Tuesday, June 10, 2014

The Mini Maple Forest In Your Lawn

0836MapleSeedlingLawn3003BPWMy lawn is a vast Lilliputian forest of two-inch tall trees, a carpet of closed-canopy maple seedlings punctuated by dandelions. It’s hard to tell, but a few blades of grass may have survived. Anyone with large maple trees in their yard probably has a lawn in similar condition. So what happened?

It all comes down to stress. Not the stress you feel trying to figure out what to do with 10,000 tree seedlings per acre (a fair estimation, by the way), but rather stress the trees felt when they ran out of water in 2012. That summer saw the driest soil conditions on record in northern NY, and trees really felt it.

Dr. George Hudler from Cornell’s Plant Pathology Department says that in a summer like 2012, trees suffer extensive root death, and that it takes them two to three years of good conditions to recover from that stress.

And stress, as everyone knows, causes ‘helicopters,’ the name kids give to maple seeds because they whirl through the air as they fall.

In 2013, most trees produced what’s known as a distress crop, creating many times the normal amount of seeds. Apparently this is some kind of evolutionary response, a bid to perpetuate the species in the face of potentially lethal conditions.

MapleKeysCornellDNR3002Sugar maples and red (soft) maples alike, along with their much-maligned cousins the boxelders, cranked out “helicopter” seeds at a rate that would make Sikorsky, Airbus and Bell envious.

The purpose of maple helicopters, of course, is to fly. The winged seeds, technically known as samaras, did just that, insinuating themselves into every flowerpot and sidewalk crack, not to mention onto many lawns. And there they’ve sprouted quite nicely, saving their species from extinction in superlative fashion but creating trouble for gardens and lawns.

That’s what happened—now what can one do about it?

Since we’ve never before seen this heavy of a seed crop, it’s unclear how great an impact the baby forests may have on lawns. In my case it seems they’re shading out the grass in some spots, but when I cut at the recommended three-inch mower setting, most of the seedlings were unscathed.

Although a three-inch setting is optimal for lawn health, it may be advisable to break the rule for one or two early cuttings to remove the maple “umbrella” and let the grasses get ahead. Once the trees have been weakened by close mowing, switch back to the higher setting to allow the grasses to shade out the forest. This is the best strategy general weed control, but since maples are more shade-tolerant than most weeds, it’s unclear how effectively they’ll be suppressed.

If my mowing strategy doesn’t control the maple patch that used to be my lawn, I’m going to call the New York State Department of Environmental Conservation and ask if there’s a forest-management plan for producing toothpicks. I’ll let you know how that works out.

Photos: Maple seedling, photo courtesy Brian P. Whattam; Maple “helicopters,” Cornell University Dept. of Natural Resources.


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Paul Hetzler has been an ISA Certified Arborist since 1996. His work has appeared in the medical journal The Lancet, as well as Highlights for Children Magazine.You can read more of his work at PaulHetzlerNature.org or by picking up a copy of his book Shady Characters: Plant Vampires, Caterpillar Soup, Leprechaun Trees and Other Hilarities of the Natural World

4 Responses

  1. Paul says:

    Paul, great article. The number of maple seedlings under the big old maple tree in my front yard this year was unbelievable!

  2. Marisa Muratori says:

    So that’s what it is..!

  3. Sherri says:

    I have two huge maples in my yard and the past week there has been a torrential downfall of “helicopters.” I have a metal roof so it’s been sounding like it’s sleeting out every time the wind blows.

  4. AG says:

    Well part of the problem is having a lawn of only grass is human folly… There is nothing natural about it.

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