With the changing leaves providing a breathtaking show, it certainly feels like fall this week. Everything about this season is a feast for the senses, all the more poignant because it is fleeting, lasting only a few short weeks. As the leaves complete their color change they begin to fall, thrown from their parents branches to delicately swirl to the ground in drifting patterns. Then they accumulate in colorful heaps and become a joy to dance or walk through with their crackle and swish, hiding the occasional snap of a twig or acorn beneath them. But the miraculous leaves are not yet finished; they will complete their life cycle after falling by decomposing, thus adding valuable nutrients to the forest floor.
Trees have an internal clock that alerts them to the fact that winter is coming as the days become shorter and the sunlight is diminished. Knowing it is time to prepare for the winter, they toss their leafy offspring rather than continue to support them. It is time for the tree to live off the food that was stored within it when the light from the sun was bright and the rainfall sufficient for a process called photosynthesis to occur. Photosynthesis, which means “putting together with light”, is the process wherein the tree takes water from the ground through roots, carbon dioxide from the air, adds some sunlight and mixes it all together during the summer months to create glucose…food for the growth of the tree. As the leaves are shed and the branches become bare, the tree is able to support itself by absorbing the diminished water and light of winter while living off the food stored during the summer.
The leaves change to their traditional fall colors just as the tree has decided to shed them with the season change. Chlorophyll, which aids in the production of the glucose, is what makes the leaves green. As the tree prepares for winter, the chlorophyll slowly fades and the lovely colors emerge; many of the colors have been there all along but were masked by the green. Be sure to take a walk or drive to catch this momentary gift… the memory of it will carry us through the coming days and nights of barren winter.
Note: The ‘science’ explanations are vastly oversimplified...