Flashback Friday: Hazard Tree Inspections

Brent Botts’, Hazard Tree Inspections, article was originally printed in The Register, December 1991.

“Perhaps the most long-term commitment to the Appalachian Trail is maintenance. A very important part of any maintenance program is management of hazard trees. Hazard trees along the Appalachian Trail not only present a safety hazard but can result in trail and facility damage, as well as additional hours of labor in clearing fallen trees.

The objective in managing hazard trees is to provide for user safety, protect adjacent resources, preserve Trail investments, and provide user access and convenience. To meet these objectives, Trail maintainers should be able to assess hazard trees.

Just what is a hazard tree?

Trees spend their entire lives going up but will eventually fall. The questions for us are: Where will a tree fall, and, even more importantly, when will it fall? A tree within its height of a shelter would be considered hazardous long before it would be anywhere else along the Trail.

When a tree will fall is a more difficult question. If we knew the exact time a trees would fall, we would not consider it hazardous until that instant. Because of the many variables in the equations of what makes a tree fall, we are left with some generalizations. As trees lose vigor, they become more susceptible to falling. The other factor is the environment. Most trees will fall on a windy day or during a flood, heavy snow, or other unusual condition. With those qualifiers in mind, consider the following inspection procedure:

First, get a good idea of the main species of trees in the area you are surveying. Review the kinds of defects likely to be associated with that species. Second, note the general age and condition of the trees in the area your are inspecting. The chances for development of serious defects increase with the tree’s age.

Be systematic in the survey method. On individual trees, begin inspection at the top, and proceed downward, or at the butt and proceed up. Here is a quick list of what to look for:

Top
Dead tops that may become weakened by rot and break off.

Crown
Hanging, broken, or cracked branches that should be removed.
Signs of general decay, such as short, weak growth and dead branches scattered through the crown.
Evidence of split crotches, both in hardwoods and between the forks of forged conifers. Unless the split is very recent, it will be marked by lines of healing callus similar to those that form along frost cracks.
Evidence of dead cambium and associated sap rot on branches or trunks of hardwoods.

Trunk
Fungus conks, or the remains of old, weathered conks, indicate the presence of heart rots.
Evidence of rot and hollowness in the heartwood of hardwoods when large branches have been sawn or broken off.
Large, open wounds showing rot within.
Mistletoe swellings, with exposed dead wood, on trunks of fir.
Cankers on the main trunk deep enough to weaken it at the point where they occur.
Excessive flattening of the trunk from any cause.

Butt
Wounds, open and closed, from fire or mechanical injury and associated rots.
Conks, or remains of conks, indicating basal decay, including those from roots near tree bases.
Dead cambium
Reduced firmness of rooting from water or wind action.

That checklist does not mention every defect or indicator that might be encountered but includes most of the major ones. Be alert for anything that might have a bearing on safety.”

Editor’s Note, March 2017: ATC is working with land managing partners to develop a trail-wide hazardous tree management protocol, and recently offered hazardous tree training to clubs in each region. Your Trail club should regularly inspect areas of congregation (overnight sites, viewpoints, trailheads and parking areas) for any trees that display conditions listed above, or just ones that look like they are not thriving. Record your efforts and report any concerns to your local land managing agency and ATC Regional Office. Different land managers have different criteria for addressing hazardous trees. Remember that special certification is required for volunteer sawyers to fell trees on Trail lands. Sawyers are reminded not to saw above your level of training, and should feel empowered to walk away from any situation they deem unsafe.