According to New Mexico State University, removing a complete band of tree bark from a tree can kill the tree because it contains the phloem layer that is responsible for carrying food to the roots. When the tree has no way to receive food, the roots will eventually die and stop sending water and other nutrients to the leaves.
The bark of a tree is made up of cork and phloem. This outer layer protects an inner layer of cambium and xylem. The phloem is considered living tissue in a tree, and the xylem is what is most commonly known as the tree’s wood. The cambium is the moist layer that is very thin, and it is the regenerative layer that creates the xylem and phloem.
The process of removing the phloem in a circle completely around the tree is referred to as girding. Removing a circle that is less than a fourth of the circumference around the tree will cause harm to the tree and its growth, but it will not completely kill the tree. If the circle around the tree is half of the circumference of the tree or greater, there is a higher chance that the tree will die from the damage.