Hidden microclimates attract bees and boost farm yields

Climate usually conjures images of vast regions and decades-long change, but it also shifts over a few miles in a single afternoon.

A team of researchers led by Pennsylvania State University has shown that these microclimates can nudge bees toward particular patches of a field and, in doing so, make or break yields of wild blueberries.

The project unfolded on a 170-acre commercial blueberry operation in coastal Maine, where researchers divided the rolling terrain into 120 one-square-meter plots and then carpeted it with sensors.

Every ten minutes during blossom season, those sensors logged temperature and humidity, while students noted how many blossoms opened, which bees showed up, and how much fruit ultimately ripened on 100 plots.

Microclimates shift bee patterns

Across that single field, conditions proved anything but uniform. Temperature varied by as much as 20 degrees Fahrenheit, and relative humidity differed by nearly 30 percent. The warmest ground also tended to bear more flowers, and bees noticed.

Honey bee foragers trucked in by the grower and wild native bees alike located the most densely blooming areas of the fields and focused their foraging in these areas.

Wild bees, in particular, were warmer-than-average chasers, arriving earlier in the day and flying under a wider range of conditions than their managed counterparts.

Targeting bees with climate data

Those results matter, said lead author Heather Grab, an assistant professor of plant science at Penn State.

“Remote sensing techniques could measure flower density patterns across the field and identify low blooming regions, which may be a promising method for selecting candidate areas to convert to conservation habitats,” she explained.

In other words, growers might pinpoint unproductive corners and swap them out for wildflower strips or nesting sites that bolster pollinators and the crop alike.

Cracking bee yield mysteries

The bee and microclimate study reflects a three-way partnership among Penn State’s Center for Pollinator Research, the University of Pittsburgh, and Wyman’s, one of the nation’s largest wild blueberry companies.

“Our collaborators at Wyman’s noted that some parts of their fields consistently produced fewer berries, but there was no obvious reason,” recalled Christina Grozinger, director of the Huck Institutes of the Life Sciences at Penn State.

“We decided to tackle this mystery by developing new strategies for monitoring and modeling crop yield, pollinator activity, and environmental variation, in collaboration with Vikas Khanna’s group at the University of Pittsburgh.”

“Tackling these issues demands interdisciplinary strategies that integrate knowledge from diverse fields, as demonstrated by this research team,” added Khanna, a professor of civil and environmental engineering in Pittsburgh.

Mapping bees and blossoms

To capture the field’s hidden patterns, Pittsburgh students fanned out with stacks of battery-powered dataloggers.

Over weeks, they verified that warmer niches, often on gentle south-facing slopes, held thicker carpets of blossoms.

They also mapped fifteen honey bee hives and tracked where their tenants flew. The data confirmed that wild bee numbers did not dip near hive clusters, easing fears that managed pollinators squeeze out native ones.

Tiny climates, big effects

The team found that much of the variation could be traced to subtle shifts in temperature and humidity across time and space – changes that played out over the course of a day and among different microclimates within the same field.

Because warmer areas of the field also had more flowers and higher yields, changes to the climate that increase microclimate variability may contribute to increased yield variability within fields.

Globally, bee declines have been tied to sweeping forces such as habitat loss and hotter summers.

Yet this study shows that decisions made at the scale of dozens of meters – where to mow, where to plant shelterbelts, where to turn off irrigation – might tip the balance for both bees and berries.

It also underlines that managed honey bees do not automatically undermine wild pollinators; the two guilds can divide labor across a mosaic of microclimates.

Future farms and pollinator gains

Future work will test whether similar trends unfold on other blueberry farms and in other crops, and whether year-to-year swings in weather shift the sweet spots.

For now, the Maine experiment suggests that seeing a farm through a microclimate lens could help growers optimize production while carving out refuge for native insects.

Remote sensing, smart sensors, and precision agriculture can let farmers manage flowers as well as fruit, which is good news for bees, and ultimately good news for the people who depend on them.

The study is published in the journal Agriculture, Ecosystems & Environment.

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