The Leaves of Autumn

As we move into Fall and Winter, we start to notice things about our environment that are much different from Summer. Days seem duller and less vibrant, and nature starts to lose its color. One thing that contributes to this dullness is the leaves changing as Fall comes around. The leaves changing is due to a process called senescence, which is the final stage of a leaf’s development, shown by the breakdown of its components.

Step-by-step Process:

1. As shorter days are introduced when daylight hours decrease during the fall, trees slow their food production process (photosynthesis)
2. This causes chlorophyll to break down, which makes the green pigment that gives the leaves their color no longer replenished. The breakdown of chlorophyll causes the pigment to fade, which in turn makes the leaves lose their color.
3. New pigments fill in their place and become visible
   • Pigments called carotenoids, which produce yellow and orange, already start within the leaf as the colors change. They are hidden underneath the large amounts of chlorophyll, and once the chlorophyll is gone, these colors begin to show
   • Some trees also create new pigments called anthocyanins when sugars trapped within the leaves are influenced by bright light. These produce vibrant colors like red and purple.
   • Some factors that influence the color that is produced are the temperature and the moisture of the environment. Typically, an ideal temperature calls for cool nights and sunny days to produce the most vibrant colors. A fall with more moisture, which means large amounts of rain, helps create more vibrant colors, while a drought can cause the leaves to drop before they even get to change. 
4. The trees take back nutrients from the leaves before they fall, storing them in the branches for when Spring rolls around
5. The leaves fall as a protective layer is formed around the base, eventually closing off the veins completely. The leaves then detach and fall to the ground. This process is called Abscission.

The process serves great importance because it allows the trees to maintain nutrients and store energy during winter for Spring and Summer when the leaves are most vibrant. Without this process, we wouldn’t be able to see the full potential of Summer or the cold blissfulness of Winter.