Why Does a Tree Lose Its Bark?

Bark loss might seem like a minor, superficial wound, but it can kill your tree. Underneath the bark is the tree's phloem layer. It carries nutrients between the leaves and the roots. If it becomes too damaged, the tree dies. The bark also protects the tree from insects and diseases. Unfortunately, if the bark is too severely damaged, almost nothing will help the tree except for a bridge graft, which is difficult to accomplish.

Bark is an important food source in the fall, winter and spring for animals like mice, voles, rabbits and deer. Trees are more at risk in the winter when other food sources are gone or buried under snow cover. You can tell which animal caused the damage by where the damage is located on the trunk. Voles cause damage near the base of the tree. Rabbit damage is usually 12 to 24 inches from the ground. Deer damage will be several feet from the ground.

A number of environmental factors can wreak havoc on a tree. Fluctuating temperatures in the winter causes tree to expand and contract, which may result in the bark peeling off the tree. Bark that is dried, cracked, sunken or missing on the south or southwest side of a tree is usually caused by sun scald. On sunny winter days, the bark heats up and cambial activity becomes stimulated. When the sun goes down, the bark temperature drops too fast and kills the tissue. Environmental stress like drought can also cause a tree to lose its bark, according to horticulturist Ron Smith with the North Dakota State University Extension Service.

Trees may have their bark damaged or stripped by lawn mowers and weed eaters. Limbs damaged from winter's snow and ice build-up may strip bark from the tree when they fall or are removed. In the fall and winter, deer can create 3-foot-long strips of shredded or peeled bark by rubbing their antlers against the trunk. Another less common possibility is a lightning strike. Although symptoms can vary, it can cause bark to loosen and hang off in strips.

Disease can cause a tree to lose its bark. Cankers are fungal diseases that kill or damage the bark on a tree. They often occur in trees that have been injured or wounded. Superficial cankers form only in the bark and don't cause the bark to fall off. Cambial cankers, which are more severe, will cause the bark to slough off and expose the cambium layer. Bark loss around woodpecker holes is also a common sign on trees with Dutch elm disease.