Removing the bark from a tree can result in its death, but the outcome depends entirely on the extent and depth of the damage. Bark is not simply a tough outer skin; it is the tree’s primary defense and a complex vascular system responsible for distributing life-sustaining nutrients. When this protective layer is breached, the tree’s internal circulation is exposed and often severed, leading to a cascade of events that can starve the entire organism. The tree’s survival hinges on whether the injury is shallow and localized or if it completely interrupts the pathways that connect the leaves to the roots.
The Critical Role of Tree Bark
The bark is composed of several layers, each performing a specialized task necessary for the tree’s continued life and growth. The outermost layer is the rough, corky exterior that acts as a shield, protecting the delicate inner tissues from physical injury, temperature fluctuations, and invading insects or pathogens. This tough shield is the tree’s first line of defense.
Immediately beneath the outer bark lies the phloem, sometimes called the inner bark, which is the specialized circulatory tissue responsible for transporting energy. The phloem moves the sugars produced by photosynthesis in the leaves down to the trunk, branches, and roots. This downward flow of nutrients sustains the non-photosynthesizing parts of the tree, including the vast root system.
Just inside the phloem is the vascular cambium, a thin layer of actively dividing cells that drives the tree’s girth growth. The cambium creates new phloem cells toward the outside and new xylem cells toward the inside every year, allowing the tree to expand in diameter. If an injury penetrates and destroys this thin layer, the tree loses the ability to generate new conductive tissues in that area and to effectively seal the wound.
Girdling: The Fatal Injury
The complete removal of the bark layer around the entire circumference of the trunk or a branch is known as girdling, and this injury is almost always fatal to the tree. Girdling severs the phloem and the vascular cambium, creating an impassable gap in the tree’s internal communication and food-delivery system. Common causes of girdling include damage from lawnmowers or string trimmers, feeding by rodents or deer, and the improper placement of wires or ropes around the trunk.
The mechanism of death is not immediate, but rather a process of slow starvation for the roots. Sugars manufactured in the canopy can no longer travel past the girdled section to replenish the energy stores in the roots. Although the deeper xylem tissue, which transports water and minerals upward from the roots, often remains intact, the roots eventually run out of stored carbohydrates and die.
Once the roots die from starvation, they can no longer absorb water and nutrients, which then causes the canopy to slowly fail. The tree may continue to look healthy for weeks, months, or even years after the initial injury, depending on its size and species. This delay is due to the roots drawing on their stored energy reserves and the canopy’s continued ability to receive water, but the injury has set the tree on an irreversible path toward death.
Factors Influencing Survival
A tree’s ability to survive bark removal is directly related to the percentage of the trunk’s circumference that has been damaged. When the injury is limited to only a fraction of the total diameter, the tree has a strong chance of survival because the remaining intact phloem can still transport sufficient nutrients. As a general guideline, a tree is likely to survive if less than 50% of the circumference has been removed, provided the remaining bark is healthy.
The depth of the injury is also a major determinant, as the cambium layer must be protected for recovery to occur. If the damage only removes the outer bark and leaves the thin, living vascular cambium intact, the tree can often regenerate the lost tissues. However, if the wound penetrates deep into the sapwood, the tree’s overall health is severely compromised, and the risk of decay increases significantly.
Survival also depends on the tree’s overall vigor, species, and age. Younger, thin-barked species, such as fruit trees or birches, are far more susceptible to fatal girdling than mature trees with thick, deeply furrowed bark. A tree that is already stressed by drought, disease, or pests will have a significantly lower capacity to dedicate energy to wound repair.
Repair and Recovery
When a tree sustains a partial bark injury, it does not truly “heal” in the way human skin regenerates, but rather “seals” the damaged area through a process called compartmentalization. This process involves the tree creating chemical and physical barriers to wall off the injured tissues and prevent the spread of decay and infection into the healthy wood. The tree isolates the damage to protect its internal structure.
The physical sealing is achieved through the formation of callus tissue, often referred to as wound wood, which develops from the margins of the injury. This specialized tissue grows from the edges of the remaining healthy bark, slowly rolling over the exposed wood in an attempt to bridge the gap. A vigorous tree can eventually cover a small wound entirely with this new growth, sealing the injury from the environment.
To aid a tree with a partial bark wound, the best practice is to leave the area exposed and dry, avoiding the common mistake of applying wound dressings. Research shows that substances like tar, paint, or petroleum-based products can impede the natural compartmentalization process and trap moisture. Trapped moisture encourages the growth of decay-causing fungi, so focus instead on maintaining the tree’s overall health by ensuring proper watering and protection from further mechanical injury.