Tree Biomechanics

 Stormwise: Resilient Trees, Resilient Power.

Amana Bunce climbing
Figure 1: Amanda Bunce, a masters degree student in the department of Natural Resources and the Environment, climbs a 30 foot ladder in order to affix a monitoring device to a red oak. (Sheila Foran/UConn Photo)

UConn graduate student Amanda Bunce (figure 1) studies how trees  move in the wind. As a researcher, she's measuring changes in tree sway dynamics with the intent to evaluate and improve the resiliency of the forest edge in storm-force winds. Recent destructive storm events in the northeast have inspired utility companies, researchers and other collaborators to work together on this project, in an attempt to better prepare our communities. In the past, tree sway studies have been focused primarily on conifers where the timber industry can suffer severe economic losses from storm damage, and little attention has been paid to deciduous hardwood species. A critical look at how to best manage northern hardwood forests is long overdue, and UConn and its partners are taking the initiative. 

Looking at the entire forest

To protect our power lines from tree damage during a storm, power companies have initiated trimming cycles where every 3-5 years they cut tree limbs 8-10 feet back from the lines. This method is much better than no preparation for storm events at all, but it does nothing in the event of whole trees falling. Entire tree failure is the cause of over half of tree-related power outages, and along with branch failure account for 90% of all outages during a storm. Stormwise suggests taking a more holistic approach by looking at not just at offending limbs, or even whole trees , but at the entire forest (figure 2). By using forestry management practices in these fragmented edge woods we can create a more stable woodland situation.

pre post trimming biomechanics
Figure 2: Examples of forest structure before and after a Stormwise thinning

 

Trees adapt to wind

Stormwise management aims to maintain the benefits of the woodland while improving its resiliency in a storm. One scenario involves thinning the forest edge up to 100 ft. back from the wires, removing dangerous and unhealthy trees, or trees that have run the course of their lifespan. Straight, strong trees and species that best hold up to wind are selected to remain standing and provided with space to grow. Thinning to provide space for the crowns of these selected trees allows a more even distribution of sunlight allowing remaining trees to grow a more balanced crown and also allows for more wind flow within the forest edge. Trees exposed to more wind change their growth patterns accordingly. They become stouter at the base, gaining girth and a more substantive root structure, and over time become more wind firm. 

 With the potential effects of a warming climate including increased frequency and severity of storms, this research will provide future forest managers with the tools they need to maintain New England’s forested beauty while protecting the safety of its people and communities.The Stormwise project hopes to span the northeast and involve a wide variety of people and stakeholders, because only with everyone working together will we get the best research done and the best results for our communities.