Key Differences Between Expert Witnesses and Fact Witnesses

James Komen, Board Certified Master Arborist WE-9909B & Registered Consulting Arborist #555

Consulting Arborists are hired to provide opinions and information about trees. Often, they are called to do so in the context of litigation as experts or even as lay witnesses, also known as fact witnesses. Consultants may be designated as experts for litigation, or they may provide more limited consulting services for the parties involved. How consultants are classified can have significant consequences for their testimony, involvement, and compensation.  Read More "Key Differences Between Expert Witnesses and Fact Witnesses"

Aerial Lift Best Practices

Phillip Kelley Phillip Kelley
Contract Climber & Owner of Samara Tree Preservation and Training
More articles by Phillip Kelley.

During the past few years I have observed a rise in aerial lift use for arboriculture. An influx of tracked and other mounted lifts have made tree canopies more accessible than ever before. These tools can make a potentially hazardous tree removal safer and more productive. All that being said, I have also noticed an increase in accidents and injuries involving aerial lift devices.   Read More "Aerial Lift Best Practices"

PNW-ISA Postpones Spring Education Workshops

Cristina Bowerman Cristina Bowerman
Executive Director
Learn more about Cristina Bowerman.

(Tigard, OR, Monday, March 16, 2020) PNW-ISA is postponing its March and April education programs to limit in-person contact. We are taking every precaution necessary to ensure our members remain healthy and safe. We have been in communication with instructors and facilities to determine rescheduling dates and will announce these dates as soon as they are finalized. When rescheduling, registrants will be notified and automatically moved into the new dates selected. If you are unable to attend the new date, you will be able to cancel your registration at that time and receive a refund.

To reduce exposure to COVID-19, PNW-ISA will be hosting conference calls/virtual meetings for its board and committees. We are doing everything possible to reduce exposure and adhering to recommendations for social distancing and isolation.

PNW-ISA will continue to monitor May activities such as our educational workshops and tree climbing competitions as we don’t want to put anyone at risk. We will continue to make informed decisions over the next few weeks and update members and registrants immediately.

We hope you and your loved ones remain healthy and safe as we navigate this time together.

Preparing for Urban Forest Pests: a Resource for Local Governments 

Benjamin Thompson Benjamin Thompson
Urban Forestry Program Manager, Washington State Department of Natural Resources
More articles by Benjamin Thompson.

Trees play a critical role in urban greenspaces benefiting both people and wildlife. These urban forests lie at the interface of trade, the movement of people, and neighboring forest and agricultural resources. The movement of goods and people brings with it the risk of introducing non-native urban forest pests, the worst of these pests can have costly, irreversible and lasting impacts to the landscapes they infest.   Read More "Preparing for Urban Forest Pests: a Resource for Local Governments "

Electrical Hazard Awareness Training

Phillip Kelley Phillip Kelley
Contract Climber & Owner of Samara Tree Preservation and Training
More articles by Phillip Kelley.

The presence of electrical hazards on a job site is one of the most common hazards we face as arborists. This is true regardless of where you are based, as there is always potential for an energized conductor to be present on nearly every job site we walk onto. This is probably why it is the third highest cause of fatalities among arborists in the U.S. This leads us to the question, if electricity is such a common hazard, how are people not recognizing it or trying to prevent it?

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Basics of Tree Biomechanics

Chris Madison Chris Madison
Madison Tree Consulting, LLC
Learn more about Chris Madison.

One of the greatest responsibilities of the professional arborist is to help our clients understand the many benefits that trees provide. But these benefits must outweigh the risks that are also present. Clients are mostly concerned with the risk side of the equation and contact us to know more about the likelihood of tree failure. This is where a strong understanding of biomechanics can help us. Read More "Basics of Tree Biomechanics"

PNW-ISA Education Update

Margo Thorp Margo Thorp
PNW-ISA Education Program Coordinator
More articles by Margo Thorp.

