Short Answer

An arborist expert witness may examine physical evidence from the tree and site, photographs and videos, maintenance and inspection records, construction documents, property information, weather data, prior reports, correspondence, and other materials relevant to the tree-related questions in the case. The evidence reviewed depends on the circumstances and on what the arborist has been asked to evaluate.

Why Is Evidence Important in a Tree Case?

Tree disputes often involve events that happened months or even years before an expert becomes involved.

A tree may already have been removed. A stump may have been ground. Construction may have changed the property. Storm cleanup may have eliminated important physical evidence.

For that reason, an arborist often has to reconstruct what occurred by examining multiple sources of information.

The objective is to develop an evidence-based understanding of the tree, the property, its condition before the incident, and the circumstances surrounding the loss or dispute.

What Physical Evidence May an Arborist Examine?

When physical evidence is still available, an arborist may inspect:

• The standing tree

• A fallen tree

• The trunk

• Branches

• The stump

• Roots

• Failure surfaces

• Decayed or damaged wood

• Pruning cuts

• Wounds

• Soil conditions

• Nearby structures

• The surrounding landscape

• Construction areas

• Other trees on the property

Physical examination can provide information that photographs alone may not capture.

The type of evidence that matters depends on the questions involved in the particular case.

Why Are Photographs and Videos Important?

Photographs can be extremely useful, particularly when the original tree or site has changed.

Useful photographs may show:

• The tree before the incident

• The condition of the canopy

• The tree's location

• Nearby buildings or structures

• Previous damage or defects

• The property before construction

• Conditions immediately after a tree failure

• Cut branches or roots

• Damage to property

• The stump after a tree has been removed

• Changes made to the site

Videos may provide additional context concerning the tree, surrounding conditions, weather, damage, or the sequence of events.

The more accurately photographs can be dated and placed within the timeline of the dispute, the more useful they may become.

Can Old Photographs Be Useful?

Yes.

Older photographs may help an arborist understand how a tree or property changed over time.

Historical photographs can sometimes provide information about:

• Tree size

• Canopy development

• Previous pruning

• Construction activity

• Changes to surrounding trees

• Property alterations

• Decline or damage

• The condition of the landscape before a disputed event

When a tree has already been destroyed or removed, older images may become especially important.

Are Tree Maintenance Records Important?

They can be.

Depending on the case, an arborist may review records concerning:

• Tree inspections

• Pruning

• Removal recommendations

• Fertilization or treatment

• Cabling or support systems

• Pest or disease treatment

• Previous storm damage

• Tree risk assessments

• Recommendations made by arborists or tree companies

• Work orders and invoices

These records may help establish what was known about the tree and what work had previously been performed.

The significance of those records depends on the circumstances and the issues being evaluated.

What If There Are No Tree Maintenance Records?

The absence of written records does not necessarily determine the outcome of a tree case.

Many property owners do not maintain formal records for every tree.

An arborist may still be able to evaluate the available physical evidence, photographs, witness information, site conditions, and other relevant materials.

The strength of any conclusion depends on the quality and amount of evidence available.

Can Construction Records Be Important?

Yes, particularly when construction damage is alleged.

An arborist may review materials such as:

• Site plans

• Construction drawings

• Excavation plans

• Utility plans

• Grading information

• Landscape plans

• Tree protection plans

• Construction photographs

• Work schedules

• Contractor records

• Inspection reports

These materials may help determine how close construction activity occurred to a tree and whether roots, soil, drainage, or other growing conditions may have been affected.

Does an Arborist Review Property Surveys?

A property survey may be useful when the location of a tree relative to a property boundary is important.

Boundary disputes can become significant when a case involves:

• Tree removal

• Cutting or pruning

• Root damage

• Neighbor disputes

• Trespass allegations

• Construction activity

An arborist can evaluate the tree and its location, while legal questions concerning ownership and property boundaries should be addressed by the appropriate legal professionals.

Can Weather Information Be Used in a Tree Failure Investigation?

Yes.

Weather may be relevant when a tree or branch fails during a storm or other severe conditions.

Depending on the assignment, information concerning:

• Wind

• Rain

• Saturated soil

• Lightning

• Snow or ice

• Severe storms

• Previous weather events

may help provide context for the failure.

