Jun. 10—If you think you've been seeing an invasion of helicopters this year, you're not imagining things.
Southern Minnesota maple trees are producing a copious amount of seeds that flutter from their branches on stiff, light blades called samaras.
"If you think you're seeing more of those this year, your observations are correct," said Angela Gupta, an educator and forester with the University of Minnesota Extension.
Gupta said foresters aren't in agreement why this happens every few years, but it's a regional phenomenon that doesn't appear to be tied to the weather.
"I think foresters wish we understood it better," she said.
Gupta said it may be an adaptation to the foragers that feed on maple seeds each year.
Maples have a baseline volume of seeds they produce each year. Most of those seeds are eaten by squirrels, chipmunks and other critters.
Every few years, maples produce a glut of seeds, which gives the trees a better chance of producing viable seedlings — and the seed eaters likely more than enough food.
"The theory is that they overwhelm the critters that will eat the seeds," Gupta said.
Other species of trees have similar (but more predictable) cycles of mass seed production. White oak and red oak trees will produce more acorns in certain years.
"It's a common approach," she said.
The foragers that feed on seeds usually do well after a year of higher seed load. Their populations tend to go up in the months after an uptick in seeds. Then comes a bumper year for predators.
"There's a kind of ripple effect that happens," Gupta said.
But, she added, what sets that cycle into motion is still unknown.
"It just speaks to the mysteries of the ecosystem," she said.
Sometimes it's nice not to have all the answers and to just contemplate the question.
Emilio DeGrazia's book "What Trees Know" is a collection of poems that does just that. It's a beautiful and contemplative read.
Rochester Civic Theatre is staging a reading of the work July 14 for a fundraising event. More information and ticket availability will be released soon.
For now, ponder the poplar, contemplate a cottonwood, and pull those maple starters out of your garden, gutters, potted plants, and anywhere else you find them.
John Molseed is a tree-hugging Minnesota transplant making his way through his state parks passport. This column is a space for stories of people doing their part (and more) to keep Minnesota green. Send questions, comments and suggestions to email@example.com.