Discoloration and decay are processes initiated by wounding and involve the injured tree, microorganisms, and the environment. Any wound or break that exposes wood causes a defensive reaction in the tree and provides an opportunity for infection by microorganisms. Trees resist the spread of injury and infection through the process of compartmentalization. The details of compartmentalization vary among tree species. In all wounded trees, effective compartmentalization leads to relatively little loss of function and small amounts of discolored and decaying wood.
Broken branches are the most common form of storm-related injury.
Branches that are broken high in the tree crown are not likely to initiate discoloration and decay in the main stem. Discoloration that does spread into the bole from broken branches will tend to be in the central core of the tree, the least valuable portion for products. Extensive branch breakage in the outer crown can result in a significant loss of foliage and reduced growth. Split forks occur when one member of a twin or multiple stem is pulled and broken away from the remaining stem. Split forks can result in large wounds and extensive loss of foliage.