The season of autumn offers a spectacular display of color wherever deciduous trees are in abundance. The trees signal the end of their growing season as their leaves shed the green of summer for the subtle autumn hues of red, yellow and orange. The splash of brilliant fall color ends abruptly, as the leaves turn brown.
Leaves remain attached to branches for varying lengths of time, with oak leaves lingering the longest. In the forest, the leaves continue providing service to the environment after they drop to the ground, which they cover for the entire year.
Many species of birds, including northern flickers, ovenbirds, sparrows and thrushes, forage in the leaf litter. The litter provides food for 70 species of moths that consume the leaves, including the striking banded hairstreak butterfly. It provides cover for the caterpillars that spin cocoons in the leaves. The leaf litter protects and enriches soil community, on which the life of the forest depends.
In neighborhoods where the same trees found in the woods are sparsely planted among rows of houses, trees drop their leaves in the same manner they do in the forest. Property owners then face the question about what to do with the leaves. One option is to mow the leaves. Leaf litter under neighborhood trees performs the same functions as it does in the forest. Mowing reduces that function, as mowing shortens the life span of the leaves. Shredded leaves usually disintegrate before the year is out, leaving bare soil. Enrichment of the soil is negligible, and benefits to wildlife disappear.
Mowing leaves provides minimal ecological service, but mowing is a better alternative than burning leaves or setting them out for the landfill.
For properties where trees grow over turfgrass lawns, a better option to mowing is to rake the leaves into piles around the trunks of the trees. This serves as a no-cost replacement for mulch, provides important nutrition for the trees and offers some benefit to wildlife.
Although the mowing of leaves in fall has been around for a while, it may be time to reconsider that tradition. The natural community under your trees will be grateful if you decide to let leaves continue on the course they followed for millions of years.
Steve Cottrell is a Delaware native and president of the Delaware Audubon Society. He is active in natural area-restoration projects in New Castle County, providing and protecting habitats for birds.
