Saturday, May 13, 2023

Nature’s litter: not just stuff underfoot – the unseen value of detritus


New and old Live Oak leaves in late spring.

It all started with oaks.  Some time ago, I sketched a favorite tree and wrote about oaks as akeystone species, and why fallen leaves are important to their habitat.  I’m much more aware of leaf cycles now.  In my neighborhood and beyond, live oaks dropped their tired leaves this spring and new leaves emerged, bright and sassy.  As we move into summer they’re turning a darker, more sedate color.  Deciding on the actual color of live oak leaves is a challenge for me – as a whole, tree foliage seems to be a muted dark olive at times; other times there is a hint of blue in the green.  Up close they vary.  Besides enjoying the puzzle of how to accurately sketch leaf colors, I’m looking at fallen leaves and all the bits and pieces that make up the leaf litter under trees.  

Treasures under the oak tree.

 I’ve been reading learning about the value of fallen leaves to ecosystems in general and realize this is an invisible chunk of the natural world I often overlook.  Yes, I know that leaf litter is important, but until I started to educate myself more deeply, I didn’t realize how vital it is to the health of food chains.  In practice, I let fallen leaves lie (in most places) most of the time, unless they pose a fire risk.  But now this industrious hidden world kindles my curiosity and wonder.  Imagine!  An entire food web depends on the untidy clutter of nature’s litter.

 Natural litter (as opposed to human litter) is organic material such as dead leaves, twigs, branches, seedheads, husks, berries, and grasses.  We can find leaf litter on the forest floor, in streams, rivers, and bays, and under our cultivated trees and shrubs (if not raked away).   In my backyard litter, I’ve seen earthworms, mushrooms, spiders, beetles, millipedes, cicadas, snails, ants, caterpillars, anoles, centipedes, toads, grubs, crabs, and small snakes, not to mention MANY unidentified insects.  Fungi loves leaf litter too – mushrooms, puff balls, and bracket fungi often make their home there.

Leaf (needle?) litter under the slash pines. Pine needles are actually modified leaves.

 Besides sheltering many species, this leaf layer conserves moisture and protects the soil below.  Vulnerable creatures can find a home or a hiding place from predators.  Some moths make cocoons that mimic the same dried leaves they nestle into for their change from caterpillar to moth.  A small snake or anole can quickly and easily vanish into the leaves or brush piles.  Litter hangs around a while, decomposing slowly through the action of weathering and digestion.  Temperature and humidity affect the decaying process, and all sorts of living things feed on (and excrete) the nutrients locked inside.  

 Living in the leaf layer are small consumers that also de-construct – they help break apart larger bits such as leaves, twigs, branches, and berries.  A wide variety of worms and insects make their homes in the earth below, some for their entire lifespan.  Cicadas spend years underground before emerging to mate.  Underground dwellers aerate the soil as they burrow and leave their waste for others to feed on.  Bacteria and underground fungi further decompose the smaller bits into nutrients that feed the plants and trees that initially produced them. 

 These tiny life forms are part of the base of our food webs.  Dr. Doug Tallamy, author, entomologist, and conservationist, reminds us that "All animals get their energy directly from plants or by eating something that has already eaten a plant.  The group of animals most responsible for passing energy from plants to the animals that can’t eat plants is insects.”

For example, birds forage for insects and worms and other edibles among decaying leaves.  For many birds, this is their primary source of food.  Just think of the larger life forms that depend on birds for their diet and so on up the food chain – and it all starts with plants and their litter.  

 We have a lot of thanks to give to the many thousands of (or more) insects and other invertebrates that make their homes in the ground and the decomposing layer of litter covering it.  Every minute, they’re busy tidying up and transforming raw material into usable energy.  It may have been the oaks that started it, but there are so many more species contributing their own litter.  I’m more careful now about raking away the leaves, pine needles, twigs and such, and find myself checking under every tree and bush for a glimpse of that mysterious underground universe. 

 For more exploration:

University of FL/IFAS blog, an interesting read on the value of leaf litter in Florida:

  “Life in the Leaf Litter” from the American Museum of Natural History, a downloadable PDF booklet with engaging text and illustrations:

Things that go squirm in the night... a 3 minute video from

  Slash pine litter coloring page: download a PDF.

Aquabee sketchbook, 6x9”
.7 mm mechanical pencil
Pitt Pen, Sepia F and Micron Pigma, black 01
Mondeluz watercolor pencils
Niji waterbrush, Medium

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