It is not easy to kill a deep-rooted tree. It takes much time to kill it. A tree is too strong to be killed by a simple attack of a knife. It has grown slowly consuming the earth, feeding upon its crust, absorbing years of sunlight. The strength it has stored through a long period of hard work and patience, cannot be destroyed in one go.
When a tree is chopped, the barks bleed but soon they heal up and expand again to their former size. If one wants to kill a tree, it has to be pulled out of the anchoring earths. Its most sensitive part, i.e. the root, has to be exposed to the sun and air. Once it is done, the tree is killed.