Isa Arborist Tree Risk Assessment Exam
Questions And Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A |
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1. Which three components are commonly considered when
characterizing tree risk?
A. Species, age, and height
B. Defect, disease, and decay
C. Likelihood of failure, likelihood of impact, and consequences
D. Diameter, crown spread, and height
Answer: C. Likelihood of failure, likelihood of impact, and
consequences
Rationale: Tree risk assessment considers how likely a tree part is to
fail, how likely that failure is to affect a target, and what consequences
could result. These components allow the assessor to characterize risk
systematically rather than relying only on the presence of defects. A
large tree is not automatically high risk, and a tree with defects may
pose relatively little risk if failure is unlikely to affect a target.
2. What is the primary purpose of a tree risk assessment?
A. To identify every tree species on a property
B. To determine whether identified conditions create unacceptable risk
and guide appropriate management
C. To establish the monetary value of every tree
D. To determine the exact remaining lifespan of each tree
,Answer: B. To determine whether identified conditions create
unacceptable risk and guide appropriate management
Rationale: Tree risk assessment is intended to identify hazards,
evaluate the likelihood and consequences of potential failures, and
support reasonable management decisions. It is not designed to predict
an exact date of tree failure or determine precisely how many years a
tree has remaining. Risk assessment provides a structured basis for
deciding whether monitoring, mitigation, further investigation,
pruning, removal, or another action may be appropriate.
3. Which condition most directly describes a target in tree risk
assessment?
A. A location, person, property, or activity that could be affected by tree
failure
B. A fungal organism living on the tree
C. A pruning cut that has closed over
D. The tree's measured diameter
Answer: A. A location, person, property, or activity that could be
affected by tree failure
Rationale: A target is something that could be struck or otherwise
affected if a tree or tree part fails. Targets can include people, vehicles,
buildings, utility infrastructure, roads, sidewalks, recreational areas,
or other valuable property. Identifying targets is essential because a
tree defect by itself does not fully describe risk. The same defect may
present substantially different risk depending on what lies within the
potential impact area and how frequently the target is present.
4. Which factor generally increases the likelihood of impact?
,A. A target is rarely present in the potential impact area
B. A target is continuously occupied beneath the tree
C. The potential target is located outside the likely impact area
D. The site is inaccessible to people
Answer: B. A target is continuously occupied beneath the tree
Rationale: Likelihood of impact depends substantially on target
occupancy and exposure. If a target is continuously present within the
potential impact area, the opportunity for a failed tree part to strike
that target is greater than when the target is rarely present. Occupancy
is therefore an important consideration when assessing risk. A location
with intermittent or very low occupancy may have a different risk
profile from an area occupied throughout the day.
5. What is the most appropriate initial approach when beginning a
tree risk assessment?
A. Immediately recommend tree removal
B. Establish the assessment objectives, scope, and site conditions
C. Begin climbing the tree regardless of conditions
D. Remove all dead branches before inspecting the tree
Answer: B. Establish the assessment objectives, scope, and site
conditions
Rationale: A competent assessment begins by understanding why the
assessment is being performed, what trees and targets are within
scope, and what site conditions may affect the assessment. The
assessor should establish the inspection scope and consider access,
weather, hazards, available records, and relevant site information
before conducting detailed observations. This helps ensure that the
assessment is systematic and that important contextual information is
not overlooked.
, 6. Which statement best distinguishes a hazard from risk?
A. A hazard is always unacceptable, while risk is always acceptable
B. A hazard is a condition capable of causing harm, while risk
incorporates likelihood and consequences
C. A hazard refers only to insects, while risk refers only to fungi
D. A hazard and risk are identical terms
Answer: B. A hazard is a condition capable of causing harm, while
risk incorporates likelihood and consequences
Rationale: A hazardous tree condition may include structural defects,
decay, dead branches, root problems, or other conditions capable of
contributing to failure. Risk goes further by considering the likelihood
that failure will occur, the likelihood of impact with a target, and the
consequences of the resulting impact. Therefore, identifying a defect
does not by itself establish the magnitude of risk.
7. Why is the tree's surrounding environment important during risk
assessment?
A. Environmental conditions can influence tree stability, loading,
growth, and target exposure
B. The surrounding environment has no relationship to tree risk
C. Only soil color matters during assessment
D. Environmental conditions determine the tree's species
Answer: A. Environmental conditions can influence tree stability,
loading, growth, and target exposure
Rationale: Trees interact continuously with their surroundings.
Changes in wind exposure, soil conditions, construction, drainage,
neighboring trees, grade, irrigation, and land use can influence tree
stability and structural performance. Environmental conditions can
Questions And Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A |
Instant Download Pdf
1. Which three components are commonly considered when
characterizing tree risk?
