Wednesday, November 12, 2014
Fall Foliage... the parting gift
The Caddo Maples are the last to begin foliage change their process usually foretells the first freeze will occur within a week. They are unusual in that all of their leaves do not freeze-fall; much of their glorious foliage, although crisp, remains tree-bound until Spring. Just as their color change predicts a coming freeze, these last leaves foretell the arrival of Spring as they are literally tossed from the tree when it is expected to arrive. As the Maples had predicted last week, our first deep freeze roared in early Wednesday morning and suddenly Winter is upon us… in a most vengeful manner.
Trees lose their leaves to give additional sunlight for warmth during the cold winter months and Nature has provided us with a stunning visual as a parting gift. Although the following explanation will be a vast over simplification, it may provide insight into the foliage change. During the spring and summer the trees use their leaves to collect air and water to turn it into food. The process, called photosynthesis means ‘putting together with light’ so as the days shorten and daylight diminishes, the gathering process ends. The leaf is no longer necessary to the tree and begins its transformation providing breathtaking color for a brief moment in time.
The chemicals chlorophyll and carotenoids are present in the leaf cells throughout the growing season with chlorophyll making leaves the bright green color. As daylight decreases in autumn, chlorophyll production stops and the chlorophyll disappears. With the loss of chlorophyll the carotids, which have been there all along, become visible and display lovely yellow leaf color. Lastly the anthocyanins arrive and take center stage, ushering in the vibrant reds we associate with Autumn.
Anthocyanins, which are glucose, are singularly responsible for the brilliant hues of purple, crimson, and scarlet. They are a fickle lot, insisting on warm sunny days and crisp evenings to slow the closing of the leaf veins and trap excess sugar produced at this time… if the weather does not comply to their demand, lackluster reds are produced.
Shade and the foliage show are not all the leaves have to offer… their parting gift is perhaps the most important. As the leaves drift from the trees and collect below they continue to work by slowly decomposing. Over time this process adds nutrients to create a dark rich soil which nourishes the fledgling the saplings as they grow to become forest giants like their parents. Nature is always at work, regardless of the season.