The more you know about trees, the easier and more economical it will be for you to keep your trees healthy. Here are two key things to remember about the root system of most trees:
- The root system usually extends out well beyond the tree’s branch tips.
- The root systems are primarily confined to the top 12 inches of soil — especially in heavy clay soils. This is because the roots must have oxygen from the air.
Tree Injuries and Decay
The trunk, branches, and roots of a healthy tree grow in diameter from the outside outward. But when a tree is injured, decay-causing organisms (usually fungi) can gain access to the inside of the tree and damage its strength and health. The tree’s internal defenses — some pre-existing and others created in response to an injury — slow down the spread of decay while the tree adds strength by gowing outward. The decay may be covered over by new growth on the outside, compensating somewhat fo rthe loss of strength, but the decay remains. Tree wounds do not heal.
Some or all of the wood present at the time of a serious injury may rot. As decay advances, the center of the tree may become hollow, making it weaker and more susceptible to further damage. But wood produced after the injury is protected from decay by a barrier zone, created by the tree in response to the injury. This barrier zone is very resistant to decay, although it can be damaged by later injuries to the tree.