A. Species, age, and height
B. Defect, disease, and decay
C. Likelihood of failure, likelihood of impact, and consequences
D. Diameter, crown spread, and height
Answer: C. Likelihood of failure, likelihood of impact, and
consequences
Rationale: Tree risk assessment considers how likely a tree part is to
fail, how likely that failure is to affect a target, and what consequences
could result. These components allow the assessor to characterize risk
systematically rather than relying only on the presence of defects. A
large tree is not automatically high risk, and a tree with defects may
pose relatively little risk if failure is unlikely to affect a target.
2. What is the primary purpose of a tree risk assessment?
A. To identify every tree species on a property
B. To determine whether identified conditions create unacceptable risk
and guide appropriate management
C. To establish the monetary value of every tree
D. To determine the exact remaining lifespan of each tree
,Answer: B. To determine whether identified conditions create
unacceptable risk and guide appropriate management
Rationale: Tree risk assessment is intended to identify hazards,
evaluate the likelihood and consequences of potential failures, and
support reasonable management decisions. It is not designed to predict
an exact date of tree failure or determine precisely how many years a
tree has remaining. Risk assessment provides a structured basis for
deciding whether monitoring, mitigation, further investigation,
pruning, removal, or another action may be appropriate.
3. Which condition most directly describes a target in tree risk
assessment?
A. A location, person, property, or activity that could be affected by tree
failure
B. A fungal organism living on the tree
C. A pruning cut that has closed over
D. The tree's measured diameter
Answer: A. A location, person, property, or activity that could be
affected by tree failure
Rationale: A target is something that could be struck or otherwise
affected if a tree or tree part fails. Targets can include people, vehicles,
buildings, utility infrastructure, roads, sidewalks, recreational areas,
or other valuable property. Identifying targets is essential because a
tree defect by itself does not fully describe risk. The same defect may
present substantially different risk depending on what lies within the
potential impact area and how frequently the target is present.
4. Which factor generally increases the likelihood of impact?
,A. A target is rarely present in the potential impact area
B. A target is continuously occupied beneath the tree
C. The potential target is located outside the likely impact area
D. The site is inaccessible to people
Answer: B. A target is continuously occupied beneath the tree
Rationale: Likelihood of impact depends substantially on target
occupancy and exposure. If a target is continuously present within the
potential impact area, the opportunity for a failed tree part to strike
that target is greater than when the target is rarely present. Occupancy
is therefore an important consideration when assessing risk. A location
with intermittent or very low occupancy may have a different risk
profile from an area occupied throughout the day.
5. What is the most appropriate initial approach when beginning a
tree risk assessment?
A. Immediately recommend tree removal
B. Establish the assessment objectives, scope, and site conditions
C. Begin climbing the tree regardless of conditions
D. Remove all dead branches before inspecting the tree
Answer: B. Establish the assessment objectives, scope, and site
conditions
Rationale: A competent assessment begins by understanding why the
assessment is being performed, what trees and targets are within
scope, and what site conditions may affect the assessment. The
assessor should establish the inspection scope and consider access,
weather, hazards, available records, and relevant site information
before conducting detailed observations. This helps ensure that the
assessment is systematic and that important contextual information is
not overlooked.
, 6. Which statement best distinguishes a hazard from risk?
A. A hazard is always unacceptable, while risk is always acceptable
B. A hazard is a condition capable of causing harm, while risk
incorporates likelihood and consequences
C. A hazard refers only to insects, while risk refers only to fungi
D. A hazard and risk are identical terms
Answer: B. A hazard is a condition capable of causing harm, while
risk incorporates likelihood and consequences
Rationale: A hazardous tree condition may include structural defects,
decay, dead branches, root problems, or other conditions capable of
contributing to failure. Risk goes further by considering the likelihood
that failure will occur, the likelihood of impact with a target, and the
consequences of the resulting impact. Therefore, identifying a defect
does not by itself establish the magnitude of risk.
7. Why is the tree's surrounding environment important during risk
assessment?
A. Environmental conditions can influence tree stability, loading,
growth, and target exposure
B. The surrounding environment has no relationship to tree risk
C. Only soil color matters during assessment
D. Environmental conditions determine the tree's species
Answer: A. Environmental conditions can influence tree stability,
loading, growth, and target exposure
Rationale: Trees interact continuously with their surroundings.
Changes in wind exposure, soil conditions, construction, drainage,
neighboring trees, grade, irrigation, and land use can influence tree
stability and structural performance. Environmental conditions can
