Trees benefit us in many ways. They can also cause major damage when limbs or the whole tree falls on power lines, cars, houses or people. Usually, weakened trees give some warning signs of danger. By learning to recognize the signs and to follow-up with prompt, proper action, you can often manage this risk, saving yourself grief as well as money.
What is a hazard tree?
A tree failure occurs when a tree or large part of a tree breaks and falls. Hazard Tree Management deals in probabilities of failure rather than certainties. Age, species (especially rooting and branching characteristics), site, and condition all influence the relative hazard of the tree. A high probability of failure does not make a tree a hazard; there also must be a target that could be damaged or injured if the tree fails.
Trees become a potential hazard when there is a target. A target is a structure, vehicle or a person that would be struck by a falling tree or its parts. A tree leaning over the bedroom is most hazardous. Trees near high use areas are more of a risk than those near infrequently visited areas, as the probability of a person being hit is greater. Priorities for removal or corrective treatments depend on the hazard rating of the tree.
What can you do?
Check your trees, especially large, old ones. Periodic, thorough inspections are essential to prevent accidents. At least one inspection per year should be made, but two per year are recommended, one in the summer while the leaves are on the tree and one in the winter. Every tree likely to have a problem should be inspected from bottom to top, looking for signs of root or butt rot and continuing up the trunk toward the crown, noting anything that might indicate a potential hazard.
A word about your liability. If you have a hazard tree, you may be responsible for any damage it causes if it falls. If a tree in your yard fails and damages your neighbor's property, and you have no prior knowledge of its condition as a hazard tree, your neighbor's general policy may cover the damages. This determination however, may be disputed. Documenting the condition of your trees can be important in case of litigation involving the failure of a tree.