Off-campus UMass Amherst users: To download campus access theses, please use the following link to log into our proxy server with your UMass Amherst user name and password.

Non-UMass Amherst users: Please talk to your librarian about requesting this thesis through interlibrary loan.

Theses that have an embargo placed on them will not be available to anyone until the embargo expires.

Access Type

Open Access

Document Type


Degree Program

Environmental Conservation

Degree Type

Master of Science (M.S.)

Year Degree Awarded


Month Degree Awarded



Damping, Oscillation, Trees, Dynamics, Co-Dominant


Natural frequency and damping ratio were measured for ten forest grown northern red oak trees with co-dominant trunks. Steels support cables were installed in the canopies of five of the sample trees prior to measurement. Free vibration testing was performed during periods when leaves were and were not present. An accelerometer mounted at the base of the co-dominant union measured the acceleration time history during the free vibration testing. Natural frequency was determined from the acceleration time history using power spectral density analysis. Damping ratios were calculated from the power spectral density plots using the half power bandwidth method.

Trees with steel support cables had higher natural frequencies than trees without steel support cables. Sample trees had higher natural frequencies in the leaf off condition than the leaf on condition. The increase in natural frequency associated with the steel support cable was less pronounced in the leaf on condition. There was no difference between the damping ratios of cabled and non-cabled trees. Trees in the leaf on condition had significantly higher damping ratios than trees in the leaf off condition.


First Advisor

Brian C.P. Kane