Sources for More Information
Bulletin #15: Tree Risk Assessment — Recognizing & Preventing Hazard Trees
Some excellent publications are available from the International Society of Arboriculture that expand on the material presented in Bulletin No. 15.
Of special importance is: Tree Risk Assessment Manual, Second Edition by Julian A. Dunster.
Another helpful book, available from amazon.com and other book sellers:
A Photographic Guide to the Evaluation of Hazard Trees in Urban Areas by Nelda P. Matheny and James R. Clark
Probably no other single individual has done as much research and public education about understanding tree decay and hazards as the late Dr. Alex Shigo, former chief scientist and project leader with the U.S. Forest Service. His various publications and other materials are now available online. Of particular interest here is his leaflet, Tree Hazards–13 Questions That Could Save a Life. For more information visit Shigo Publications online.
Tree Risk Assessment Courses
Arborists and urban foresters now have the opportunity to expand their knowledge and training in the fundamentals of tree risk assessment by attending qualification courses offered in a number of locations. More information is available from the International Society of Arboriculture.