Honey production declines: study links changes in soil, climate, & land use

Honey production from beehives in the U.S. has dropped a lot since the 1990s. This could mean there are fewer flowers for bees to get pollen and nectar from, which would affect all pollinating insects, not just honey bees.

Researchers looked at data from across the U.S. over 50 years to see what might be causing this. They found that the type of soil and climate in a region set the basic levels of honey production. But the use of weed killers, changes in how land is used, and changes in weather patterns also affected how much honey was produced each year. These findings can help develop ways to make flowering plants and pollinator species more resilient.

Weed killers, land use affect honey

A study published in the Environmental Research journal found that changes in honey production over time were linked to the use of weed killers and changes in land use. For example, there were fewer programs to conserve land and support pollinators. Changes in weather from year to year also affected honey production.

The researchers used data from several open-source databases, including ones run by the U.S. Department of Agriculture. The included data contained things like the average amount of honey each bee colony produced, the way we use land, our use of weed killers, climate, changes in weather, and the productivity of the soil in the U.S.

The researchers found that climate conditions and how productive the soil is were some of the most important factors in estimating honey production. States with both warm and cool climates produced more honey when they had productive soils.

The researchers concluded that the type of soil and climate in a region set the basic levels of honey production. But changes in land use, the use of weed killers, and weather also impacted the annual honey production.

The lead author of the study and a National Science Foundation (NSF) postdoctoral research fellow in Penn State’s Department of Entomology and Center for Pollinator Research, Gabriela Quinlan, said that attending beekeeper meetings and conferences and repeatedly hearing the same comment: "You just can’t make honey like you used to," inspired her to conduct the study.

Climate change impacts honey production

Quinlan said, “We're uncertain about how climate change will continue to affect honey production. However, our findings may aid in predicting these changes. For instance, as the climate warms and becomes more moderate, pollinator resources in the Great Plains might dwindle. Conversely, as conditions become hotter, resources might expand in the mid-Atlantic.”

Christina Grozinger, a co-author on the paper and Publius Vergilius Maro professor of Entomology and director of the Center for Pollinator Research, said that while scientists knew that many factors influence the abundance of flowering plants and flower production, they previously only conducted prior studies in one region of the U.S.

She said, 'What really distinguishes this study is our ability to utilize 50 years worth of continental U.S. data. This equips us to thoroughly examine the impact of soil, eco-regional climate conditions, annual weather variation, land use, and land management practices on the availability of nectar for honey bees and other pollinators.'"

The researchers state that a lack of flowers providing enough pollen and nectar for food is one of the biggest stressors to pollinators. They also point out that different regions, due to their climate and soil characteristics, can support different flowering plants. Therefore, they note a growing interest in identifying regions and landscapes that have enough flowers to be friendly to bees.

Flower scarcity stresses pollinators, bees

“A lot of factors affect honey production, but a main one is the availability of flowers,” she said. “Honey bees are really good foragers, collecting nectar from a variety of flowering plants and turning that nectar into honey. I was curious that if beekeepers are seeing less honey, does that mean there are fewer floral resources available to pollinators overall? And if so, what environmental factors were causing this change?”

Quinlan found one of the most exciting discoveries to be the importance of soil productivity, an under-explored factor in analyzing the suitability of different landscapes for pollinators, according to her. Many studies have analyzed the importance of nutrients in the soil, but there has been less research on the influence of soil characteristics like temperature, texture, and structure, properties that determine productivity, on pollinator resources.

The researchers also found that when soybean land decreased and Conservation Reserve Program land increased, it resulted in positive effects on honey yields. The national conservation program, The Conservation Reserve Program, has shown support for pollinators.

The importance of herbicide application rates in predicting honey yields also appeared potentially because removing flowering weeds can reduce nutritional sources available to bees.

"Quinlan said that their findings provide valuable insights. We can apply these insights to improve models and design experiments. This will enable beekeepers to predict honey yields, help growers understand pollination services, and support land managers in aiding plant-pollinator communities as well as ecosystem services".

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