Root Barriers and Windthrow Potential

Abstract

This study was developed to determine if commercially available ribbed barriers reduce or increase the stability of trees under severe lateral stress. Green ash ( Fraxinus pennsylvanica ) were planted in November 1996: 6 in surrounding-type tree root barriers and 6 without barriers. Half of each group was pulled over in July 1999 under dry (14% water) soil conditions and the other half was pulled over under saturated (33% water) soil conditions. The force required to pull the trees over was measured as was the wind resistance of the trees. Slightly more force was required to pull over the trees grown within root barriers than the control trees. The force required for the weakest tree, however, was far greater than that exerted by a 100-mph (160-kph) wind. The reason for the increased strength of the root barrier trees appeared to be the deeper root system.