Rabbits are a common winter pest, often targeting young trees and shrubs when other food sources become scarce. They strip the bark from woody plants, especially favoring the thinner, smoother bark of younger specimens. This damage, often occurring near the base of the trunk or above the snow line, can severely compromise a tree’s health or lead to its death. Recovery depends entirely on the extent of the damage.
Understanding Girdling: The Critical Damage Point
The specific type of damage rabbits inflict is known as girdling, which involves removing a ring of bark around the circumference of the trunk. This action is devastating because the tree’s structure for transporting nutrients is located just beneath the outer bark. The inner bark, or phloem, is responsible for moving sugars produced during photosynthesis from the canopy down to the roots for growth and storage.
Directly beneath the phloem is the vascular cambium, a thin layer of cells that produces both new phloem and new xylem wood. When rabbits remove these two layers entirely, they effectively sever the internal connection between the roots and the leaves. This disruption prevents the downward flow of sugars, leading to a slow starvation of the root system. While the upward movement of water and minerals through the inner wood (xylem) may continue, the roots eventually die without the necessary energy supply.
Assessing Tree Survival Based on Damage Severity
The likelihood of a tree recovering hinges on the percentage of the trunk’s circumference that has been stripped of bark. If the damage covers 100% of the trunk’s diameter, cutting off the entire phloem layer, the tree is considered completely girdled and will not survive long-term. Although the tree may leaf out normally in the spring using stored energy reserves, it will die as those reserves are depleted and the roots starve.
A tree has a good chance of recovery if the damage is only partial, leaving 50% or more of the circumference intact. The tree attempts to heal itself by forming wound wood, or callus, which grows inward from the edges of the remaining bark to cover the exposed wood. If the damage is less than half of the circumference, the callus tissue will eventually bridge the gap, restoring the nutrient flow. For completely girdled trees, a technique called bridge grafting can be attempted on high-value specimens, which involves connecting the bark above and below the wound with live wood scions to create an artificial pathway for nutrient transport.
Immediate Steps to Encourage Recovery
For trees with partial damage, the first step is to clean up the wound to promote smooth callus formation. Carefully use a sharp knife to trim away any loose or ragged edges of the remaining bark, shaping the wound into a smooth oval or football shape. This practice encourages the tree to seal the wound more efficiently. Do not apply traditional wound dressings or tree paint, as these products can trap moisture and delay the natural healing process.
Protecting the exposed area from drying out and preventing further damage is important for encouraging recovery. Wrapping the trunk with a simple material like hardware cloth or burlap can shield the inner wood from weather and pests while the callus is forming. Ensuring the tree receives adequate water throughout the growing season provides the resources necessary for wound healing. Avoid applying high-nitrogen fertilizers, which promote canopy growth that the damaged transport system may not be able to support.
Effective Strategies for Future Protection
Proactive protection is the most reliable way to prevent rabbits from inflicting damage on vulnerable trees. The most effective method is the use of physical barriers, such as tree guards or fencing made of hardware cloth or chicken wire. These enclosures must be secured around the trunk, ensuring the material is rigid enough that rabbits cannot push against it to reach the bark.
For adequate protection, the barrier should stand at least 24 to 30 inches tall to account for snow accumulation, which allows rabbits to reach higher parts of the trunk. It is important to secure the base of the guard firmly against the ground or bury it a few inches deep to stop rabbits from burrowing underneath. While commercial repellents are available, they rely on taste or smell to deter feeding and often require frequent reapplication, making them less dependable than a sturdy physical barrier.