The verdure vanishes

CHENNAI IS proudly called "City of Trees", but there has been a severe threat to that pride because a number of roadside trees have been gradually disappearing. Many of them are more than 100 years old. These trees, provide us with a massive green umbrella. Summer reminds us of their need to get relief from a scorching sun.

One of the reasons behind the destruction of trees is the unscientific digging operations carried out by various Government departments. During the process, the workers ruthlessly cut the lateral roots coming from the trunk of the tree. These roots run to several metres and at their end, have absorbing roots. When the lateral roots are severed, the tree cannot absorb water and its hold on the soil becomes weak.

More pathetic is the fact that after a digging operation, the surface is left open for several months and this damages the taproots.

Another major reason that is ignored is the depletion of subsoil water due to the increasing number of multi-storeyed buildings.

Avenue trees absorb and survive on ground water, as nobody waters them. With no rain and a depleting ground water level the trees are bound to starve.

Various kinds of pollution are also responsible for the vanishing green cover. The number of automobiles on the roads is increasing at an alarming rate. These vehicles emit carbon monoxide and other carbon particles which affect the foliage and result in premature withering of leaves.

These gases also keep the atmospheric temperature high which causes thermal damage to the trees.Besides, with so many buildings being constructed, sand particles get collected on the leaves. The leaves are the breathing parts and prepare food for the plant. When their surface is covered with soil or dust, it affects their photosynthetic efficiency. This weakens the tree over a period of time. Polluted water, stagnating around trees, destroys the roots. Polluted water carries acids, detergents and other effluents from houses and nearby industries.

Natural calamities such as heavy rain and cyclonic winds dislodge trees and break the branches. Even if part of a tree is broken, the tendency is to cut the entire tree and not allow it to regenerate. Branches of some trees such as Peltophorum, Samania saman, Kygelia pinnata, Thebubia rosea, and Moringa indica break during strong winds.

To protect trees from destruction, digging operations should b carefully done. The surface of the cut roots should be covered with coal tar or cement to prevent them from drying roots and infection.

At present, the survival of roadside trees depends on the availability of ground water. We can fix recharging pipe holes around the trees. The residents of that area or voluntary agencies or the Corporation authorities can pour water through these holes and allow water to percolate into the soil around the trees. Sometimes waste materials from industries, homes or construction materials get piled up around the tree surface, resulting in percolation of these unwanted materials into the soil.

Planting of trees, which are susceptible to breakage during storms should be avoided. Breaking of branches can be prevented by tying the lateral branches to the trunk of the tree with thick ropes during the monsoon.

Pruning techniques can be adopted to remove weak branches just before the monsoon to avoid damage to the entire tree.

When saplings are planted along new roads, they should be allowed to grow without producing any lateral branches up to a minimum height of six feet. This is done by careful removal of lateral buds as and when they are formed.

This results in development of lateral branches only above seven feet, which gives the umbrella-like look. It has been found that this practice doubles the life span of avenue trees.

Above all, the basic principle of co-existence can protect these trees.

O. M. MURALI & S. RAJARAJAN

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