Removing a tree’s bark can certainly kill it, though the outcome depends entirely on the extent and location of the damage. Bark serves as the protective outer covering, but its removal exposes and destroys layers responsible for transporting nutrients and facilitating growth. This damage, whether caused by animals, machinery, or natural events, disrupts the tree’s fundamental life-support systems. When the inner, living tissues are compromised, the tree’s ability to sustain itself is immediately threatened. The tree’s survival hinges on which layers are damaged and how much of the trunk’s circumference is affected.
The Essential Layers: Why Bark Removal Is Critical
Beneath the rough, protective outer bark lie distinct layers indispensable for the tree’s survival. The outermost of these living tissues is the phloem, which functions as the primary nutrient transport system. The phloem moves sugars and carbohydrates produced during photosynthesis downward to the trunk, branches, and roots for fuel and storage. This relatively thin layer is easily destroyed when the outer bark is scraped away.
Just beneath the phloem is the vascular cambium, a single layer of actively dividing cells. The cambium is responsible for all lateral growth, producing new wood (xylem) toward the inside and new phloem toward the outside. This growth layer is the source of all new vascular tissue that keeps the tree alive. Removing the bark inherently removes both the phloem and the vascular cambium, which are physically inseparable from the bark.
The destruction of these layers effectively cuts the supply line for both food and future growth. Without the phloem, the roots are starved of the necessary sugars to grow and function. Without the cambium, the tree cannot produce the new tissues needed to seal off the wound or increase its girth. Any damage that penetrates beyond the outer bark and into these layers poses a significant threat to the tree’s health.
Girdling: The Fatal Mechanism of Circumferential Removal
The most definitive way that bark removal kills a tree is through a process known as girdling, or ring-barking. Girdling occurs when a band of bark, including the phloem and cambium, is removed completely around the circumference of the trunk or a major branch. This action severs the entire phloem pipeline, creating an impassable barrier to nutrient flow.
Sugars produced in the crown can no longer travel down the trunk to reach the roots below the wound. The roots, unable to access the necessary carbohydrates, slowly begin to starve. While the leaves and upper trunk may appear healthy because water transport, which occurs in the inner xylem, remains intact, the tree is already doomed.
The root system will eventually exhaust its stored energy reserves, a process that can take a year or more, especially in large trees. Once the roots die, they can no longer absorb water and minerals from the soil. This failure ultimately leads to the death of the entire tree, resulting in a standing but dead trunk. For girdling to be fatal, the removed band must be wide enough, typically a few inches, to prevent the cambium from bridging the gap and reconnecting the phloem.
Tree Response to Localized Damage and Survival Factors
When bark removal is only partial, or localized, the tree attempts to survive the injury by sealing off the damaged area. Trees cannot truly “heal” by regenerating lost tissue; instead, they employ a defense strategy known as Compartmentalization of Decay in Trees (CODIT). This process involves the tree creating chemical and physical barriers to wall off wounded tissues and prevent the spread of decay.
The tree forms a protective boundary known as the barrier zone, which chemically alters the wood surrounding the wound to make it resistant to fungi and bacteria. Simultaneously, the vascular cambium at the edges of the wound begins to produce specialized tissue called callus wood. This callus grows over the exposed area, working to seal the wound.
Several factors determine if a tree survives localized bark damage. The width of the wound is paramount; if the damage covers more than 50% of the trunk’s circumference, survival odds decrease significantly because the remaining phloem may not adequately supply the roots. The depth of the injury also matters; wounds that reach the sapwood (xylem) are more serious than those that only remove the phloem, as they interfere with water transport.
The tree species and the time of year when the injury occurred also influence the outcome. Some species are naturally better at compartmentalization than others. Damage occurring late in the growing season, after the tree has stored energy, is generally less damaging than injuries sustained in the spring. A smaller, healthier tree with a localized wound has a strong chance of survival, provided it can successfully produce the callus tissue necessary to seal the breach before decay sets in.