Tree
Plants and trees are an inseparable part of our lives and there would be no life on Earth without them. Air on our planet would not be breathable but for trees and plants because they take in carbon dioxide from the air and let out oxygen. Besides this, the fertile upper layers of soil are held in place, against blowing wind and flowing water, by tree and plant roots. This prevent land from becoming infertile and turning into an arid desert. Forests of all types and varieties cover over 35 million sq km of our planet. Small seeds grow into plants and then gradually into bigger trees. Trees perform all the functions like a plant but on a much larger scale. Growth takes place mainly at the ends of trees i.e. the branches grow further in length by branching out and the roots move deeper and deeper. In this process of growth, the relatively older roots and branches become thicker for supporting new branchouts, while the trunk of the tree also grows thicker.
Trunks grow from within and a cross-section of a tree’s trunk would show rings of light and dark coloured wood. One dark and one light coloured ring signifies a year of growth, that is why the age of a tree can be calculated by counting the number of rings inside its trunk. As the trunk grows, it forms a rough scaly surface on the outside called a ‘bark’. Young trees have smoother barks, but as trees grow older the bark becomes scaly, cracks and eventually falls off. New bark is in the meanwhile being generated from within. A tree’s bark prevents the inner wood from losing water and drying out and protects the tree from fungus and moulds. Since wood from trees can be put to a very large number of uses, constant cutting down of trees has led to deforestation all over the world and the world’s forest reserves have reduced substantially. Conservationists are today planting fast growing species of trees in order to restore the forest resources.
