Storm damage and injury from deer, cattle, horses and lawnmowers contribute to bark injury by tearing at the tree trunk. When a bark injury has occurred, the exposed sapwood or heartwood is more susceptible to attack by fungi that initiates the decay process. Insects and animals such as raccoons, woodpeckers and squirrels that inhabit tree cavities utilize the tree wound as their front door. Carpenter ants, in particular, will excavate tunnels throughout the tree and excrete wood preserving enzymes as they do so. While these preservatives are beneficial to the tree, the tunnels the ants create allow water to accumulate.
Excess water can result in wood rot.
In the past, tree cavities were simply filled with cement in an effort to block up the wound. Today, we know that the cement does not allow the tree to bend and therefore renders the tree more susceptible to storm damage. Because cement does not bond with wood, the gap created between the tree and cement collects water. This dark and moist environment allows fungi to proliferate. When a tree is wounded, it uses its natural defense of compartmentalization to create a barrier between the wound and the rest of the tree.