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Why Trees Fail – The Physics of Windstorm Tree Failure

April 17 @ 1:15 pm - 5:00 pm
Instructor: Jim Flott CEUs: 3.5 ALMTU / 1.5 B-S, 1.0 B-P, 1.0 B-M

PNW-ISA is hosting two workshops in Anchorage. Take advantage of a morning or afternoon workshop on April 17. Enroll in BOTH and get $25 off the cost of the afternoon workshop.


This workshop provides a solid foundation for arborists of all skill and experience levels to aid in assessing why trees fail in storm events and improves their ability to assess risk.

There has been a proliferation of tree anchorage and tree biomechanics research in the last decade. Understanding why trees fail involves application of this recent research in order to discard outdated beliefs, generalizations, anecdotes, and industry myths and misinformation. Tree, root, and crown attributes, loads, weather, and tree biomechanics will be discussed in relation to wind storms.

The workshop and discussion will review, synthesize and integrate several research findings to try to understand how and why some trees fail, some do not, and some break along the trunk, while others uproot.


Location: Atwood Conference Center, Rooms 102 and 104, 550 West Seventh Ave, Anchorage, AK 99501

  • 1:15pm – 2:45pm
    • Root strength, architecture and tree anchorage: Tree anchorage, tree form, root attributes characterized in relation to wind forces
    • Tree failure patterns: Discussion and illustration of the types of tree failures in storm events
    • Weather impacts: Types of weather patterns associated with tree failures, wind dynamic effects on tree failure
  • 2:45pm – 3:00pm, Break
  • 3:00pm-5:00pm
    • Tree biomechanics: Connecting tree biology to engineering principles in relation to failure in storm events
    • Arboriculture practices and structural defects: Applying principles learned today for use in practice.


Jim Flott is president of Community Forestry Consultants, Inc. (CFC). CFC provides TreeWorks™ tree management software; inventories and appraisals; management plans; risk assessment and risk management plans; tree preservation plans; diagnosis; expert witness; forensic investigations; urban forestry program reviews; training workshops; and urban forestry, arboriculture, and horticulture consulting services to individuals, corporations, universities, municipalities, county and state agencies, cemeteries, and golf courses in the United States and Canada. He received his B.S. degree in horticulture from Iowa State University and his M.S. degree in forest pathology from the University of Arizona and has over 40 years work experience in the horticulture, urban forestry and arboriculture industries. He is an ISA certified arborist and certified municipal specialist; American Society of Consulting Arborists registered consulting arborist; PNW-ISA TRACE instructor and certified tree risk assessor; and ISA TRAQ instructor and assessor.

Refund Policy

  • Cancellations made at least 10 days prior to the event will be refunded at 100%.
  • Cancellations made within 5-9 days of the event will be refunded at 75%.
  • Cancellations made within 1-4 days of the event will be refunded at 50%.
  • Refunds will not be made available for no-shows.

Late Registration

  • Participants are expected to enroll prior to the registration deadline.
  • Participants can register at the door of the event only if space is available. Individuals will need to pack their own lunch.
  • Late registration is possible on a space available basis. You can contact our office at (800) 335-4391. There may, or may not be, room available for those who show up without registering ahead of time for the workshop. We encourage you to register for the workshop in advance.

Allied Professionals are members of allied organizations. See our list of qualifying organizations.


Atwood Conference Center
550 West Seventh Ave
Anchorage, AK 99501 United States
(907) 269-0330