ISA Tree Risk & Management 3 — Questions and Answers
Question 1: Which structural defect is characterized by a union where bark is trapped between two stems, reducing wood-to-wood contact?
- Codominant stems
- Included bark (Correct answer)
- Reaction wood
- Watersprouts
Correct answer: Included bark
Included bark occurs when bark is embedded in a branch union, creating a weak attachment that is prone to splitting.
Question 2: What is the primary purpose of a 'static load test' on a tree?
- Measure sap flow rate
- Apply controlled force to assess structural response and root plate movement (Correct answer)
- Determine soil pH under the canopy
- Identify fungal species causing decay
Correct answer: Apply controlled force to assess structural response and root plate movement
A static load test uses a measured pulling force to evaluate how a tree and its root system respond to mechanical stress.
Question 3: Lion-tailing (removing inner foliage and branches) increases tree risk because it:
- Reduces photosynthesis and tree health
- Concentrates weight at branch tips, increasing end-weight leverage (Correct answer)
- Creates large pruning wounds prone to decay
- Removes epicormic shoots that stabilize the crown
Correct answer: Concentrates weight at branch tips, increasing end-weight leverage
Lion-tailing shifts foliage to branch ends, creating heavy end-loading that dramatically increases the lever arm stress on branch attachments.
Question 4: A 'branch collar' should be preserved during pruning primarily because it:
- Contains the vascular cambium needed to form callus and compartmentalize decay (Correct answer)
- Provides nutrients directly to the removed branch
- Is where sap pressure is highest
- Marks the natural target for insect attack
Correct answer: Contains the vascular cambium needed to form callus and compartmentalize decay
The branch collar contains specialized tissues that produce callus wood and chemical barriers to compartmentalize and limit decay after pruning.
Question 5: Which of the following fungi is most associated with white rot, breaking down both lignin and cellulose?
- Armillaria mellea
- Ganoderma applanatum (Correct answer)
- Inonotus obliquus
- Laetiporus sulphureus
Correct answer: Ganoderma applanatum
Ganoderma applanatum (artist's conk) is a classic white rot fungus that degrades both lignin and cellulose, leaving pale, fibrous wood.
Question 6: When is a 'limited visual assessment' the appropriate level of tree risk assessment?
- When a tree is suspected to have advanced internal decay
- For routine, walk-by evaluations of many trees in a low-consequence setting (Correct answer)
- After a tree has caused property damage
- When an advanced tool like a resistograph is unavailable
Correct answer: For routine, walk-by evaluations of many trees in a low-consequence setting
A limited visual assessment is a walk-by inspection appropriate for inventorying many trees where consequences of failure are low and defects are not obvious.
Question 7: Which of the following root defects poses the GREATEST immediate structural risk to a tree?
- Minor surface root damage from lawn mowing
- Circling roots girdling the main trunk at grade (Correct answer)
- Shallow root system in sandy soil
- Roots growing toward a sidewalk
Correct answer: Circling roots girdling the main trunk at grade
Girdling roots constrict vascular flow and mechanically weaken the root flare, significantly reducing anchorage and tree stability.
ISA Tree Risk & Management 3
Which structural defect is characterized by a union where bark is trapped between two stems, reducing wood-to-wood contact?