The bark protects the tree from attacking insect as it contains certain substances that repel them. The barks also prevent fungi from growing on the tree and draining it of nutrition. The bark protects the trees from decay during heavy rains.

During summer, loss of water through evaporation is prevented. In winter too the tree is safeguarded from the extreme cold.

The bark of the trees have been useful to man in different ways. In the early days man used it as firewood. Later he came to realize the medicinal value of certain barks. For example, the drug quinine used for the cure of malaria is obtained the cinchona tree.

In India cinchona trees are cultivated in the district of Darjeeling and in the Nilgiri hills. Cough medicines are also mad from certain barks. The cinnamon which we use in cooking is the bark of the cinnamon tree.