Tree Assessment and Valuation

1. Tree Assessment

• LHAP 305 D.Ballard 2025

2. What will we cover?

• Tree risk assessments

Levels of tree risk assessment Risk mitigation Methods of tree valuation

• Tree inventory systems
• Codes and regulations

3. Tree Risk Assessment Qualification

• Also known as TRAQ

As an ISA certified arborist, you could take training to become TRAQ certified. https://www.isa-arbor.com/Credentials/ISA-Tree-Risk-Assessment-Qualification

Arboriculture Canada also has the Comprehensive Tree Risk Management Qualification course https://www.arborcanada.com/courses-1/comprehensive-tree-risk-management-qualification

4. What is Tree Risk Assessment?

Tree Risk Assessment - The process used to identify, analyze, and evaluate tree risk.

Tree Risk Management - is the application of policies, procedures, and practices used to identify, evaluate, mitigate, monitor, and communicate tree risk.

The Farmer Fred Rant. (2010, June 03). Tree Goes boom. Film at 11. The Farmer Fred Rant. Retrieved Oct 31, 2025

5. Levels of Tree Risk Assessment

Level 1 - Limited visual assessment of 1 or more trees.

Identify trees and the location Find the best route for inspection

Assess from one perspective - walking by, driving by

Record what trees need mitigation or further assessment

Evaluate the risk based on what you saw Submit report with recommendations

Washington Tree Services. (n.d.). Tree Inspection & Evaluation. Washington Tree Services. Retrieved Oct 31, 2025

6. Levels of Tree Risk Assessment

Level 2 - Basic assessment - Detailed visual inspection of the tree, its surroundings and the targets involved.

• Locate and identify trees

Determine targets and target zone Inspect the site and review site history

Visual inspection of tree - binoculars, mallet, probe or trowel

Assess tree loads, leans, and general tree health

• Record observations

Determine likelihood of failure, as well as impact and consequences

Submit report with mitigation options and degree of risk involved

Frey, F. (n.d.). 5 Signs It’s Time to Schedule a Tree Risk Assessment (TRA). Vintage Tree Care INC. Retrieved Oct 31, 2025

7. Levels of Tree Risk Assessment

Level 3 - Advanced assessment - detailed information on tree parts, defects, targets and site conditions

Aerial inspections - Climbers, drones, UAV photographs

Detailed target assessment - values, occupancy rates

Detailed site assessment - history, soil testing

Decay testing - boring, high end technologies Health evaluation - from roots to shoots

Storm/ wind analysis Assessing trunk leans Load testing- hand pulls, pull test with sensors

• Lab tests

Green Leaf Tree Services LTD. (n.d.). Certified Tree Risk Assessment. Green Leaf Tree Services LTD. Retrieved Oct 31, 2025

Samsara Tree Care. (n.d.). Tree Inspections & Arborist Reports By Samsara. Samsara Tree Care. Retrieved Oct 31, 2025

8. Tree Risk Assessment

Risk - combination of likelihood of tree failure, likelihood of impact, and consequences of failure.

Tree risk assessment - Process used to identify, analyze, and evaluate tree risk.

Tree risk evaluation - Comparing the risk involved with a tree against the standards of a client

Diameter at breast height (DBH) also known as diameter at standard height (DSH) measured at 1.4 meters above the ground

Find circumference of trunk Then calculate DBH or DSH = circumference / π (Pi)

9. Tree Risk Assessment - Targets

Targets - Anything, that during the course of a tree failure, can be harmed or damaged

• Static targets
• Movable targets
• Mobile targets

Target Zone - area in which the tree or branch is likely to strike

Occupancy rates - amount of time targets are within the target zone

Constant, frequent, occasional, rare Likelihood of Impact - High to very low

Consequences of failure -Severe, significant, minor, negligible

Durand-Wood, E. (2023, June 29). An Inconvenient Tree. Strong Towns. Retrieved Oct 31, 2025

10. Example - Targets

A large Poplar Tree is growing alone in a Park, in Calgary. It is a Saturday in the middle of summer. It has a large dead limb overhanging the sidewalk.

What are the targets?

What are the assumed occupancy rates?

What is the Likelihood of Impact?

What consequences could we assume?

What level of consequences would you put this under?

Marrickville Municipality. (2015, Aug 16). Our poor poplar trees. Saving Our trees - Marrickville Municipality. Retrieved Oct 31, 2025

11. Tree Risk Assessment - Tree Failure

Tree failure- Breakage of a stem, branch, or roots, or loss of mechanical support in the root system

Anderson, J. (n.d.). Stump the Forester: What Are Codominant Stems? Florida urban Forestry Council. Retrieved Oct 31, 2025

Lester, D. (2015, Feb 14). Storm-damaged trees require careful assessment for care. Recordonline.com. Retrieved Oct 31, 2025

12. Tree Risk Assessment - Tree Failure

Likelihood of failure - The chance of a tree or tree part failure occurring in a specified time frame.

