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
What is 'dynamic loading' and why is it more relevant to tree structural failure than static loading?
Answer: Dynamic loading involves fluctuating forces (wind gusts, impact) that generate higher peak stresses than the average static weight of the tree
Dynamic loading from wind gusts, oscillating movement, and impact events produces peak stresses far exceeding the static weight of the tree — most structural tree failures occur under dynamic loading events, not simply from the constant static weight of the tree.
What is the 'two-year rule' (or 'two-week rule') commonly referenced in arboricultural risk management?
Answer: A recommendation to complete corrective action on high-risk trees within 2 weeks of assessment completion
The two-week (sometimes two-week to two-month) recommendation is an informal arboricultural guideline suggesting that corrective actions identified for high-risk trees should be implemented promptly after assessment — reflecting the urgency appropriate to findings that indicate imminent threat to safety.
What condition is indicated by 'basal flare wetwood' or 'slime flux' seeping from a wound or crack at the base of a tree?
Answer: Bacterial wetwood infection causing internal pressure that forces foul-smelling, discolored sap through cracks or wounds
Slime flux (wetwood) is caused by anaerobic bacteria colonizing internal wood and fermenting the sap under pressure, forcing foul-smelling, discolored flux out through wounds, branch crotches, or cracks. While alarming in appearance, it often does not indicate structural failure but does indicate internal wood chemistry changes and moisture.
What does the presence of conks (bracket fungi) or mushrooms at the base of a tree indicate, and how does species identification affect the risk assessment?
Answer: Conks indicate active wood decay by the fruiting body's parent fungus, and species identification reveals decay pattern, rate, and extent of likely structural compromise
Conks and mushrooms at the base or trunk indicate active wood decay fungi. Species identification is critical because different decay fungi produce white rot versus brown rot, decay heartwood versus sapwood, and differ greatly in how rapidly and extensively they compromise structural integrity.
What is a 'no-go condition' in arboricultural operations, and provide an example of when a certified arborist must decline to perform tree work?
Answer: A site or tree condition where proceeding with work creates unacceptable risk to workers or the public, requiring refusal or delay until conditions change
A no-go condition exists when site or tree conditions create unacceptable worker or public risk — for example, trees near energized power lines without proper clearance, severely compromised trees with imminent failure risk while workers are in the canopy, or hazardous weather conditions. Arborists must decline work until conditions can be made safe.
What is the purpose of a tree risk assessment report, and what minimum elements should it contain according to ISA standards?
Answer: A formal document communicating risk findings to the tree owner — should include tree description, defects found, failure mode, risk rating, recommended actions, and reassessment interval
An ISA-compliant risk assessment report must document the tree and site description, defects found, failure mode assessed, risk rating (using the TRAQ matrix), specific recommended actions, and the recommended reassessment interval — providing a clear, legally defensible communication of findings and guidance.