The “Leave the Leaves” campaign has gained momentum in recent years, so in this article, we’re going to break down why it’s important for fallen leaves to be kept in their home yard. Before decomposing and releasing nutrients for plants to grow, winter leaf cover provides habitats for local wildlife. Toward the end of the article, we’ll share some actionable tips that you can use every autumn to create habitats for Nashville’s wildlife, return nutrients to the soil, and get the most out of your tree’s fallen foliage!

Leave Leaf Litter in the Yard

In natural woodlands, leaves and plant debris tend to remain where they fall and decompose in place. In built environments like city neighborhoods and suburbs, however, trees are part of heavily managed landscapes that are dominated by buildings, hard surfaces, grass, gardens, and people. Following the beauty of fall foliage in these areas is the work of cleaning up, or so has been the routine! 

We often rake leaves to clean up the yard to protect the grass, discourage the presence of pests, and give a tidy appearance to the neighborhood. Doing so also allows us to enjoy our yards throughout the year. Some people are avid gardeners and are more active with landscaping, reusing leaves in different parts of the yard as mulch or compost, while others prefer to pack up the yard waste and send it off. We’re increasingly aware of the problems sending leaves away is causing, however, which is why the National Wildlife Foundation’s “Leave the Leaves” campaign seeks to educate and influence environmental stewardship in a residential setting.

There are three fundamental problems being caused by not reintegrating leaves into their immediate ecosystem:

1. Landfill and pollution problems: In 2018, the US Environmental Protection Agency estimated that about 12% of landfill material was composed of yard trimmings. Not only does this take up a significant amount of space, but the organic material rots rather than decomposes, producing methane gas, a potentially hazardous air pollutant. 

2. Decreased wildlife services: The several inches of leaf buildup and plant debris provide important groundcover for small wildlife of all kinds, from salamanders, frogs, turtles, and snails to bees, caterpillars, fireflies, crickets, and many others. These inhabitants feed on the leaf litter and may be prey among themselves or for larger predators like birds and mammals. With increasingly less winter groundcover, population numbers of beneficial insects and invertebrates have been dropping, which has widespread effects on local environments. 

3. Soil quality reduction: Soil is made up of organic material that has been partially or fully decomposed by wildlife, bacteria, and fungi, and it contains varying amounts of oxygen, water, and stone particles. Without leaves, there is less organic material to compose the bulk of the soil, less food and habitat for decomposers, and fewer nutrients available for plants and trees in the ground. 

To reduce these effects, leaving leaves in the yard where they grew aims to support: 

• Wildlife of every kind

• Soil quality and quantity

• Tree health, resulting from nutrient availability and active wildlife inhabitants and visitors

• Ecosystem services produced by mature, healthy trees

What Happens If You Don’t Rake the Leaves?

The “Leave the Leaves” movement is all about working with nature to encourage the best environmental conditions. When we don’t rake the leaves, it benefits the local ecosystem in many ways, but it may have some drawbacks for our human comfort if it’s done wrong and can even be detrimental to the landscape.

The main problems arise from allowing leaf accumulation to become too deep, but since every property is unique, this will vary from yard to yard. Dense leaf cover will smother grass, so yards with cool-season grass like rye or fescue may be less inclined to leave leaves on the lawn over winter, perhaps preferring to use their leaves as mulch or compost before spreading them across the grass. On the other hand, yards with natural spaces or garden beds have many opportunities to incorporate leaves into the yard more easily.

Deep leaf buildup can have other drawbacks as well, particularly as a host to unwanted wildlife. A layer of several inches allows light, oxygen, and foragers to maintain the balance of ground life. However, too-deep accumulation creates dark, moist areas where fungus, slugs, ticks, and other undesirable and potentially harmful pests and diseases can thrive. When leaves sit around for too long in this condition, they don’t break down properly, creating a messy and slippery layer of rot rather than healthy, fluffy soil.

How to Leave the Leaves 

There are many ways to leave the leaves in your yard and support local wildlife without everything becoming too messy. A big yard might not need to be raked at all, while a smaller or more heavily utilized yard may need some attention to make sure fallen leaves are managed in an efficient and ecological way. The main ways to leave the leaves in your yard include:

• Simply leaving the leaves alone where they fall

• Raking leaves into the perimeter directly under the tree (without burying the root flare)

• Raking leaves into three- to five-inch layers under bushes, over garden beds, or into designated natural spaces (particularly spots with perennial stalks and woody shoots where plant debris naturally accumulates)

• Using excess leaves in compost, mulch, or leaf mold to fertilize the soil

Shredding leaves with a mower is discouraged since it can disrupt the creatures that establish themselves in the leaf litter prior to a mowing event. If you have to mow, however, leaves can be raked off to the side to be re-distributed later. If mowing season is over but you have a lot of leaves, consider raking a thin layer across the yard, then incorporating excess leaves into a passive cold compost or leaf mold pile. As with much in environmental management, finding the appropriate tactics and balance for a particular location is key. 

Embrace Your Leaves This Fall

Fall is the start of the tree-planting season! Check out the Nashville Tree Conservation Corps’ tree sale page, where you can find the right tree for your next planting project. If you don’t have the space to plant a tree, you can sign up to volunteer with us or donate a tree for us to plant! A financial donation of any amount helps fund our planting projects and our mission in general, which would be impossible without Nashville’s support! Subscribe to our email newsletter if you haven’t already, and visit our Linktree for more ways to keep in touch with us.