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.

Drag relationships for full-grown Scots pine trees

“…The results for the drag load on the small branches of cedar pine (Pinus sibirica Du Tour) show a linear dependence on velocity (Orlov and Shrager 2011). In the article by Smiley et al (2000), wind loads on green trees were measured at various wind speeds. They reported that the drag load showed a linear increase with the wind speed as well.…”