A lot of acorns this fall might mean it’s a ‘mast’ year
Associated Press
This Oct. 4 image provided by The Morton Arboretum shows an abundance of fallen acorns under an oak tree in Lisle, Ill.
Associated Press
This Oct. 22 image provided by Julia Rubin shows black walnuts under a tree in Westchester, N.Y. Walnut and other fruit- and nut-bearing trees produce bumper crops every two or more years in tandem with other trees of their same species in a particular region. No one really knows why.
Associated Press
This Sept 12 image provided by The Morton Arboretum shows a white oak tree bearing a bumper crop of acorns during a mast year in Lisle, Ill.
Has your car been getting pelted with acorns? Have you found yourself running through a hailstorm of walnuts with your hands protecting your head? Chances are the trees in your region are experiencing a mast year.
Nut-bearing trees, such as black walnuts, beeches and those acorn-producing oaks, have 鈥渙n鈥� and 鈥渙ff鈥� years. 鈥淥n鈥� years, called mast years, see vigorous production of nuts across an entire species throughout a region.
During mast years, a single oak can drop thousands of acorns, forcing you to rake your lawn even before any leaves drop, or sweep your driveway to avoid twisting your ankle while navigating a blanket of marbles.
After expending all that energy on an abundant crop, the trees take a break, producing few if any nuts during 鈥渙ff鈥� years.
The cycles for mature red oaks and black walnuts typically run two to five years; pecans tend to alternate between boom and bust, often taking just one year off. Most fruit and nut trees undergo these cycles, although each species has its own timeline. And even then, their schedules are not set in stone.
鈥淭here鈥檚 no general consensus (among scientists) on why we see these mast years,鈥� according to Jonathan M. Lehrer, associate professor and chair of the Department of Urban Horticulture and Design at Farmingdale State College in New York. 鈥淭here鈥檚 a lot of conjecture that it鈥檚 caused by variations in temperature and natural rainfall, but we鈥檝e never been able to hammer out exactly why some years have greater production than others.鈥�
And on up the food chain
Mast years help to ensure the propagation of a tree species because at least some of those acorns and nuts, which contain seeds, take root and grow into saplings.
The phenomenon also affects the wildlife population, as bumper crops during mast years provide abundant food for woodpeckers, deer, mice, wild turkeys, squirrels and other animals, resulting in more breeding. Less food during off years tends to keep those populations in check.
鈥淭he production of trees has far-reaching consequences on wildlife and other organisms, and fewer rodents (during off years) affects larger animals higher on the food chain, like foxes, owls and bobcats,鈥� Lehrer said. 鈥淎lthough an abundance of acorns may be a nuisance, the ecological consequences of a mast year can extend for a year or two or three afterward.鈥�
The reasons and stimuli for the cycles may be unknown, but one thing is clear: 鈥淎s plants go, we go,鈥� Lehrer said.
So, if you鈥檙e finding yourself ducking for cover, take precautions: Avoid parking under masting trees to protect your car. Take care when walking so as not to slip or trip. And, most importantly, remember to look up!
Jessica Damiano writes the award-winning Weekly Dirt Newsletter and regular gardening columns for the AP.