The bark of a tree serves an important purpose in the life of a tree. It is the outer covering and protects it from the elements in much the same way as skin does for humans and animals. Many people are surprised to learn that when they remove the bark they are doing irreparable harm to the tree and may even kill the tree or stunt its growth.
The main purpose of bark on a tree is to protect the inner layer of phloem. This layer is essential to the life of a tree because it is its main source of energy. The leaves and roots produce the food that the tree needs and the phloem carries it to the rest of the tree dispersing it as it is needed for life and growth.
Even if you don't fully remove a piece of bark from a tree, just scratching it can damage the phloem layer. If this damage is confined to less than of the distance around the tree, or even up to half of the distance, it will survive, but damage over that amount is detrimental to its survival. Even small amounts of damage to the bark can result in the death of some of the leaves and branches.
Each species of tree has a different type of bark and each one has distinguishing characteristics. The bark of the White Birch, for example, is white and almost like paper. In fact you can actually write on the bark of this tree. While it is an outer covering for the phloem layer, in the white birch the bark also serves another purpose. With its light coloring it is able to reflect the heat of the sun and keep it from damaging the inner core of the tree.
The bark of the Eucalyptus tree serves a very unique purpose. The inner side of the bark is very oily. If there is a fire, the oil on the bark will burn and this protects the rest of the tree so that it will not burn. This unique characteristic allows forests of Eucalyptus trees to rejuvenate themselves because the basic structure of the tree has not been harmed by the burning.
Trees are beneficial to the environment, both in their aesthetic value and the benefit for the air. By stripping the trees of bark, you are pronouncing their death sentence and leaving them to die an untimely death. At certain times, some species of trees do shed their bark, but this is part of the natural growing process in order to develop a thicker outer covering to provide more protection.
Why don't you take the time to examine the trees in your community to have a look at the bark? Areas of damage can be corrected and this will let you enjoy the beauty that only trees can provide for a lot longer.