sometimes may even be appropriate for use as course trees depending on a variety of factors. A level 3 assess- ment can answer questions like: Is the pathogen or pest still present? Have the nutrient levels of the soil returned to normal? Is the tree producing new sound wood, or is the spread of decay outpacing the growth of new tissue? The recommendation for a level 3 as- sessment typically emerges from a level 2 assessment. To determine whether you should follow through on a recom- mendation, consider whether the tree in question is a course tree or could im- pact the course in the event of a failure, and what the possible consequence of a failure could be. While a level 3 assessment can be ex- pensive, it can reduce costs—monetary and environmental—in the long-term. Jumping to conclusions based on a level 1 or 2 assessment that provided insuf- ficient data might lead an operator to move a course element unnecessarily, or cut down a structurally stable tree, or remove a tree that’s health, disease, or insect problems could have been resolved with simple cultural manage- ment. In some cases, unneeded tree re- moval could result in further problems, like leaving the remaining trees more vulnerable to wind and weather events, increasing the risk of other failures. Thus, it is important to make forest management decisions using factual, science-based information. There aren’t many arborists with the experience, knowledge, and equipment capable of this level of inspection, and only a high- ly qualified consulting arborist should perform level 3 work. A NOTE ON RISK ASSESSMENT An arborist may recommend a formal risk assessment after a level 3 or even a level 2 assessment. (Sometimes an arborist can take good measurements without advanced equipment or knows enough information based on the spe- cies of tree and decay present to make a recommendation for risk assessment without proceeding to a level 3.) What? To determine the overall risk level of a tree, your arborist will consider: what the defect is; what kind
Co-author Katherine Taylor conducting a level 2 assessment on a tree at Mt. Herman, Calif. She’s collecting data using visual inspection and basic tools to produce an effective evaluation of the tree’s health and stability.
– Conduct a level 2 assessment of all course trees from the ground and platform. • Arborist weather event inspections: – Conduct a level 1 assessment of all course and surrounding course trees after major weather events. • Arborist assessment prior to de - sign and construction of a course: – Conduct a level 1 inspection of all trees within range of the new course location. – Conduct a level 2 inspection on all potential attachment trees. – Conduct a level 3 assessment on course trees based on the out- come of the level 2 inspection to confirm structural stability, provide data for the engineering and build teams, and fulfill any permitting requirements. • Arborist new or developing condi - tions assessment: – Have a consulting arborist conduct a level 2 assessment on trees that your staff or a commercial arborist have identified as a concern. – Have a consulting arborist perform level 3 testing of trees based on the outcomes of the level 2 assessment. • Arborist tree risk assessments: – Conduct risk assessments on trees within range of a course when the operator or staff have a concern or the arborist has identified signifi - cant defects. The health of your trees is vital to the sustainability of your business and the safety of your staff and guests. Fre - quent inspection—at the right level— will help protect your business, people, and forest for the future.
of failure could occur as a result of the defect; how likely the failure is to occur over a given timeframe; what the tree or tree part would hit if it did fail (a nearby platform, a zip line, people using the course, a building, etc.); how often that target is there (people, cars, and animals all move); and what the consequences to the target would be if the tree or tree part hit it. This information is put into a matrix that determines the risk level. At which point, your arborist will make management recommendations to reduce risk, which may include: cutting the tree down; pruning the part that might fail; making the tree a snag; monitoring the tree for some condition, like lean; or even moving the target—perhaps a bench or picnic tables—to another location. INSPECTION PLANNING How should you incorporate tree as- sessments on your site into your man- agement operations? How much time should you spend on your trees? Here are some recommendations to help you decide what kind of assessments (and therefore what kind of specialist) you might need: • Staff course inspections: – Conduct regular level 1 assessment with appropriately trained in-house staff to identify immediate man - agement needs and when to call an arborist for help between regular inspections. • Annual or bi-annual inspections by a qualified arborist: – Conduct a level 1 assessment on trees within range of the course.
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