TREE SWAY PERIOD—A POSSIBLE NEW PARAMETER FOR CROWN CLASSIFICATION AND STAND COMPETITION

Abstract

The natural sway periods of red pine (Pinus resinosa Ait.) and some white pine (Pinus strobus L.) trees were measured with a stop watch in four plantations and one native stand. This new parameter showed fair correlation with the ratio diameter/height; deviations therefrom were thought to be due largely to the variable mass and height of the crown. The crowns were pruned from six large red pines and the sway periods of their pruned boles were observed. "Crown moment" was postulated as a more all-inclusive index than either crown density or crown class alone. Other possible factors affecting tree sway period were discussed, although the relative importance of each remains to be investigated. Sway period frequency curves for each stand suggested that the mean sway period of a stand increases with age and with increasing competition.