Leave it to Leaves

Walking through the forest, we are surrounded by leaves. There are leaves on trees, leaves on bushes, plant leaves, and even leaves littering the ground. Leaves are amazing; there are many critically important roles that they play in ecosystem health.

A close up picture of a Madrone leaf

Of course, the first thing that everyone knows about leaves is that they create food for plants through photosynthesis. This is a process that we learn about in elementary school. Plants take in carbon dioxide and sunlight and through their leaves, add water from the roots and produce carbohydrates and oxygen. “It would be impossible to overestimate the importance of photosynthesis in the maintenance of life on Earth. If photosynthesis ceased, there would soon be little food or other organic matter on Earth. Most organisms would disappear, and in time Earth’s atmosphere would become nearly devoid of gaseous oxygen.”

Nearly all of the food in the world comes from leaves in one way or another. Root vegetables can’t develop without leaves. Animals eat the leaves of plants or the roots, fruits, or seeds of plants. Predators and prey alike are thus reliant on leaves for food.

Leaves also help to regulate the temperature of plants. On the underside of leaves are stoma—little mouth like openings—that enable the leaves to take in the carbon dioxide that plants need and release the oxygen that plants do not need. The stoma is also used to transpire water vapor. When temperature conditions warrant it, plants release stored water. In the summer, this released water vapor is used to cool the plant.

Leaves store water for the plant. It is the stored water that keeps the leaves spread and standing. When the water is needed elsewhere, plants pull water from their leaves to concentrate it in more structurally durable parts of the plant such as trunks, stems, and roots. When you see leaves that are curled or drooping, you are seeing leaves that have had the stored water pulled from them.

Storing water is not the only water-related role that leaves play. Leaves are also water catchers and directors. Leaves catch water and slow its descent to keep the plants roots from being damaged by the force of the water hitting the soil and to manage the amount of water getting to the roots, so that too much water does not arrive all at once. Leaves also direct the caught rainfall so that the water arrives at the roots best suited to take the water into the plant. When you examine a leaf, you see that it is designed with channels that collect and direct the water that falls on the leaf.

Fallen leaves are also important to healthy ecosystems. They provide habitat for other creatures. Insects, lizards, turtles, birds, and frogs are among the wild creatures that rely on fallen leaves for habitat. These fallen leaves serve as a blanket that protects the creatures from the elements keeping them warm and dry until spring comes again. Birds, squirrels, and other animals use the fallen leaves for nesting material. The fallen leaves also provide camouflage for many creatures, allowing them to hide from predators.

As the fallen leaves decompose, they are incorporated into the soil, replenishing nutrients and improving soil health. When the organic matter of fallen leaves decomposes into the soil, it improves airflow and water retention. The soil is healthier and thus grows healthier plants which grow the leaves that feed the plants, produce the oxygen, and do so much more.

Leaves are amazing. We should value them for the critically important things that they do to create healthy ecosystems. 

– Katha Miller-Winder, Education Committee