The PNW-ISA education program is now scheduling workshop offerings for the 2019-2020 year. Additional winter and spring workshops will be published in the coming months. Keep an eye on to stay in the loop on new and exciting opportunities. Read More "PNW-ISA Education Update"

To PPE or Not to PPE

Ryan Senechal Ryan Senechal

Although hardhats and hearing protection are, for the most part, in use by tree workers across the PNW, insidious attitudes are always lurking towards PPE whether it is aimed at premium protective equipment, PPE options not required by regulators (gloves, protective footwear or chainsaw pants in some parts of the chapter), PPE care, or the ongoing inspection and replacement of PPE. I expect that most tree care operations and their employees consider themselves to be compliant on the PPE front (particularly those that read this newsletter). If you feel that to be the case with your workplace, I have one question to ask:

Does your workplace request third-party observations and recommendations (formal or informal) on interventions that might improve the outcomes of worker health and safety, worker ergonomics and worker efficiency via PPE?

Hopefully the answer is yes.

It’s probably time to start talking about PPE as a program or system rather than a thick piece of plastic intended to keep skin from disappearing or bones from shattering. Read More "To PPE or Not to PPE"

Upcoming Tree Climbing Workshops

Margo Thorp Margo Thorp
PNW-ISA Education Program Coordinator
More articles by Margo Thorp.

PNW-ISA is offering two unique climbing workshops in Seattle, Washington in June. Registration is now open for the Women’s Tree Climbing Workshop and the Advanced Tree Climbing Workshop.

Women's Tree Climbing Workshop

June 7-9, Seattle, WAJoin the Waitlist

PNW-ISA presents Women's Tree Climbing Workshop. June 7-9, 2019, in Seattle, Washington. Enroll at

PNW-ISA has teamed up with the Women's Tree Climbing Workshop to offer a fun and safe space to learn to climb. Taught by International Tree Climbing Championship competitors Bear LeVangie and Melissa Levangie, this workshop is for women who have never climbed trees as well as those who have prior experience and want to improve their ability.

PNW-ISA thanks our generous 2019 sponsors who are helping to make the Women’s Tree Climbing Workshop possible:

Bartlett Tree Experts
BC Plant Health Care
Champion Tree Care
Christina Pfeiffer
D. Clark Arboriculture
Davey Tree Expert Company - Canada
Davey Tree Expert Company - USA
Fruitful Tree Care LLC
Morgan Holen and Associates
Out on a Limb Tree Co
Pfanner Canada
Radix Tree & Landscape Consulting
Renaissance Tree Care
Seattle Tree Care
Shelter Tree Inc.
Sonshine Tree Care
Sue Nicol
Sweaty Betty Tree Care
The Tree Service
Tree Solutions, Inc.
The Tree Stewards


We are looking for additional sponsors. Interested in sponsoring this year's PNW-ISA Women’s Tree Climbing Workshop? Your sponsorship will keep workshop registration fees affordable by helping to cover instructor travel costs, lodgings, food, climbing gear, and scholarships for participants in need. Please contact if you are able to support this event.

Advanced Tree Climbing Workshop

June 10, Seattle, WA - Register Now

PNW-ISA presents Advanced Tree Climbing Workshop. June 10, 2019, at the Talaris Conference Center in Seattle, Washington. Enroll at

While on the west coast, the LeVangie sisters will also lead an Advanced Tree Climbing Workshop for climbers who are beyond the basics. This workshop is open to all genders. Come learn advanced climbing techniques from an experienced team.

Full schedule and course descriptions for PNW-ISA workshops available at

Root Removal Best Practices

Richard Gessner
Monarch Consulting Arborists LLC

To keep up with research based changes in arboriculture and urban forestry we rely on guidance from a number of professional sources. The most important are the American National Standards Institute (ANSI) Practices and Limitations.  Because the ANSI A300 standards are written in a very austere style, they are interpreted and expanded upon in the ISA Best Management Practices (BMP’s). Both of these types of publications guide professionals in writing and implementing tree work.

Read More "Root Removal Best Practices"