Weather alone does not necessarily explain why a tree failed. The arborist may also need to consider the tree's structure, roots, condition, site, and other factors.

Are Witness Statements Useful?

They can be.

People who observed the tree before or after an incident may provide information about:

• The tree's appearance

• Previous branch failures

• Leaning

• Visible damage

• Construction activity

• Pruning

• Storm conditions

• Complaints or concerns about the tree

• The sequence of events surrounding an incident

An expert should distinguish between observations and conclusions.

A witness may accurately describe what they saw, but determining the arboricultural significance of that observation may require professional analysis.

What Documents Might an Arborist Review?

Depending on the assignment, an arborist may review:

• Arborist reports

• Tree-company reports

• Inspection records

• Appraisals

• Insurance documents

• Construction records

• Property records

• Surveys

• Photographs

• Emails

• Text messages

• Letters

• Contracts

• Maintenance records

• Deposition testimony

• Other expert reports

• Relevant portions of legal filings

The particular documents reviewed depend on the issues the arborist has been retained to address.

Does an Arborist Review the Other Expert's Report?

In litigation, an arborist may be asked to review opinions or reports prepared by another expert.

That review may involve evaluating:

• The evidence relied upon

• The methods used

• The arboricultural assumptions made

• Whether the conclusions are supported by the available information

• Whether accepted professional practices were appropriately considered

Professional disagreement does not automatically mean another expert is wrong.

The goal should be to evaluate whether opinions are supported by the evidence and professional reasoning.

What If the Tree Has Already Been Removed?

An investigation may still be possible.

When the original tree is no longer available, the arborist may rely more heavily on:

• Before-and-after photographs

• Stump measurements

• Historical imagery

• Tree-care records

• Witness observations

• Reports

• Property photographs

• Remaining tree material

• Construction documentation

• Other evidence concerning the tree

However, removal can eliminate information that would have been available during an on-site examination.

That is why preserving evidence can be important when a tree incident may lead to litigation, an insurance claim, or a significant dispute.

Why Should Evidence Be Preserved Early?

Tree evidence can disappear quickly.

After an incident:

• Fallen trees may be cut apart

• Branches may be chipped

• Stumps may be ground

• Roots may be excavated

• Property damage may be repaired

• Construction may continue

• Landscapes may be changed

Once evidence disappears, some questions may become much more difficult to answer.

When practical and safe, photographing the tree, the site, the damage, and important physical evidence before cleanup can help preserve information for later evaluation.

Does More Evidence Always Mean a Stronger Opinion?

Not necessarily.

The quality and relevance of the evidence matter more than simply having a large quantity of material.

An expert must determine which information is reliable, relevant, and useful to the questions being evaluated.

A professional opinion should also acknowledge important limitations when evidence is incomplete.

An expert should not claim greater certainty than the available evidence supports.

What Is the Arborist Expert Witness Trying to Determine?

That depends on the case.

Tree-related expert assignments may involve questions such as:

• Why did a tree fail?

• What condition was the tree in before failure?

• Were significant defects present?

• Could important conditions reasonably have been recognized?

• Did construction damage the tree?

• Did pruning or root cutting affect the tree?

• What was the value of the tree?

• How much value was lost because of damage?

• Were accepted arboricultural practices followed?

• What tree-related evidence supports or contradicts a particular claim?

The expert's job is to evaluate those questions independently using the available evidence and appropriate arboricultural expertise.

About Marty Shaw, RCA

Marty Shaw, RCA is a consulting arborist, investigator, tree and plant appraiser, author, and expert witness with decades of experience addressing complex tree-related matters.

His work includes forensic investigations, tree failures, property disputes, tree and landscape appraisal, construction damage, insurance matters, tree risk assessment, and litigation involving trees.

Green Season Consulting provides independent arboricultural expertise to attorneys, insurance professionals, property owners, organizations, and others who need professional analysis of complex tree-related evidence.

Contact Marty Shaw About a Case:

Email: expert@greenseasonconsulting.com Call: (615) 794-4377

This information is provided for general educational purposes and is not legal advice. Legal questions involving liability, negligence, ownership, evidence, damages, or other legal rights should be discussed with a qualified attorney.