CTSP Risk Assessment 3 — Questions and Answers
Question 1: A risk assessment matrix typically combines which two primary factors to determine overall risk rating?
- Tree age and species
- Likelihood of failure and consequences of failure (Correct answer)
- Tree height and canopy spread
- Inspection frequency and maintenance cost
Correct answer: Likelihood of failure and consequences of failure
The ISA risk matrix crosses likelihood of failure with consequences of failure to produce an overall risk rating.
Question 2: Which of the following is an example of a dynamic load that increases tree risk?
- Soil compaction
- High wind gusts (Correct answer)
- Root girdling
- Fungal conks on the root flare
Correct answer: High wind gusts
High wind gusts are a dynamic, time-varying force that dramatically increase the risk of tree failure.
Question 3: What does 'occupancy rate' refer to in tree risk assessment?
- The percentage of bark covered by moss
- How frequently the target zone is occupied by people or vehicles (Correct answer)
- The density of the tree canopy
- The number of co-dominant stems present
Correct answer: How frequently the target zone is occupied by people or vehicles
Occupancy rate describes how often a target (person, vehicle, structure) is present in the impact zone.
Question 4: A CTSP observes a mushroom fruiting body (conk) at the base of an elm tree. What is the most appropriate interpretation?
- The tree is recovering from drought stress
- It indicates active root or butt rot, raising structural concern (Correct answer)
- The conk is cosmetic and poses no risk
- The tree is producing beneficial mycorrhizae
Correct answer: It indicates active root or butt rot, raising structural concern
Conks at the base indicate active decay fungi breaking down root or butt wood, which can seriously compromise stability.
Question 5: In the ANSI A300 risk management framework, which action is most appropriate for a tree rated as 'extreme' risk?
- Schedule routine inspection in 12 months
- Apply preventive fertilization
- Take immediate mitigating action (removal or pruning) (Correct answer)
- Install a lightning protection system
Correct answer: Take immediate mitigating action (removal or pruning)
Extreme risk trees require immediate action—typically removal or significant corrective pruning—to eliminate the hazard.
Question 6: Which tree defect is most difficult to detect during a standard Level 1 (walkby) visual assessment?
- Large dead limbs in the upper canopy
- Internal decay not visible at the surface (Correct answer)
- Significant lean away from vertical
- Obvious crown dieback
Correct answer: Internal decay not visible at the surface
Internal decay produces no external symptoms until advanced stages, making it nearly invisible during a basic visual inspection.
Question 7: A property owner asks a CTSP to assess a tree growing next to a school's main entrance. How does target occupancy affect the risk rating?
- It has no effect on risk rating
- High occupancy raises the consequences of failure, increasing overall risk (Correct answer)
- High occupancy decreases risk because the tree is monitored more closely
- Target occupancy only matters for residential properties
Correct answer: High occupancy raises the consequences of failure, increasing overall risk
High occupancy increases the likelihood that failure will harm someone, elevating the consequences and overall risk rating.
CTSP Risk Assessment 3
A risk assessment matrix typically combines which two primary factors to determine overall risk rating?