Tree Risk Assessment for US Property Managers: Compare Levels

Choose the assessment level from the decision, tree population, targets and unresolved questions. ISA identifies limited visual (Level 1), basic (Level 2) and advanced (Level 3) assessments; its current Basic Tree Risk Assessment Form instructions are intended for Level 2, with other records needed for Levels 1 and 3.[5][5] Specify the scope and deliverable before comparing assessment quotes.

Compare Level 1, Level 2 and Level 3 assessments

Level 1: limited visual assessment

This is screening of an individual tree or population near specified targets, with observations limited by the agreed inspection method and access. Ask which trees, areas and visible conditions will be checked, how concerns will be escalated and which limitations will appear in the record.[5] Do not use a contractor’s free-estimate label as the professional definition or assume screening resolves a tree-specific concern.

Level 2: basic assessment

For a documented tree-specific ground assessment, ask for examination of the tree, site and targets and a record of the tools, access and visibility limits. ISA’s Level 2 form instructions include assignment details, tree identity, assessment timeframe, observations and analysis; the form may support a written report but is not itself intended to serve as the report.[5] State whether the commission includes a narrative explaining the findings and recommendations.

Level 3: advanced assessment

Advanced work investigates a defined uncertainty using appropriate specialist methods. Ask whether aerial inspection, investigation of internal decay, root assessment or another specialist method is appropriate for the particular concern. Ask the arborist to explain the question, proposed method and how its results could change the management recommendation. Level 3 is not a standard bundle of every test, nor a requirement that every tree progress through three levels.

Put the required scope in the proposal

• Tree identification: List every included tree using a site-plan reference, tag or another unambiguous identifier. Useful reports identify each assessed tree.[3]
• Targets and occupancy: Identify buildings, parking spaces, sidewalks, entrances, work areas and other exposed people, property or activities. Record occupancy patterns, target value and whether access can be restricted or the target moved.[1][2]
• Target zone: Require the arborist to define the relevant strike area and evaluate each tree in relation to specified targets.[1][2][5]
• Intended use: State that the report will support a choice among retention, monitoring, mitigation and removal rather than merely generate a removal estimate.
• Assessment level: Name the requested level and require approval before adding aerial inspection, root-flare excavation, internal-decay testing or other Level 3 work.[5]
• Examination: Include the crown, branches, trunk, root zone and site. Relevant factors include defect location and severity, decay, cracks, roots, canopy distribution, lean, health and site conditions.[1][2]
• Deliverables: Request photographs linked to tree IDs and findings. Tree MD says photographs are included in its PDF report; Align says it provides photographs when needed.[3][4]
• Next steps: Require mitigation alternatives, action priority and timing, plus a reassessment horizon when retention or monitoring is recommended.[1][2][3]

Require a decision-ready report

The report should explain the risk opinion, not merely assign a label.

• Evidence: Require the tree ID, observed defects, target exposure, risk rating, photographs and recommended action. When retention is recommended, require a reassessment horizon. Tree MD describes these elements in its PDF reports.[3]
• Method: Ask the arborist to name the rating system and explain what the assigned category means for each identified target. Purdue recommends a predetermined rating system with critical thresholds but does not specify those thresholds.[1][2]
• Limitations: Require the report to state the assessment level, inaccessible areas, material limitations and resulting uncertainty.[5]
• Recommendation: Request a reasoned choice among retention, monitoring, mitigation and removal, including feasible alternatives where appropriate.[1][2]

Put the written deliverable in the contract. Align says its detailed written report is available upon request rather than automatically included.[4] Because the cited guidance does not establish universal numeric thresholds or reassessment periods, require the arborist to define both for the assignment.[1][2]

Interpret the findings without presuming removal

• Retain: Keep the tree when the report supports an acceptable level of risk and routine management.[1][2]
• Monitor: Record the condition being watched, responsible party, next assessment date and triggers for earlier review. Reports for retained trees may include a reassessment horizon.[1][2][3]
• Mitigate: Consider pruning, structural support, plant health care, moving or removing the target, and modifying site conditions.[1][2][5]
• Remove: Treat removal as one possible recommendation rather than the automatic result of finding a defect. Purdue says all mitigation options should be considered before removal.[1][2]

Use risk labels cautiously. Align describes Low risk as generally suitable for monitoring or basic maintenance, Moderate as potentially mitigable with pruning or cabling, High as requiring strongly recommended action and Extreme as usually prompting removal advice. These are vendor descriptions, not nationwide numeric rules.[4]

Ask the arborist to connect each proposed measure to the defect or exposure it addresses. Where operations allow, changing parking, access or activity patterns may reduce target exposure without removing the tree.[1][2] Obtain separate scopes and prices for implementation.

Separate the risk opinion, estimate and approvals

Keep the arborist’s risk opinion separate from the contractor’s work estimate. The assessment report should connect identified trees and targets with observed conditions, risk findings, photographs, recommended actions and, when retention is advised, a reassessment horizon.[3] Implementation estimates should reference the assessed tree IDs and selected recommendations.

Ask for a separate price for the assessment, written report and any proposed advanced work. If the same firm also quotes for pruning or removal, request a clear distinction between its risk recommendation and its implementation estimate, together with any relevant conflict-of-interest arrangements.

The cited sources do not set out local tree rules. Separately check with the municipality or utility whether protected-tree, removal, replacement, emergency, appeal or utility-clearance requirements apply. Local permit authorization is separate from an arborist’s recommendation.

What to confirm with each provider

• Assessment price and any added cost for Level 3 work
• Whether the written report, photographs and explanation of findings are included
• Report-delivery time and scheduling deadlines
• Payment, contract, cancellation and refund terms
• Professional-liability insurance limits and conflict-of-interest policies
• The qualifications of the arborist assigned to the assessment

Obtain all of these terms in the proposal.

Assign follow-up and preserve the record

A retention or monitoring decision needs a responsible party, deadline and record. Assign responsibility for mitigation, routine care, retaining inspection records and scheduling the next assessment.[1][2] Preserve each inspection so changes in tree health and structure can be tracked over time.[1][2]

Purdue recommends annual inspections in active-use areas, inspections after storms and more frequent monitoring for trees with previous failures or problematic structure.[1][2] Calendar any tree-specific reassessment horizon and seek earlier professional review after a storm or new failure.[1][2][3]

References

1. Tree Risk Management: What Every Property Owner Needs to Know (purdue.edu)
2. FNR-475-W Purdue extension Author Lindsey Purcell, Urban Forestry Specialist, (purdue.edu)
3. Hazardous Tree Assessment | TreeMDs (treemds.com)
4. Tree Risk Assessment — Align Tree Management (aligntreemgmt.com)
5. ISA — Using the Basic Tree Risk Assessment Form (2025) (isa-arbor.com)