Defects and structural conditions Loads Site conditions

• Weather
• Time frame
• Imminent, probable, possible, Improbable

13. Tree Risk Assessment - Site Inspection

• History of failures

Typical weather for the area Tree experiencing new exposures

• Evidence of root damage

Evidence of drought or flooding New soil conditions

• Trees growing on slopes
• New construction in area
• Restrictions on tree

14. Steps to Develop a Tree Risk Rating

• Identify possible targets

Identify tree parts that could fail Categorize the likelihood of failure

Categorize the likelihood of impact For each failure/target combination

Categorize the likelihood of failure and impact Assess consequences of failure

Categorize the risk.

Managing Tree Risk 101. (n.d.). TRAQ Tree Risk Management Methodology. Managing Tree Risk 101. Retrieved Oct 30, 2025

15. Risk Mitigation

Mitigation - action taken to reduce risk.

• Target management
• Tree based mitigation

Residual risk - The risks remaining after or caused by the mitigation attempt.

16. Tree Valuation

• Know your trees worth

17. Tree Valuation

Tree valuation is how we put a dollar value on a tree in a landscape

Reasons to have a tree valued Unexpected losses Tort Claims

• Insurance Claims
• Tax deductions
• Real estate assessment
• Proactive planning

18. Tree Valuation

What do we look for when appraising a tree?

• The species
• The condition
• The Size
• The Location

19. Depreciation of Value

Depreciation is the loss of value to estimate the actual value of a tree in a landscape.

• Depreciation depends on;
• Condition of the tree
• Functional Limitations
• External Limitations

20. Tree Appraisal Methods

There are a few methods for doing so Sales comparison approach

• Income approach
• Cost approach
• Replacement Cost Approach
• Trunk formula technique (TFT)

21. Tree Valuation

• Sales comparison approach

Estimates the value of having trees on the property by comparing it to a similar properties value without the trees.

Not commonly used because it's unlikely to find properties that are similar enough.

22. Tree Valuation

• Income Approach

Value is based on the economic benefits of the tree.

Both current and future incomes from it.

• Example

A peach tree produces 100 kg of peaches in a year. The grower makes an income of $5 per kg each year. The tree was expected to last 8 years before it was sprayed with roundup by a disgruntled employee.

23. Tree Valuation

• Cost Approach

Determines value based on current costs to replace or reproduce a tree of the same species and of similar size.

• Replacement cost method

Trunk Formula Method.

24. Tree Valuation

• Cost Approach - Replacement cost Method

Used when the nursery can supply the client with a tree that is the same species and of the same caliper.

Value = Cost of purchase + cost of planting

25. Tree Valuation

Trunk Formula Technique (TFT) or Trunk Formula Method

Meant for valuing large trees that would be difficult to replace with one of equal species and size.

26. Tree Valuation

Find CSA of subject tree calculate DBH = circumference / π (Pi)

CSA = Diameter x Diameter X .7854 (.7854 is a constant)

Find unit tree cost - cost per square inch of replacement tree

Find cost of new tree and cost to transport and install

Find caliper size of tree you will purchase FInd CSA = Diameter x Diameter X .7854

• Find Basic reproduction cost

(CSA of subject tree/ CSA of replacement tree) x total replacement cost = basic reproduction costs

Purcell, L. (n.d.). Tree Appraisal and the Value of Trees. Purdue Extension. Retrieved September 15, 2025

27. Tree Valuation

Condition rating - Overall tree health condition in percentage

Good health and structure - 100% Defects over half of the tree - 50%

Functional limitations - Characteristics of the tree itself that reduce its practical value

Messy fruiting tree or trees prone to branches breaking

Growing into power lines or against a building Minor inconvenience- 5% reduction

• Major Inconvenience- up to 50%

External limitations - problems out of the owners control that affect the tree.

Easements or right-of-ways.

Minor restriction - 5% reduction Major conflicts - up to 50%

Purcell, L. (n.d.). Tree Appraisal and the Value of Trees. Purdue Extension. Retrieved September 15, 2025

28. Tree Valuation

Now that you have all these values, you can find your depreciated reproduction cost

Multiply the basic reproduction cost by all depreciation percentages

BRC x CR X FL X EL

Add in any additional costs Post planting care, old tree removal

This will give you your appraisal value

Purcell, L. (n.d.). Tree Appraisal and the Value of Trees. Purdue Extension. Retrieved September 15, 2025

29. Lets try an example

An Ohio Buckeye is growing beside an office building. The tree has great structure and no defects. It is growing well with lots of space and no external obstructions. (Assume no depreciation).

The owners would like a value on the tree.

You measure circumference at 1.4 meters from the ground and find it to be 100cm.

The local nursery has 10 cm caliper Ohio Buckeyes that will cost $1000 for purchase and install.

There are no additional costs.

Find a value for the Ohio Buckeye to the nearest $1000.

