Autumn is in full swing in communities across the United States, making your sidewalk stroll or mountain hike a little more colorful.
But some view fallen foliage as a mess to be conquered rather than a source of crunchy delight.
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Experts say the hallmark of autumnal lawn care — attempting to do away with each leaf that falls on a person’s property — comes with an ecological price.
“Leaves are often thrown out — they’re treated as trash,” said Matthew Shepherd, director of outreach and education at the Xerces Society for Invertebrate Conservation. By raking and bagging them all up, “we are inadvertently impoverishing our landscapes.”
Lawns make up millions of acres of land in the U.S., and Americans use quite a lot of resources to maintain them. But there are plenty of ways to put an abundance of leaves to good use if homeowners opt to work with nature rather than against it, advocates say.
Fallen leaves provide habitat for animals
A thick layer of leaves may not look like much, especially when the color is drained to a dull brown. But chances are it’s actually teeming with wildlife.
As temperatures drop, fallen leaves and the soil underneath offer crucial habitat for all kinds of creatures, including salamanders, frogs and rodents. Shepherd noted that this shelter is especially important for the smallest animals, mainly insects and other invertebrates. That list includes cocooned moths and bumblebee queens, as well as those that might be less eye-catching to humans.
Data suggests that one square meter of leaf litter could house between 40,000 to 50,000 springtails, tiny arthropods that are easy to overlook but important to ecosystems. Trashing leaves takes away an important source of protection for these and other critters in the colder months.
“If we took the roof off our house, we’d be really cold in the winter. If we leave the leaves, we’re leaving the roof of the homes of all those insects,” Shepherd added.
Leaf litter is also a destination for non-migrating birds like cardinals, who hop around feasting on the sheltering bugs below.
In Shepherd’s garden, he leaves flower stems and seed heads standing, providing both extra groundcover and food options for wildlife. He gets the benefit of watching the birds over the fall and winter, an entertaining show from the warm indoors.
“There’s a lot of life that you bring into your yard simply by not tidying up,” he said.
Fallen leaves are rich with nutrients
Dead leaves play a major role in infusing soil with new nutrients. The invertebrates that come along to munch on the leaves start the process of breaking them down before microbes help finish the job.
When trees take in carbon dioxide in order to photosynthesize, it’s stored in their bark, trunks, roots, as well as their leaves, said Theresa Crimmins, director of the USA National Phenology Network.
The leaves that trees shed in autumn release some carbon dioxide into the atmosphere as they decay, but carbon is also ingested by the organisms that feed on the leaves. That includes earthworms, she noted, whose excrement is “essentially soil.”
Beyond worm food, leaves are a great natural mulch on flower beds until it’s time to prep your garden for the next growing season. They are really important for soil because they add “organic matter — which can help with moisture retention — they add nitrogen back into the soil, and they also can play an important role in suppressing weeds,” Crimmins said.
Trashing or burning yard waste contributes to pollution
Whisking away fallen leaves isn’t just a detriment to your local insect population – it can also contribute to planet-warming greenhouse gas emissions.
Yard waste, which includes discarded leaves, makes up about 12 percent of all municipal solid waste in the U.S. A majority of that waste is composted, which is a good thing — but nearly a third of it ends up in landfills, Gregory Keoleian, director of the Center for Sustainable Systems at the University of Michigan, told the PBS NewsHour via email.
When those leaves are left to rot in landfills, he explained, they release methane due to the anaerobic bacteria that thrives in that oxygen-poor environment.
Burning leaf piles is another popular solution for getting rid of leaves, but it comes with its own dangers. For one, burning any materials presents a fire hazard, which is why people in dry areas should take particular caution when doing so. Burning leaves also releases particulates and toxic chemicals that can be particularly harmful to those with respiratory issues, Keoleian noted.
“Burning anything creates low-level pollution,” said Beth Clawson, an extension educator at Michigan State University.
She added that when fires burn close to the ground, that smoke stays close instead of mostly traveling further up into the atmosphere. That’s why smoke stacks at factories have to be fairly tall, Clawson said — so that there’s less opportunity for their emissions to reach people directly.
Tips for fall lawn management
If you’re not totally sold on surrendering to the leaves, don’t feel too guilty. No one expects homeowners to make the binary choice between cultivating the very tidiest yard or a completely wild one, Shepherd said.
Instead, advocates say, determining where leaves can be left alone and which spots you want cleaned up can help you strike a reasonable compromise between home maintenance and land stewardship.
“It comes down to reaching that balance between which areas of your yard do you want your kids to play in and do you want to sit in, and so on? And which areas of your yard can be allowed to be more natural?” Shepherd added.
Here are a few more quick tips from the experts:
- Check if your community offers composting. If it doesn’t, consider starting your own pile on your property.
- Rake or use electric leaf blowers, if you can. Those two options are better for the environment compared to gas-powered leaf blowers, Keoleian said.
- You could use a leaf shredder or shred leaves with a lawn mower, but… While those leaves make a good mulch or natural fertilizer, the shredding process would unfortunately be a mass casualty event for all the insects that settled in those leaves, Shepherd noted.
- Help researchers track fall changes. The National Phenology Network invites people to report observations of animals and plants — including leaf drops — year-round using a tool called Nature’s Notebook to help policymakers make decisions.
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