September 2023

Characterizing Strain and Load Transfer in the Root Flair

Greg Dahle, Ph.D., BCMA, TRAQ

West Virginia University

As the number and intensity of storms increase, we are likely to see an increase in tree failures around our homes, roadways or utility lines. Uprooting is one of the more common and disastrous modes of tree failure. The International Tree Failure Database (ITFD) indicates that root failures make up 35.6% of total tree failures. Arborists consider many variables when assessing the likelihood of failure during tree risk assessments and researchers have suggested that a key area of interest is the root-soil plate system.

Researchers at West Virginia University and the Morton Arboretum used static load pull tests to map mechanical strain (tissue deformation) along the root flares of pin oak trees. Strain was measured using a stereo camera system and mapped by a digital image correlation system. The magnitude of strain was found to be the same between the windward and leeward roots. It appears that the load and strain is equally distributed in the root system during static load trials, at least in terms of the direction of the loading.

This information is important to practitioner and tree risk assessor, as it demonstrates that both the leeward and windward roots are equally important in terms of tree stability. As trees are increasing important in the urban landscape, arborist should take care to preserve the roots systems to maintain the health and structural stability of individual trees. The knowledge gained from this study suggests that arborists should consider all structural roots important in terms of load distribution, regardless of dominant wind loading regimes.

What An Amazing Tour des Trees!

Our Tour des Trees riders had a blast in Nevada and California this week. So far, we have raised $285,000 and we are not done yet! The TREE Fund Board of Trustees has challenged us to up our fundraising goal and get to $375,000 by October 18. You can donate at www.tourdestrees.org.

Want to see photos from our trip? Check out our Flickr page and get inspired to join us at the 2024 Tour des Trees! Info for 2024 will be released this winter.

Lead Donors

We are deeply grateful to the following people and organizations who contributed $2,500 or more to the TREE Fund in August 2023:

Higley Fund of the Cleveland Foundation

Arbor Day Foundation

Western Chapter ISA

Kelly Frady

Ashley Mulis

Anderson's Tree Care Specialists, Inc.

Theresa L. Williams

See the full list of lead donors who make our vital tree research and education work possible on our website.

Free Webinars

TREE Fund is proud to partner with the Alabama Cooperative Extension System to bring you free education offerings. We are now able to accommodate up to 3,000 participants! 

Tuesday, November 28. Noon CDT.

Presenters: Dr. Susan Day and Laura Grant

Analyzing timing and causes of individual tree loss after land development: Insights for urban forest management

Registration will be available two weeks prior to the webinar.

TREE Fund’s 1-hour webinars are free and offer 1.0 CEU credit for live broadcasts from the International Society of Arboriculture and the Society of American Foresters. Registration and information will become available on our website approximately two weeks before each webinar date.

Upcoming Webinars (registration opens about two weeks prior)

• Our 2024 Webinar Series scheduled will be released after the new year.

Missed a webinar? Watch it anytime on our website.

CEU Credit for Recorded Webinar

TREE Fund now offers ISA CEU credits for one recorded webinar: "Loading of a Tie-in Point While Climbing." If you missed this webinar, you can now watch the recording and earn ISA CEU credits by completing a 20 question quiz with 80% accuracy. Learn more on our website.

TREE Fund is a 501(c)3 nonprofit whose mission is to support scientific discovery and dissemination of new knowledge in the fields of arboriculture and urban forestry.