30. Tree Inventory Systems

Record of species, locations, characteristics, and assessments of trees and groups of trees in a defined area (Street, park, urban centre, etc)

These inventories are used to Find number of trees

• Find value of trees

Variety of species in an area IPM Budgeting Planning and development

These inventories likely include Tree species and diameter

• Location
• Condition
• Past maintenance
• More advanced inventories include Site information
• Crown dimensions
• Maintenance schedule
• Risk assessment

Value https://www.itreetools.org/ https://maps.calgary.ca/TreeSchedule/

31. Codes and Regulations

ANSI 300 https://sullivansisland.sc.gov/sites/sullivansisland/files/Documents/Tree%20Preservation/ANSI%20300-%20Pruning%20Standards.pdf

ANSI Z133 https://cdn.ymaws.com/www.ohioforest.org/resource/resmgr/masterlogger/z133.pdf

OHS - Part 34 and 39 https://kings-printer.alberta.ca/documents/OHS/OHS Code_March_31,_2025_(rep_s850)_only.pdf

32. Bibliography

Anderson, J. (n.d.). Stump the Forester: What Are Codominant Stems? Florida urban Forestry Council. Retrieved Oct 31, 2025, from https://fufc.org/what-are-codominant-stems/

Dunster, J. A., Smiley, E. T., Matheny, N. P., & Lilly, S. (2017). Tree Risk Assessment Manual. International Society of Arboriculture.

Durand-Wood, E. (2023, June 29). An Inconvenient Tree. Strong Towns. Retrieved Oct 31, 2025, from https://archive.strongtowns.org/journal/2023/6/29/an-inconvenient-tree

Frey, F. (n.d.). 5 Signs It’s Time to Schedule a Tree Risk Assessment (TRA). Vintage Tree Care INC. Retrieved Oct 31, 2025, from https://www.vintagetreecare.com/signs-to-schedule-a-tree-risk-assessment

Green Leaf Tree Services LTD. (n.d.). Certified Tree Risk Assessment. Green Leaf Tree Services LTD. Retrieved Oct 31, 2025, from https://www.greenleaftree.ca/tree-risk-assessment

Lester, D. (2015, Feb 14). Storm-damaged trees require careful assessment for care. Recordonline.com. Retrieved Oct 31, 2025, from https://www.recordonline.com/story/lifestyle/home-garden/2015/02/14/storm-damaged-trees-require-careful/35189115007/

Managing Tree Risk 101. (n.d.). TRAQ Tree Risk Management Methodology. Managing Tree Risk 101. Retrieved Oct 30, 2025, from https://managingtreerisk101.net/traq-tree-risk-management-methodology/

Marrickville Municipality. (2015, Aug 16). Our poor poplar trees. Saving Our trees - Marrickville Municipality. Retrieved Oct 31, 2025, from https://savingourtrees.wordpress.com/2015/08/16/our-poor-poplar-trees/

Purcell, L. (n.d.). Tree Appraisal and the Value of Trees. Purdue Extension. Retrieved September 15, 2025, from https://www.extension.purdue.edu/extmedia/fnr/FNR-473-W.pdf

Samsara Tree Care. (n.d.). Tree Inspections & Arborist Reports By Samsara. Samsara Tree Care. Retrieved Oct 31, 2025, from https://samsaratreecare.com/tree-inspections-arborist-reports/

The Farmer Fred Rant. (2010, June 03). Tree Goes boom. Film at 11. The Farmer Fred Rant. Retrieved Oct 31, 2025, from http://farmerfredrant.blogspot.com/2010/06/tree-goes-boom-film-at-11.html

Washington Tree Services. (n.d.). Tree Inspection & Evaluation. Washington Tree Services. Retrieved Oct 31, 2025, from https://www.washingtontreeservices.com/tree-services/tree-inspection-and-evaluation/

Referenced Links

• https://www.isa-arbor.com/Credentials/ISA-Tree-Risk-Assessment-Qualification
• https://www.arborcanada.com/courses-1/comprehensive-tree-risk-management-qualification
• https://www.itreetools.org/
• https://maps.calgary.ca/TreeSchedule/
• https://sullivansisland.sc.gov/sites/sullivansisland/files/Documents/Tree%20Preservation/ANSI%20300-%20Pruning%20Standards.pdf
• https://cdn.ymaws.com/www.ohioforest.org/resource/resmgr/masterlogger/z133.pdf
• https://kings-printer.alberta.ca/documents/OHS/OHS Code_March_31,_2025_(rep_s850
• https://fufc.org/what-are-codominant-stems/
• https://archive.strongtowns.org/journal/2023/6/29/an-inconvenient-tree
• https://www.vintagetreecare.com/signs-to-schedule-a-tree-risk-assessment
• https://www.greenleaftree.ca/tree-risk-assessment
• https://www.recordonline.com/story/lifestyle/home-garden/2015/02/14/storm-damaged-trees-require-careful/35189115007/
• https://managingtreerisk101.net/traq-tree-risk-management-methodology/
• https://savingourtrees.wordpress.com/2015/08/16/our-poor-poplar-trees/
• https://www.extension.purdue.edu/extmedia/fnr/FNR-473-W.pdf
• https://samsaratreecare.com/tree-inspections-arborist-reports/
• http://farmerfredrant.blogspot.com/2010/06/tree-goes-boom-film-at-11.html
• https://www.washingtontreeservices.com/tree-services/tree-inspection-and-evaluation/