Leaf after Death: Explore the benefits of tree ‘litter’

By Jason Ryndock

Chartreuse budburst tinged with pink is a welcome sight in spring after a dreary winter. Deep green leaves radiant in the summer sun are appreciated for their cool shade. Autumn foliage painted in vivid colors can stop traffic with its beauty. But what impression is left on the leaves that have fallen to the ground, besides the tread of your boots?

As autumn fades to winter, leaves begin their tumbling journeys from the canopy to the forest floor, constituting an immeasurable deluge of detritus (it is estimated that a single mature oak has 200,000 to half a million leaves…feel free to do the math!). They join a hodgepodge of leaves, twigs, bark, needles, seeds, and everything else in the forest subject to gravity. Though born of disorder and decay, the muted earth tones, varied shapes, and subtle textures of this miscellany can provide one of the most interesting perspectives of the forest. It therefore seems a bit undeserved that we refer to it as “litter.”

Don’t let this misleading term fool you. The last thing we’d want is for someone to report this to the ‘litter police’. The leaf litter layer is a critical component of forest ecosystems. Leaf litter is a shield that intercepts and absorbs raindrop energy, preventing the compaction and erosion of the soil. It’s a sponge that soaks up precipitation and a reservoir that holds it over time. It’s a seal too, that stops water from evaporating on dry or windy days. It’s insulation from temperature extremes: a frost guard and blanket in the winter and a cool canopy in the summer. It’s a source of food, shelter, hibernacula, and nesting material for a myriad of creatures. And it’s a recycling center, where carbon, nitrogen, phosphorous, and other important nutrients are returned to the soil so that they may once again find themselves in the makeup of a leaf.

Each year, approximately two tons of debris falls on every acre of deciduous forest. How are we not drowning in tree litter? You can thank the countless hungry mouths (and plasma membranes) of the litter community, in particular the bacteria and fungi. About 90% of litter decomposition is accomplished by these two kingdoms alone. Detritus, bacteria, and fungi form the basis of a diverse association of litter invertebrates, which in turn feed many vertebrates, including salamanders, shrews, and thrushes.

You can restore this important cycle to your own backyard. Next autumn, rather than kicking your leaves to the curb, put them on your gardens. Perhaps money doesn’t grow on trees, but mulch certainly does!