Peeling bark off a tree can kill it, depending on the extent of the damage. The bark is more than a protective outer layer; it is a multi-layered system responsible for transporting the tree’s food supply and enabling growth. Damage that compromises this system, especially around the entire circumference of the trunk, puts the tree on a path toward demise.
The Critical Function of Tree Bark
The bark is the tree’s first line of defense, but the living tissues beneath it form the true life support system. Just inside the outer bark is the phloem, or inner bark, which carries sugars and nutrients throughout the tree. These sugars, produced during photosynthesis, are transported downward to feed the trunk, branches, and roots.
The vascular cambium is a thin layer of actively dividing cells situated between the phloem and the wood. This layer is responsible for the tree’s increase in girth, producing new phloem cells outward and new xylem cells inward. Damage to the cambium directly halts the production of new transport and structural cells.
Beneath the cambium is the xylem, or sapwood, which transports water and dissolved minerals upward from the roots to the leaves. The phloem transports food down while the xylem transports water up, forming two distinct circulatory systems necessary for the tree’s survival.
Understanding Girdling and Fatal Damage
Bark removal kills a tree through a process called girdling, which occurs when a complete ring of bark, phloem, and cambium is removed around the entire trunk. This effectively severs the phloem highway, preventing the downward flow of sugars from the leaves to the roots. The crown may look healthy initially because the xylem is often left intact and continues to transport water upward.
The roots are cut off from their food source and begin to starve, gradually depleting stored energy reserves. This root starvation can take months or even years, depending on the tree species and its stored carbohydrates. Once the roots can no longer sustain themselves, they die, and the entire tree perishes.
Partial bark removal or scrapes that do not completely encircle the trunk are usually not fatal because the phloem and cambium remain connected. A tree can often survive if less than 50% of the trunk’s circumference is damaged, provided the remaining intact tissue sustains the roots. The width of the removed ring is also a factor, as a wide girdle makes it nearly impossible for the cambium to bridge the gap.
Tree Recovery and Managing Damage
Trees do not “heal” by regenerating damaged tissue; instead, they employ a strategy known as Compartmentalization of Decay in Trees (CODIT). This involves the tree creating physical and chemical barriers, or “walls,” in the wood to isolate the injured area. The tree walls off the damaged section to prevent the spread of decay into healthy wood.
For minor bark damage, a tree’s defense mechanisms are often sufficient to seal the wound. The cambium around the wound begins to grow over the exposed wood, a process called callusing, which slowly closes the opening. If the damage is extensive, the most helpful action is to clean up any ragged edges of the remaining bark with a sharp tool to allow the tree to form a smooth callus margin.
Applying wound paints or dressings is not recommended, as these products can trap moisture and promote the growth of decay-causing organisms. The best practice is to allow the tree’s natural compartmentalization process to take effect and monitor the wound for signs of infestation or disease. The tree’s long-term prognosis depends on its species, age, overall health, and its ability to rapidly form protective barriers.