Why do trees change color in autumn?
How do trees change colour
On the basis of autimn defoliation trees and plants can be divided into two groups. The first includes those plants and trees which undergo defoliation every year and are called deciduous trees while the other includes the evergreen plants or trees which defoliate very slowly and remain green throughout the year. Evergreen plants also undergo defoliation but at one time only a small portion oftheir leaves fall off. Every year with the approch of autumn the trees begin to have their period of rest.
In autumn the leaves fall and eventually rot down to give the leaf-mould and humus which are essential to support rich vegetation. During this period gradually their leaves turn yellow and curl up and fall on the ground. The tree then remains almost completly inactive untill the arrival of spring. The denuded or defoliated trees or plants are a sad sight but at the same time very useful to plants because after it plants get a new life and look. Before defoliation the leaves take yellowish brownish and reddish hues. Plants are living organisms which need food to survive. This food os obtained by utilizing the organic substances provided by the leaves. Just like anmals plants also produce waste materials and have to get rid of them, but they do it in a differeny way. They have to retain waste materials in their tissues until autumn. When the time comes for trees to shed their leaves the plants extract all the useful products from them, and shake off the wast material behind. Due to the presence of these waste materials the leaves turn yellow. Brown and red. When the leaves are shed a layer of dry needles is left on the tree and it is visible in winter.