Roots and Shoots: Life Under the Leaves

Lots of life is happening under those fallen leaves. Photo by P. Doan

Lots of life is happening under those fallen leaves. (Photo by P. Doan)

I was an early adopter of the “leave-the-leaves” approach to the fall landscape, easily convinced that gas-powered leaf blowers were polluting and unnecessary and that the time-consuming task of managing leaves on a heavily wooded property was damaging and futile.

As I’ve created more habitats for insects, birds and wildlife, I’ve become more curious about what and who is around and why they show up. 

There’s a lot going on in what looks and sounds like a quiet yard out there. Beneath the leaves, in the soil, in the crevices of decomposing logs, invertebrates are finding their places to survive the winter. 

By now, if you’re still insisting on a clean-swept lawn while all the evidence points to the necessity of leaf cover, this column probably won’t change any minds. For others who are simply following the pervasive culture of 40 million acres tended by American lawn owners, maybe understanding what’s at stake will help shift your practices. 

First, understand that a layer of leaves doesn’t kill the grass underneath unless it’s thick, like more than 2 inches. A thick, matted layer of more than 2 inches left on the lawn in the spring when the grass is no longer dormant should be mulched in, loosened or raked away to allow for growth. Over the winter, though, it’s not a big deal. The grass is dormant. 

Insects, the foundation of our ecosystem, many of which provide pollination for the majority of the food we need, use our lawns to survive the winter. The marvel of the monarch migration is well known and understood, yet most of the butterflies, moths and bees that populate our landscapes have developed strategies to stay in place. 

Fallen leaves protect insects in every stage of life — as adults, chrysalises, eggs and larva. The Xerces Society, in an online resource about overwintering habitat, shares an example of the red-banded hairstreak butterfly that lays its eggs on fallen oak leaves. When the caterpillars emerge in spring, the leaves are their first food source. If you’re bagging up all those leaves and dumping them at the curb, it’s unlikely the cycle will be completed. 

The cocoons of luna moths and the chrysalises of swallowtail butterflies evolved to protect them during their winter hibernation by resembling a fallen leaf and blending in. Those cute woolly bear caterpillars need to hide in the leaves, too. 

Spiders, millipedes and snails, all of which are food for wildlife, find spots under the leaves for the winter. During our ever more frequent cycles of freezing and thawing, they become important energy sources for any creature that needs invertebrates for survival, including chipmunks, birds and amphibians. 

Under the soil, some bees will be found burrowed into the ground as well as in brush piles, tree cavities and decomposing logs. The dried out stalks of perennial flowers? Those are used for nesting and larva. 

If tidying up a garden bed is important to your aesthetic, consider not cutting the flower stalks to the ground and maintain a 6- to 8-inch border, instead. The dead seed heads also make a great food source for birds. 

I love watching finches feasting on the globe thistle (Echinops spp.) seeds. While not native to our area, this thistle is a great source for pollinators and birds, and not invasive. Stalks from Echinacea, Rudbeckia, Joe-pye weed and many other plants will suffice, too. 

Finally, here is a rundown of what else to do with your leaves while you’re leaving them alone.

  • Mulch into the lawn while mowing to add organic matter to the soil and prevent moisture loss. 
  • Allow landscaped beds to be covered in leaves. The plants will find their way through in the spring. 
  • Let leaves be mulch around trees and shrubs to add organic matter to the soil, retain water and suppress weeds. 
  • Use leaves in the compost pile as a “brown,” a carbon-rich ingredient. 
  • Wait until late spring to move leaves around if you have to, but remember that there is always something living in that ground cover and try to disturb it as little as possible. 

Now go enjoy the time that you aren’t doing fall cleanup in the yard and buy yourself some plants with the money you aren’t spending on a lawn service. 

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