KNOW YOUR
ARBORIST QUALIFICATIONS
The TRAQ methodology for risk assessment is subjective and uses accepted international methods for risk assessment approved by the International Standards Organization (ISO). The TRAQ method uses two matrices—a likelihood of failure matrix and a risk rating matrix—to determine the level of risk for a particular tree. The method aims to safely preserve trees, so it is important that the risk assessor is experienced and knowledgeable enough to suggest arboricultural treatments or other actions that can be used to mitigate tree risk and bring a tree back from dangerous to acceptable levels.
ASSESSMENTS
At minimum, your arborist should have an International Society of Arboriculture (ISA) arborist certification and the Tree Risk Assessment Qualification (TRAQ). More advanced arborists may also have an ISA Board Certified Master Arborist certification and an American Society of Consulting
ally also use a form (an ISA basic tree risk assessment form or equivalent) to record information about the tree(s) they are assessing. The form serves as a record for the operator of the arborist’s observations and measurements, but is not intended to be submitted to munici- palities or in a formal report as the only source of tree risk assessment data. Level 2 assessments require adequate time—at least 15-30 minutes per tree— and thus adequate budget. This level of inspection produces an effective evalua - tion of the health and structural stability of trees, and it will inform whether a risk assessment or level 3 assessment is needed. When? This is the standard assessment an arborist would conduct when called out to examine a tree based on a con- cern or observation you have made. Lev- el 2 assessments should be conducted on each course tree or potential course tree before design and construction, and every year as a part of normal manage- ment. Your arborist may also recom- mend a level 2 as a result of findings from a level 1 inspection they conducted on trees within range of the course. LEVEL 3 When the situation demands a higher level of information regarding tree stability or health, a level 3 assessment is called for. Level 3 assessments can be time consuming and require special equipment, training, and experience. Thorough assessments of this type are often required for high value trees or trees that are critical components of a course or facility. What? A level 3 assessment provides details about the structural stability of a tree, any decays, pathogens, insects, pests, or nutrient deficiencies present, and possible issues with the soil that require management. Depending on the tree and the goal of the inspection, a level 3 assessment can include: • Aerial inspection for evaluation of structural defects in the upper parts of trees.
Arborists (ASCA) Registered Consulting Arborist (RCA) certification.
• Detailed target analysis, which may include research into the use of the site and the condition of some of the target structures. • Decay testing, including increment boring, drilling with a small diam- eter drill bit or micro resistance recording drill, single path sonic assessment, sonic tomography, electrical impedance tomography, and microscopic analysis for fungal species identification. • Health evaluation, including tree ring analysis, shoot length measurement, detailed health and vigor analysis, and starch level assessment. • Soil or tissue testing in cases where a nutrient deficiency or a pathogen is suspected. • Root inspection and evaluation, including root and root collar exca- vations, root decay evaluations, and ground penetrating radar. • Storm and wind load analysis, including a detailed assessment of the tree’s exposure and protection factors, computer-based estimations according to engineering models, and wind reaction monitoring over a defined interval. • Measuring, monitoring and assessing a change in trunk lean. The TRAQ is intended to increase an arborist’s level of competence in assessing tree risk. TRAQ has been in place for six years. It is not a license to assess trees for risk, rather it is a syllabus that describes the assessment method and current arboricultural understanding and practices.
• Load testing using methods such as a hand pull test, a measured static pull test (aka standard integrated assess- ment), or measured tree dynamics. When? An operator might seek a level 3 assessment when regulatory scrutiny is a factor. For example, during a level 3 inspection, an arborist could test sup- port trees at the base and, if needed, at critical elevations using sonic tomogra- phy to provide the course owner with data about tree species characteristics like wood strength and tree health. This data is vital for engineers running numbers. It also allows building-code officials to be more certain that the trees are sound and stable. Level 3 testing can also be used to monitor how a condition is progressing. Trees with decay columns can remain structurally stable for a long time and As part of a level 3 assessment, co-author Scott Baker uses a mi- cro-resistance drill to look at the tree’s growth rate and determine if there is any decay.
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