Tree Risk Assessment Flashcards
6 cards from real Certified Arborist Test practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Tree Risk Assessment flashcards as text
In the ISA Tree Risk Assessment Qualification (TRAQ) framework, what are the three components of tree risk?
Answer: Probability of failure, target occupancy, and consequence of failure
ISA's TRAQ framework defines risk as the combination of three components: the probability that a part will fail, the likelihood that it will strike a target (target occupancy), and the severity of the consequences if it does (consequence of failure).
What is a 'target' in tree risk assessment terminology, and how does target occupancy affect overall risk rating?
Answer: People, property, or other valued objects that could be struck if a tree part fails
In TRAQ, a target is any person, property, or structure that could be struck by a failing tree part. Target occupancy — how frequently and for how long the target is present in the impact zone — directly scales the likelihood component of risk, since failure causes harm only when something is present to be struck.
What is 'trunk flare inspection' and what does its absence or deformity potentially indicate?
Answer: Examination of the base of the trunk to detect buried root flare, girdling roots, or basal decay that indicates structural or root system problems
Trunk flare inspection examines the tree base for the natural widening where trunk transitions to roots. Absence of visible flare (buried or compressed) can indicate deep planting, fill soil, girdling roots, or basal decay — all potentially serious structural or health issues.
What does 'failure mode' refer to in tree risk assessment, and what are the primary structural failure modes assessed?
Answer: The mechanism by which a tree or tree part fails — including stem failure, branch failure, root failure, and whole tree failure
Failure mode describes how a tree or part fails mechanically — the primary modes are branch failure, stem failure, root failure (overturning), and whole tree failure. Each mode has different defect indicators, risk assessment methods, and mitigation strategies.
What is the purpose of resistance drilling in tree risk assessment and what does the instrument measure?
Answer: It measures the drilling resistance of a small probe as it penetrates the wood, creating a profile that reveals density variations indicating decay, cracks, or voids
Resistance drilling (e.g., IML Resistograph) inserts a thin needle into the wood and continuously records the torque required to drill through successive layers — healthy dense wood produces high resistance, while decayed wood, voids, and cracks produce characteristic low-resistance profiles.
What is the minimum training requirement for an arborist to perform a Level 2 Tree Risk Assessment under ISA TRAQ standards?
Answer: Completion of the ISA TRAQ training and passing the associated written examination, with ongoing ISA certification maintenance
ISA TRAQ (Tree Risk Assessment Qualification) requires completing an ISA-approved TRAQ training course and passing the written examination. Maintaining TRAQ qualification also requires maintaining ISA Certified Arborist credentials and earning continuing education units.