What Impacts Acorn Production in Oak Trees?

Acorns come from oak trees, and their production varies year over year and per location. Oak trees in one area and climate might be considered a bumper crop, meaning they produce an especially large amount of acorns. Meanwhile, in another location, oak trees might hardly produce any acorns.

What causes this vast difference in acorn production? Here, we review different oak tree production patterns and what a decrease in acorn production says about the tree's health.

Oak Trees and Weather Patterns

Oak trees and acorn production are impacted by the weather, according to Kim Coder, a professor of tree biology and health care in the Warnell School of Forestry and Natural Resources at the University of Georgia. The primary weather factors influencing nut production are spring frosts, summer droughts, and fall rains.

Trees have what Coder calls "inside timers" that tell them to do different things at different times, such as when to flower and hold fruit. The changing temperatures and day length factor into how many acorns any single tree produces, as do other variables. Coder noted that some oaks will always have a substantial acorn crop so long as the weather cooperates.

A common term for high-production years is a mast year, meaning the tree produces a surplus of food. Weather, not the tree itself, is often the driving force behind this large harvest.

The internal timers tell the trees to open their buds in the spring after the danger of frost has passed. Once the buds flower, the blooms are open for only a week, during which they are pollinated by the wind. However, a late frost will stop the flowering process. If that happens, the results show up in the fall with greatly limited nut production regardless of what happens with the weather in the summer and autumn.

Even if there is a good spring fruit set, summer droughts can cause acorn fungal problems that can limit production. On the other hand, significant rain during the fall can get the trees ready for a great flowering next spring. Coder noted that this is an example of how nut trees are one year behind in the climate process that affects how much mast they produce.

Microclimates and Acorn Production

Microclimates—localized climate conditions separate from other areas—also affect nut production. The localized climate conditions that apply to the oak trees in your neighborhood probably wouldn't apply to a place 100 miles from where you live, noted Coder.

Along with microclimates, acorn production can be impacted by the size of the oak tree as well as microsite characteristics, like soil depth and topography.

Impact on Ecosystem

Variations in mast can noticeably affect the ecosystem. Depending upon animal reproduction cycles, excess food can lead to surges in the populations of rodents, small and large mammals, and birds. The impact of these population increases can potentially affect humans, too. An increase in the number of mice and deer, for example, can cause an increase in ticks in a given area