When the bark of a tree is removed in a circular fashion near its base, it damages the phloem, which is responsible for transporting sugars and other nutrients produced by photosynthesis in the leaves down to the roots for energy and growth. This process is called translocation. With the phloem damaged, the roots are starved of the energy they need for essential functions such as absorption of water and minerals from the soil, leading to their gradual drying up and eventual death.