Media Lab 2
The changing colors of plant and tree leaves mainly rely on the seasonal changes of the environment. Basically, sunshine is required in the process of plant production however, this is only abundant during summer. During autumn, daylight gradually reduces until winter at the same time, signifies this period with their changing leaf color. This natural occurrence is mainly the response of the tree towards the seasonal change wherein it prepares itself to store its produced foods during the abundant periods of summer for its survival period in the winter. As the normal presence of chlorophyll in the leaves during summer is unnecessary during autumn and winter due to lack of daylight, the plant and trees reduces the said pigmentation for energy conservation. As an effect, the green pigmentation in the leaves decrease thus, allowing the presence of other color in its surface to become noticeable. These colors are commonly yellow, brown, orange, and others of which are all already present in the leaves yet are only overshadowed by the bright green pigmentation of chlorophyll. The noticeable effect of this occurrence is the changing color in the leaves during the said seasonal periods.
On other tree families, other colors such as bright red and purple become a dominant trait. The reason behind this change is basically the same however, glucose molecules are left on the leaves which further sunlight exposure and high humidity in the environment transform these molecules into bright red thus, leading to the color change of the leaf. In general, the changing color of the plants and trees are mainly their response and energy conservation reactions as preparation for their survival through the winter periods whereas the basic component of their food production process namely sunlight is scarce.
Science Made Simple (2005). Autumn Leaf Color: Why Do Leaves Change Color in the Fall? Science Made Simple, Inc. http://www.sciencemadesimple.com/leaves.html. May 30, 2008.