According to the Oak Park Public Works Department, the village annually collects an average 2,850 tons of leaves at a cost of about $193,000. That's a lot of leaves and money (not to mention a lot of leafblowers). Then we individually spend more money and consume more fuel purchasing and transporting fertilizer and mulch, not to mention the production and packaging of the fertilizer and mulch.There is a more sustainable and ecologically-minded solution.
Healthier soil results in healthier plants, more able to fend off various stresses. If we stockpile the leaves, then we also have free mulch next year to continue to improve the soil, increase water retention, and regulate soil temperatures. Leaf mulch in the garden or around shrubs and trees acts like a sponge, so during times of high rainfalls, the leaf layer absorbs the rain and allows the rainwater to percolate more slowly through the soil instead of into the sewer system.
Another little-known benefit to retaining leaves is that most of our butterflies, native bees, and other insects overwinter in the leaf litter or garden debris. Most butterflies and moths (including those beautiful Luna, Cecropia, and Polyphemous moths) spend their time as caterpillars or as pupae during the winter. Allowing the leaves to remain in the garden or in a pile will likely help to increase our native insect population, many of which are important as pollinators.
Additionally, birds that migrate or are permanent residents also appreciate an increase in insect populations. Birds turn over the leaf layer, searching for food and enjoy the increased insect population in the spring as the overwintering insects complete their life cycles — 95% of birds feed insects to their young, and with the increased pressure on birds and nearly all species of animals, we should strive as a community to compensate for their habitat loss. We need to recognize that an increase in biodiversity is good for sustainability, an initiative that many Oak Parkers support.
The amount of leaves dropped can be overwhelming, and we do have small yards, but it is possible to keep the leaves. Last year my family was able to retain most of the leaves from our 80-plus-year-old Norway Maple, as well as all of the other garden debris in our very small yard. We simply put the leaves under bushes (away from the trunks), in an area for passive composting, and on the garden beds.
In the spring, the piles had reduced dramatically from a height of 18 inches to an inch or two. By July, I was wishing I had more leaf mulch and collected leaves from parkway trees that were dropping leaves to cover the bare soil in my gardens. All of the soil beneath the leaf mulch is loose and rich thanks to the sizable earthworm population, as well as the rest of the under-appreciated millions of decomposing organisms.
Another strategy for dealing with the volume of leaf litter (but one that would defeat the purpose of allowing next year's butterflies and moths to complete their life cycles in the spring) is to simply mow over the leaves and leave the leaf mulch on your lawn. It's a simple and inexpensive way to build a healthier lawn.
Keeping the leaves in the yard is a fairly simple and easy thing to do to benefit ourselves and our pocketbooks (no need to pay for fertilizer or for mulch). It reduces the burden on the village with associated decreases in pollution and oil consumption. Creatures benefit too: butterflies, bees, and other beneficial insects (yes, insect pests could survive too but in a healthy ecosystem beneficials keep them in check). It's a sustainable thing to do, resulting in increased beauty and a healthier ecosystem we all share.
For those interested in soil organisms, visit this Soil Biology Primer: http://soils.usda.gov/sqi/concepts/soil_biology/soil_food_web.html