Effects of Pruning Dose and Type on Trunk Movement in Tropical Storm Winds

Abstract

We built a machine with a propeller capable of generating 33.5 m/s (75 mph) winds to determine the influence of pruning dose and American National Standards Institute A300 pruning type on trunk movement of Quercus virginiana ‘QVTIA’ PP #11219, Highrise® at various wind speeds. Trunk movement was regressed against wind speeds and pruning doses for each tree tested. Increasing wind speed increased trunk movement, and the magnitude of the increase depended on pruning dose and pruning type. Increasing pruning dose reduced trunk movement and the magnitude of the reduction was greater at higher wind speeds. The predicted trunk movement of thinned trees was statistically greater than movement of structurally pruned, raised, and lion’s tailed trees at wind speeds of 20.1 m/s (45 mph) and was greater than all pruning types at 26.8 m/s (60 mph). There was no difference in movement among reduced, raised, structurally pruned, and lion’s tailed trees; and there were no statistical differences in trunk movement among pruning types at the lower wind speeds. We found that thinning the outer edge of the crown was one of the least effective pruning types for reducing trunk movement in wind.