Welcome back to Birdbrained Science! After discussing odd animal-derived substances last week (for now), we’re going back to natural phenomena for this edition.
A few weeks ago, we talked about what’s going on when leaves don’t fall. Today, I’m going to talk about what happens after they do.
If you grew up with a substantial yard in New England, you might have memories of your parents raking up leaves into large piles and then jumping into them (or, in my case, jumping in and then being disappointed that it was kind of just cold and slimy and not as fun as you’d thought it’d be). You also might have memories of your parents putting all those lovely leaves into black garage bags and then tossing them out. And you probably didn’t think anything of it — after all, they’re just dead leaves, right?
And yeah, they kind of are — in the same way that your house might just be dead wood. Lots of little critters make their homes in what’s referred to as “leaf litter” — a layer of fallen leaves, twigs and other organic bits and bobs. Leaf litter, especially during the winter, is a hotspot of activity and holds an important ecological role for lots of organisms. There are lots of different kinds of little guys that spend time in leaf litter, such as bacteria and fungi. There are also lots of invertebrates (meaning that they have no spine) in the litter, such as firefly larvae, spiders, earthworms, snails, millipedes, beetles, bees and moths. These creatures hang out in the leaves, taking on various different forms. For instance, the Luna moth spends its winters in cocoons hiding among the leaf piles. Lots of other different butterflies and moths lay their eggs in the litter. Tardigrades (also known as water bears) take the form of eggs and cysts (a tough outer shell) when living in leaf litter.
Different creatures in the litter also partake in different activities. For example, worms, snails and millipedes actually eat some of the litter, which breaks it down into smaller pieces. Smaller pieces of leaf litter are easier for bacteria and fungi to break down into chemicals and minerals like nitrogen, calcium and sulfur, which are used to nourish trees and other plants.
On the larger side of things, bigger animals (with backbones) also have uses for leaf litter. Salamanders, mice, snakes, turtles and toads rely on litter to both hide from predators and to find food. Even larger animals, like birds and larger mammals, will visit leaf litter to eat the smaller vertebrates in return. So, leaf piles are pretty much entire circles of life, taking place right in your backyard. Nearly every kind of organism you can think of — vertebrates, invertebrates, trees, fungi, bacteria and more — benefits from leaf litter.
The bottom line for today: pay attention to where you step. You never know what worlds could be hiding right underneath your feet.
Also, consider doing your neighborhood crawlies a favor and leaving the leaves out. You don’t have to leave them exactly where they fell — you can rake them into big piles onto the edges of your lawn, but please don’t throw them out. Because, really, what are lawn aesthetics against the potential of life?