Should We Really Be Raking Our Leaves...?

Oct 21, 2019

To rake or not to rake, that is the question.

The Masked Biologist touts the merits of mulching your leaves in this week’s Wildlife Matters.

As a child growing up in rural northeast Wisconsin, I loved the fall. It always has been my favorite season; the cool evenings, the crisp mornings, the warm days, the colorful leaves, I love everything about it. While we never really enjoyed our chores, admittedly raking leaves was one chore I didn’t mind because we would get to play around in the leaf piles for a while…before dad burned them. My dad was raised in a family of farmers. They burned ditches in the spring and leaf piles in the fall. The lawns were green, crisp and manicured because that is just the way it was done.

As I have grown up, and rented or owned homes, I found myself tussling with the leaves. By this time, burning leaves was illegal, so we either had to rake them into the road for the street sweeper or rake them up into bags to be collected. The joy of dealing with leaves was gone, long gone. It became more of a senseless chore. I started to try to read up on the topic, and decided their had to be a better way.

In the forest, leaves have a very important role. Obviously, while on the tree, they photosynthesize, making the sugars and nutrients needed by the rest of the tree. Then the tree extracts the sugars and the leaves turn colors and drop off. Once on the forest floor, they form the top layer of the O horizon, the organic layer of decomposing duff that rests on top of the soil. The O horizon houses a variety of invertebrates (insects and worms), fungae and bacteria that help convert the leaves to a nutrient rich compost-like material. This layer also helps amphibians seek cover from the sun, and helps keep their skin moist. It also serves as a nursery for seeds of native plants that need the right amount of moisture and nutrients to germinate and thrive. When your forest loses its organic horizon, it suffers. Precipitation runs off instead of being caught and soaked up like a sponge. You lose the invertebrates that need that organic layer to survive. Non-native aggressive plant species can establish and spread in conditions that are less suitable for native species.

What about your lawn, though? My dad always taught me that the lawn couldn’t have the leaves on top, that the grass needed to breathe. To an extent, my dad was right—I mean, if we didn’t do something with the leaves under our trees, we would see spots of grass that started to die. However, I have learned over time that running over the leaves a couple of times with a mulching push mower can help reduce that concern. The mulched up leaves and grass clippings are great for holding moisture and adding nutrients to the soil. Now that doesn’t mean we don’t do any raking. We have an enormous oak tree that drops so many leaves on our little yard that we simply have to collect the leaves that land on the driveway, roofs, deck, and so on. Just raking up those leaves generates about a hundred cubic feet of yard waste a year. We haul it to the landfill and pay to have them made into commercial grade compost.

There is nothing wrong with raking your leaves, but before you tackle this annual chore this year, consider if there are parts of your lawn, yard or acreage where you might be able to leave some sticks and leaves to slowly decompose. It will help our local salamanders, and you might be able to find a few red worms in there next spring when you are ready to head out fishing.

Striving to make new things familiar and familiar things new, this is the masked biologist coming to you from the heart of Wisconsin’s great Northwoods.