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Outdoors: 'Leaves That Are Green'

Fall leaves
Dan Istitene
Getty Images
Leaves of all colors play important ecological roles.

Time hurries on
And the leaves that are green turn to brown
And they wither in the wind
And they crumble in your hand

Simon & Garfunkel were deceptively cheerful when they sang about lost love and the passage of time with Paul's ballad "Leaves That Are Green."

But if we are considering ecological systems, the lyrics "that's all there is" aren't true of the leaves which fall into a stream.

In late autumn, every withered brown leaf that drifts into the water acts as an infusion of nutrients into the complex stream ecosystem.

As soon as a leaf hits the water, food is leached from the tissues and quickly is colonized by fungi and bacteria which, in turn, provide carbohydrates and proteins for aquatic insects.

Leaf-eating aquatic insects, sometimes referred to as “shredders,” include caddisfly and crane fly larvae, mayfly nymphs and herbaceous stoneflies. Anglers will recognize these insects as the prey of fish.

The energy from last summer’s sunshine eventually passes into the food for the fish and other aquatic creatures, simply because in fall, leaves fall.

And though a dead leaf might whither in your hand, once time hurries on, it becomes the base of the food web for our inland streams and lakes.

"Outdoors with Coggin Heeringa" can be heard every Wednesday on Classical IPR.