ISA Tree Risk Assessment 3

Question 1

In the ISA Tree Risk Assessment Qualification (TRAQ) methodology, what are the three components used to determine the overall risk rating?

Accepted Answer

Likelihood of failure, likelihood of impacting a target, and consequences of failure

Answer

Tree species, age, and location

Answer

Trunk diameter, lean angle, and crown density

Answer

Root depth, soil type, and wind exposure

Question 2

What does 'target zone' mean in tree risk assessment?

Accepted Answer

The area within striking distance of the tree or its parts where people, property, or activities could be impacted by a failure

Answer

The area where herbicide should be applied around the tree

Answer

The area where the tree's roots extend underground

Answer

The specific location where a tree should be planted

Question 3

Which of the following is considered a 'Level 2' assessment in the TRAQ system?

Accepted Answer

A basic assessment involving a detailed visual inspection of the tree from the ground, walking 360 degrees around it

Answer

A limited visual assessment from a distance during a walk-by survey

Answer

An advanced assessment using tools such as resistance drilling, sonic tomography, or aerial inspection

Answer

A desktop review of the tree's maintenance history and species characteristics

Question 4

What structural defect is indicated when a tree develops a pronounced 'bulge' or swelling on one side of the trunk at the base?

Accepted Answer

A potential response growth indicating internal decay or structural stress on the opposite side of the bulge

Answer

A graft union from nursery propagation

Answer

Normal buttress root flare development

Answer

A site where the tree was previously cabled

Question 5

When assessing a tree with codominant stems, what visual feature indicates the highest probability of failure at the union?

Accepted Answer

A visible crack or seam at the union combined with included bark between the stems

Answer

Bark ridges pushed upward at the union forming a visible collar

Answer

Lichen growth covering the union area

Answer

Both stems being exactly the same diameter

Question 6

What is 'occupancy rate' in tree risk assessment and how does it affect the risk rating?

Accepted Answer

A measure of how frequently people or moveable property are present within the tree's target zone, directly affecting the likelihood of a failure impacting a target

Answer

The percentage of the tree's crown that is alive and has foliage

Answer

The ratio of trees to open space in the assessment area

Answer

The number of birds or animals nesting in the tree