide a few flowers with not much diversity.

The results were published in the Journal of Applied Ecology.

From Orchards to Backyards

The perennial mix in the study included species such as viper's bugloss and mallow. Researchers say it’s key to use perennials over flowers that bloom only annually.

Perennials begin flowering much earlier, starting in their second year after planting, which means they provide flowers much earlier in the season.

“Furthermore they attract overall different species assemblages in the different years, amongst others because different plant species come to flower in the different years,” von Königslöw says. “In landscapes with perennial flower strips of different age the overall bee community is thus presumably higher than in landscapes with only annual flower strips, which are very uniform in their flower provision.”

To increase bee populations around their crops, the researchers recommend having flowers throughout the season. One of the easiest ways to do this is by planting strips of perennial flowers along with flowering hedges.

Although the study focused on apple orchards, researchers say the findings can translate to backyard gardens or any other place people want to increase bee populations.

“Yes, absolutely. To boost bee abundance it is crucial to provide a high diversity of flowers (at best native wildflowers) over the entire season,” says von Königslöw. “At the same time nesting possibilities for bees should be available like spots of bare soil and dry plant stems.”