Hazard Tree Management in Alaska










Tree that fell on a building
Large hardwood cankerConks on the base of a tree


Insects, diseases, decays, and other forms of tree defect and mortality are important parts of a healthy, functioning forest ecosystem. They play many ecological roles in forests such as altering plant succession and providing wildlife habitat. In forest settings, trees die and fall to the ground where they become recycled. Although dying and falling trees are important in the development of forests, they are not welcome in high use recreation areas where they risk human life and property.

People enjoy recreating in forests, particularly forests with large old trees. These are the very trees that often provide the greatest risk in terms of hazard. Large trees are more likely to contain significant amounts of internal wood decay and other defects. Also, they can cause more damage when they fall. Thus, recreation managers are often faced with an apparent paradox -- how to maintain safety for visitors while providing an aesthetic environment with large trees.

The goal of hazard tree management is to sustain the forest in an aesthetically pleasing condition and at the same time eliminating unacceptable risk to visitors. A hazard tree program can be part of the solution of meeting this challenge. Simply identifying and treating hazard trees is a short-term solution to the problem, however. Careful and wise vegetation management is the long-term key to sustaining a healthy forest condition that will produce a minimum of hazard trees in the future.

This webpage was designed to provide managers with basic information about hazard trees. We present the information with a logical flow from hazard tree theory to recognition, evaluation, and lastly prevention. If the topic of hazard trees is generally new to you, we suggest starting at the top of the index and reading the sections in the order presented. Numerous links are also provided to allow the user to browse specific topics of interest.

What is hazard?

Hazard is the exposure to the possibility of loss or harm. With regard to trees, it is the potential that a tree or part of a tree will fail and cause injury or damage property. All standing trees of sufficient size, alive or dead, present some hazard. All trees will eventually come down. But high potential for tree failure by itself does not automatically mean a tree is hazardous. Hazard exists when a tree is within striking distance of an object of any value.

Thus, a tree is considered potentially hazardous if:

  • it has defects which predispose all or part of the tree to failure, and
  • it is located so that the failure poses a threat to people or property.

Tree on Roof Jeep Smashed by a large tree