Deciduous trees dropping their leaves in the fall is a natural phenomenon that comes with numerous benefits. As the days become shorter and there is less sunlight for photosynthesis, trees no longer require their leaves. However, it is interesting to note that leaf-dropping trees and plants are not responding to the loss of sunlight but to the increasing hours of darkness as the nights grow longer. This process, known as abscission, causes the leaves to turn yellow, gold, copper, or orange, and a layer develops between the leaf and the twig, cutting off water and nutrients. In essence, the leaves are not simply falling; the trees are actively pushing them off.
The shedding of leaves allows trees to channel their energy into root and structure growth and strength. Additionally, without leaves, trees can retain more water and nutrients in these areas during the colder months. Another advantage of leaves dropping is that snow and rain could potentially damage the leaves if they remained on the tree. Without leaves, winter’s cold air and wind can pass through the branches more easily, minimizing the risk of fungal diseases associated with wet weather. On sunny days, the absence of leaves allows sunlight and warmth to reach the ground under the tree.
Interestingly, homeowners who have deciduous trees shading and cooling their homes and yards in summer can also appreciate the extra light and warmth that they receive in winter after the trees shed their leaves.
But what should we do with those fallen leaves? One option is to leave them on the ground and let nature take its course. Fallen leaves provide a free organic mulch that is superior to store-bought options made of bark from non-local trees. These leaves are compatible with the local ecosystem as they originate in the area. They provide a haven for bugs and microorganisms, including beneficial spiders, gnats, overwintering butterflies and caterpillars, worms, moths, and bumblebees. These creatures play a vital role in the ecosystem, and it is important to tolerate them. Additionally, leaving the leaves on your lawn can provide a natural cover and nutrient layer, protecting it during the colder and wetter months. Mowing the fallen leaves into the lawn will reduce the leaf volume and prevent moisture buildup, which could harm a dormant lawn.
However, it is important to note that some trees, plants, bushes, and hedges drop an excessive amount of leaves that may suffocate other plants underneath. Fallen leaves can also harbor fungi or bacteria, which could promote disease if they are left near the roots or in contact with the trunks of other plants. In such cases, it is advisable to move the leaves away from the trunk by hand, rake, or broom. These leaves can then be added to a compost pile or the city’s brown compost bins, ensuring that this valuable natural resource is properly utilized.
The article also highlights the experience of the author, who has a ray wood ash tree in their backyard that drops a significant amount of leaves in the fall. They spread these leaves in their vineyard to enrich the soil.
For those interested in observing this phenomenon, the author recommends visiting the Las Flores Learning Gardens at the Las Flores Community Center in North Napa, where leaves blanket the low-water and native gardens until they are cleaned up. The abundance of leaves requires additional compost bins to handle the volume.
In conclusion, instead of raking and disposing of autumn leaves, it is worth considering the benefits of leaving them in place or properly using them as organic mulch. Not only can they enhance the beauty of your garden, but they also provide a winter habitat for important species and nourish the very plants that dropped them, ensuring a vibrant burst of life in the coming spring.
