Tree risk assessment is a hot topic among arboriculturists, urban foresters, and land managers responsible for trees. It is necessary to demonstrate that reasonable care has been taken in the management of trees to provide an adequate defense in the event of damage caused by the felling of trees. The most used and misused risk assessment method is the ISA method developed by Matheny and Clark (199), which evaluates the risk of falling trees in three components: potential for failure, size of the part, and objective rating. The potential for tree failure is the first component of tree risk assessment.
This involves considering the mechanical integrity of the tree and the likelihood that it or part of it will fail within a given period. This system makes it possible to comparatively classify the risk of failure in a population of trees, but it has little value when evaluating the risk of a solitary tree because there is nothing to make a comparison with. The second component is an environment conducive to falling trees. This includes factors such as soil type, wind speed, and other environmental conditions that can increase the risk of tree failure. It is important to consider these factors when assessing the risk of falling trees. The third component is an objective rating.
This involves assigning a numerical value to each component of tree risk assessment to determine the overall risk level. The numerical values are based on factors such as tree species, age, size, and condition. The higher the numerical value, the higher the risk level. Tree risk assessment is an important tool for land managers responsible for trees. It helps them identify potential risks and take appropriate action to reduce or eliminate them.
By assessing the risk of falling trees, land managers can ensure that their trees are safe and that they are taking reasonable steps to protect their property.