A man needs trees to survive because without them there will be no oxygen and we will die suffocating. A man relies on a tree for food, shelter and oxygen. Even the underground water which we drink is purified because of the trees. There are varieties of trees and each tree has their own value, but when they are grown together they form a forest. Forest helps in maintaining the proper rainfall.
Everything in the ecosystem is connected and so is the man and tress. The man needs oxygen to live and releases carbon dioxide, in the similar way trees need carbon dioxide to live and releases oxygen. Furthermore, with wood from trees we can make comfortable furniture, keep our-self warm in winter by making a nice fireplace and make a house. In exchange for this, it is the duty of a man to water the plants and plant more seeds so that we never run out of trees.
As the humanity is evolving, we are cutting down more and more trees to establish cities. We are forgetting that if there are no tree, there will be no trace of human left on the earth. It is important for each one of us to protect trees because if we cut trees at this ratio, soon trees will extinct and man will become endangered species.