UBCO study shows flower gardens planted beside fruit crops can double yield if timed right

Photo: Dr. Amanda Liczner, University of Guelph

University of British Columbia Okanagan researchers are studying whether planting flowers to attract pollinators, like bees, could benefit nearby crops.

UBCO researchers Dr. Rebecca Tyson and Dr. Bruno Carturan started by asking the question, "can flowers planted to attract pollinators benefit neighbouring crops?"

“Planting wildflower patches near crop fields is considered a potentially effective strategy to support both the abundance and diversity of pollinators and the services they provide,” says Carturan. “But these management strategies can be costly and not always effective in enhancing crop yield.”

The idea is that planting supplemental gardens can lead to larger and healthier wild bee populations which theoretically should be good for crop pollination. Except that field studies show contradictory results. Some indicate an increase in crop yield directly related to pollination services, while others show no discernible effect at all.

“While the plan makes sense on paper, it can create a conundrum,” Carturan says. “With more bees in the landscape, there is the potential for greater pollination of crop flowers. But bees can prefer different flowers, guided by nectar sugar content, flower shape and pollen nutrient composition. Consequently, the presence of wildflower patches beside a berry crop could divert bees from pollinating the crop.”

The researchers set out to understand the interplay between the relative timing of crop and wildflower bloom, as well as the quantity, quality and relative attractiveness of the flowers.

The study focused specifically on blueberry crops, because bumble bees are known for their superior efficiency in pollinating blueberry flowers compared to honey bees. The researchers wanted to vary the size of the crop area, the size of the planned garden relative to the crop and the relative nutritional quality and bloom time of both the crop and additional flowers.

The result of numerous simulations showed that providing highly nutritious wildflower resources before the crop blooms can more than double the crop yield. On the flip side, providing wildflower resources at the same time as crop bloom can reduce the yield by up to 50 per cent.

“The main result of our virtual experiment clearly shows that the most beneficial strategy is to generate a temporal spillover effect by providing a continuous supply of resources to the bees and avoiding too much competition between the wildflowers and the crop flowers,” Tyson says. “This keeps the bees well fed during the early foraging season when the colonies are growing, and it prevents a potential distraction effect during crop bloom.”

The researchers hope to refine the model with the goal of calibrating the model to help inform planting strategies on a real farm.