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Wind & Trees

Healthy trees in open locations are seldom damaged by storms, even when exposed to high winds. Trees in these conditions become resilient to wind and weather conditions, including ice, snow and rain, and withstand storm damage with plenty of room to grow and sway.

Conversely, trees growing in unmanaged forests and along roadsides are more susceptible to storm damage due to competition for space, sunlight and water. In these cases, crowded conditions create susceptibility to tree damage on blue sky and stormy days.

To understand tree behavior for safety and proactive tree trimming benefits, UConn forest researchers specializing in tree sway mechanics are continuously monitoring the motions of forest-grown trees.

Field experiments are monitoring trees before and after removal of specific trees to track progress toward becoming wind-firm. The trees, in three Connecticut locations, are wearing sensors to capture tree sway at a rate of 10 times per second, 24 hours a day, in all wind speeds. This research is valuable in our Mapping Tree Risk initiative.

The research will identify why some trees and limbs break, while others bend with the motion of the wind. This research will provide guidance to Roadside Tree and Forest Management and utility tree trimming best practices.

did-you-know-trees

  • Connecticut ranks thirteenth in the nation in terms of percent forest cover and fourth in terms of population density
  • 55 percent of Connecticut is currently covered by forest
  • Trees in wetlands, rocky or shallow soils have shallow roots and are more susceptible to uprooting.
  • Trees grown in unmanaged forest conditions tend to be tall and slender and susceptible to damage when exposed to wind.
  • Trees in a forest are sheltered by neighboring trees and typically have less wind exposure than open grown trees.
  • Trees along a forest edge are unsheltered and have high potential for wind exposure.
  • Trees along a new or recently trimmed forest edge may be less stable until they adjust to the increased wind exposure.
  • Trees along a forest edge grow toward the open space and so tend to have severe leans and lopsided crowns with reduced stability.
  • Compared to trees that are grown in crowded conditions, trees that have room will grow larger trunks and symmetrical crowns which improves stability and wind resistance.
  • The form of a tree can affect its stability – leans or lopsided crowns make a tree less storm-resistant.

Goals & Project Updates

 The purpose of this research is to provide guidance to forest management activities that are intended to improve the stability of forests near utility infrastructure. The goals for this project are to:

  • Determine how tree stability is affected immediately after forest management (e.g. thinning).
  • Monitor how tree stability changes over a several year period after forest management with trees of various species and ages.

Three study sites have been established in Storrs, Orange and Torrington, Connecticut. Sensors have continuously monitored the sway of nearly 40 trees across these sites. The status of each site is as follows:

  • Storrs site: monitored since 2012 with forest thinning treatment in 2013
  • Orange site: monitored since 2014 with forest treatment in March 2016
  • Torrington site: monitored since 2014 with forest treatment scheduled for summer 2016

Preliminary analysis of the Storrs field site indicates that forest management substantially increased tree bending.

Leaf-on deciduous trees tend to lack a distinct sway frequency, which may suggest that trees are unlikely to resonate with the wind.

  • image026

    Weather station used to monitor wind speed and direction and air temperature.

  • image029

    Map showing tree crowns (green circles) before and after forest thinning at a study site in Storrs, Connecticut.

  • image027

    The contour map shows the frequency at which the tree stem occurs at a given location. The maximum displacement of the stem, from its resting location (star), for a given wind speed can indicate tree wind-firmness.


Team Members

John Volin, Professor and Head, Department of Natural Resources and the Environment, University of Connecticut.

Jason Parent, Assistant Research Professor, Department of Natural Resources and the Environment, University of Connecticut.

David Miller, Professor Emeritus, Department of Natural Resources and the Environment, University of Connecticut.

Amanda Bunce, Graduate Student, Department of Natural Resources and the Environment, University of Connecticut

Thomas Worthley, Associate Extension Professor, Department of Extension, University of Connecticut.

Mark Rudnicki, Department of Forest Resources, Michigan Technological University

Jenna Klinck, Graduate Student, Department of Natural Resources and the Environment, University of Connecticut

 

Contact Information

For more information, please contact Jason Parent (jason.parent@uconn.edu)

Members of the media, please contact Center Manager Dave Wanik (dave.wanik@uconn.edu) directly.

 

Eversource Energy Center  | Address: 261 Glenbrook Road, Unit 3276, Storrs, CT 06269-3276 | E-Mail: eversourceenergycenter@uconn.edu