Debarking a tree will kill it, provided the removal is complete around the trunk’s circumference. This complete removal of the bark and the tissues immediately beneath it is a process known as girdling. Girdling severs the tree’s internal transport system, removing the protective outer layers. The tree does not die immediately, but the damage sets in motion a lethal chain of events that leads to its eventual death.
The Critical Function of Bark Layers
The bark of a tree is far more than just a protective exterior; it houses the living layers responsible for transporting nutrients. Just beneath the rough outer bark is the inner bark, which contains the phloem. The phloem’s primary function is to transport sugars, produced during photosynthesis in the leaves, down to the rest of the tree, including the root system.
The vascular cambium is a thin layer of actively dividing cells situated directly beneath the phloem. This layer is responsible for the tree’s outward growth, creating new phloem cells toward the outside and new xylem cells toward the inside. The xylem, or wood, is located deeper inside the trunk and transports water and minerals up from the roots to the leaves. A bark injury that cuts through the phloem and cambium severs the critical pathway for moving food throughout the tree.
Girdling: The Mechanism of Tree Death
Tree death from complete debarking is caused by starvation of the roots, not a lack of water. When the phloem is completely removed in a ring around the trunk, the flow of photosynthetic products—the sugars—from the leaves to the roots is entirely interrupted. Since the phloem is an outer layer, the deeper xylem tissue often remains intact, allowing water and minerals to continue moving upward to the canopy for a time.
Deprived of the sugars necessary for energy and growth, the root system slowly begins to die. The roots use up their stored carbohydrate reserves, but they cannot receive new supplies from the leaves because the transport system has been severed above them. This root death can take months or even years, depending on the tree species and its existing energy reserves. Once the roots can no longer function, they fail to absorb water and nutrients, leading to the eventual collapse and death of the entire tree.
Survival and Severity of Damage
The survival of a tree after being debarked depends heavily on the extent and depth of the wound. If the girdling is only partial, meaning the wound does not encircle the entire trunk, the tree has a chance to survive. A healthy tree will attempt to compartmentalize the injury and grow specialized callus tissue from the wound’s edges to bridge the gap.
Callus formation is a regenerative process where new cambium, phloem, and xylem cells are created to close the wound and restore the severed vascular connection. Young, vigorous trees are generally more successful at closing small wounds quickly than older trees. However, if the damage is too wide or the tree is not growing actively, the callus tissue may never fully bridge the gap, leaving the tree vulnerable to decay and eventual death.
Accidental debarking is often caused by lawnmowers or string trimmers striking the trunk, which can cause partial girdling, especially on younger trees. Animals like beavers, voles, or deer rubbing their antlers can also cause significant bark damage. The best chance for the tree’s survival is to maintain its health by providing proper water and care, as vigorous growth accelerates the wound closure process.