CATS Urban Tree Risk Assessment & Mitigation 2 — Questions and Answers
Question 1: Which root defect is most commonly associated with trees planted too deeply in urban settings?
- Circling roots (Correct answer)
- Tap root decay
- Root plate failure
- Adventitious root growth
Correct answer: Circling roots
Circling or girdling roots frequently develop when trees are planted too deeply or confined in pots, restricting vascular flow and structural stability.
Question 2: When applying the ISA tree risk assessment matrix, a 'Likelihood of Failure' rated as 'Probable' combined with 'Consequences of Failure' rated as 'Significant' produces what overall risk rating?
- Low
- Moderate
- High (Correct answer)
- Extreme
Correct answer: High
The ISA matrix places Probable likelihood × Significant consequences in the High risk category.
Question 3: Which tool is most appropriate for detecting internal decay in a standing urban tree without causing additional wounding?
- Increment borer
- Resistograph (Correct answer)
- Shigometer
- Mallet and sounding
Correct answer: Resistograph
The Resistograph uses a fine drill to measure resistance and detect voids or decay with minimal wounding compared to increment borers.
Question 4: A mature cottonwood overhangs a busy pedestrian walkway in Albuquerque. The primary target category that drives risk rating in this scenario is:
- Property value
- Occupancy rate of the target (Correct answer)
- Species longevity
- Aesthetic condition
Correct answer: Occupancy rate of the target
Target occupancy—how frequently people or property occupy the impact zone—is the key factor in determining consequence severity.
Question 5: What mitigation action best reduces the likelihood of failure for a co-dominant stem union with included bark?
- Crown cleaning
- Structural cabling (Correct answer)
- Crown raising
- Fertilization
Correct answer: Structural cabling
Structural cabling limits the independent movement of co-dominant stems, reducing stress at the weak union with included bark.
Question 6: Under the ISA BMP for risk assessment, a 'Basic Assessment' is most appropriate when:
- Significant structural defects are observed
- A routine visual observation is needed from ground level (Correct answer)
- Advanced equipment like tomography is required
- Legal liability is a primary concern
Correct answer: A routine visual observation is needed from ground level
A Basic Assessment involves a visual, ground-level inspection without specialized equipment and is used for routine tree evaluations.
Question 7: Sapwood staining in an Albuquerque ash tree is most likely an early indicator of:
- Bacterial wetwood
- Verticillium wilt (Correct answer)
- Hypoxylon canker
- Armillaria root rot
Correct answer: Verticillium wilt
Verticillium wilt causes characteristic vascular staining visible in cross-sections of sapwood, common in ash and other hosts in the Southwest.
CATS Urban Tree Risk Assessment & Mitigation 2
Which root defect is most commonly associated with trees planted too deeply in urban settings?