The effects of wind on tree sway and stability

2005 | Dr. Mark Rudnicki

Tree failure and crown damage from wind and ice storms cause loss of life and extensive property damage annually. A mechanistic understanding of how trees sway in the wind is critical for the development of effective management strategies with deciduous species being particularly complex and understudied. To quantify how an individual tree’s branches act individually and in concert to dissipate wind energies, we measured and reconstructed the sway of individual branches using three dimensional motion capture technology of mature trees in situ. Sway measures before and after treatments of branch motion restraint and pruning revealed how drag and mass damping affect the whole tree displacement and stability. The sway data from treatments of sugar maple, white ash, white pine, and red oak were used to construct and validate the dynamic sway model. In accordance with mechanical beam theory, branch dimensional parameters significantly influenced sway period and overall longer branches had greater sway periods. Comparisons of leaf-on and leaf-off trials demonstrated that leaf removal resulted in decreases to both damping ratio and sway period. Leaf removal had greater effect on damping ratio than sway period. The unexpected uniformity in behavior across species illustrates the complexities of tree biomechanics and warrants the need for additional research in deciduous sway dynamics. Calculation of whole tree sway values for other species will further the application of these results.

Year: 2005

Funding Duration: 3-5 years

Grant Program: Hyland Johns

Grant Title: The Effects of Wind on Tree Sway and Stability

Researcher: Mark Rudnicki

Key words: wind; crown sway; tree stability

Peer Reviewed Publications from Grant:

  • Burns, Daniel P. (2006) Branch Sway Dynamics of Four Tree Species from Eastern Hardwood Forests. Masters Thesis. University of Connecticut. 150pp.
  • Rudnicki, Mark and Burns D.P. (2006) Branch sway period of 4 tree species using 3-D motion tracking. Proceedings of the Fifth Plant Biomechanics Conference, STFI- Packforsk, Stockholm, Sweden 25-30.

General Audience/Trade Publications: none

Presentations: none

For more information on this project, contact the researcher via TREE Fund at