Contact Us

Email us
Phone: +1.678.367.0981
Fax: +1.240.547.1795

Mailing Address

International Society of Arboriculture
PO Box 191
Annapolis Junction, MD 20701
United States

Physical Address

International Society of Arboriculture
270 Peachtree St NW, Suite 1900
Atlanta, GA 30303
United States

Order Delays Due to Physical Inventory

Due to ISA's annual physical inventory, orders placed between
2 p.m. EDT, Thursday, 20 June 2019, and 11:59 p.m. EDT, Friday 28 June 2019, will not ship until the week of 1 July 2019

Please plan your ordering accordingly.

We will resume regular turnaround times
1 July 2019.

Thank your for your patience.

Questions? Please call the customer service team at (678) 367-0981.

    Climbers' CornerTree Academy

    “Reduce the Crown, Retain the Tree”


    The presentation examines aspects of crown reduction from several different perspectives. An understanding of tree morphology and natural tree survival strategies informs management approaches for aging trees. Many mature trees have structural constraints that are not correctable in one pruning application. These trees can however be improved over time, utilizing crown reduction and thinning techniques. If too much is cut, large wounds can lead to significant decay and structural weakness. If too little is cut, the tree may break, also causing large, obscure wounds. How do we find the appropriate dose and still leave the tree looking natural and reasonably safe?

    Philip van Wassenaer, a consulting arborist, will introduce  natural tree survival strategies and  discuss several significant trees that have been evaluated and retained using a variety of risk assessment techniques and how those assessments resulted in targeted crown reduction prescriptions. Ryan Redvers, a practicing arborist, will present detailed case studies on trees which he has successfully reduced and retained for clients in Southern Ontario. Each case will include; tree description; significant problems seen in the structure; before and after reduction pruning photos; a detailed prescription; the number of cuts in each length range; the diameter of cuts in each length range; the combined mass of removed pieces; an explanation of the process including tools, technique, objectives, references; explanation of the concepts  practiced , including taper, form, balance, branch ratio, spacing, reduction, raising, thinning, reduce/remove/retain.  

    The audience will leave with a further understanding of how thoughtful crown reductions can be incorporated into their repertoire of techniques to help conserve trees   rather than removing them.


    Philip van Wassenaer, B.Sc. Environmental Sciences, Master of Forest Conservation, is the principal consultant for Urban Forest Innovations, Inc., which specializes in the preservation, enhancement, and management of the urban forest using a research- and science-based approach. He is an ISA Certified Arborist, member of ASCA , a Past President and Director of the    Ontario Urban Forest Council and a 2009 recipient of the ISA True Professionals of Arboriculture Award.

    An ISA certified arborist since 2004, Ryan Redvers has always been passionate and curious about trees, physics, and art and how the three fit together. For a solid ten years he has focused on his pruning  practice , incorporating concepts from Gilman, Coder, Shigo, and others. Ryan knows trees from the inside out!

    Climbers' CornerTree Academy

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