Effect of Tree Size, Root Pruning, and Production Method
on Root Growth and Lateral Stability of Quercus virginiana
Edward F. Gilman and Forrest J. Masters
Abstract: This research aimed to evaluate impact of slicing the outer edge of container root balls, initial tree size at planting, and root ball composition on post-planting tree stability in a simulated wind storm. One-hundred twenty Cathedral OakŪ live oak were planted in March 2005. Thirty field-grown trees were transplanted, and 60 trees of similar size were planted from 170 L containers. Root ball sides on 30 containers were sliced prior to planting. Thirty smaller trees from 57 L containers were planted without slicing. Trees were pulled with an electric winch, and blown with a hurricane simulator in 2007. Slicing the root ball had no impact on root growth, bending moment, or bending stress. More bending stress was required to pull field-grown trees than trees planted from containers of either size. Growing trees in containers for three years prior to landscape planting changed root morphology compared to field-grown trees, which corresponded to reduced stability. Trees planted from small containers were as stable as those from larger containers. Root cross-sectional area windward correlated the most with bending stress required to tilt trees with a winch and cable. Bending moment scaled to the 3.4 power of trunk diameter.
Keywords: Bending Stress; Container-Grown; Field-Grown; Root Cross-Sectional Area; Root Diameter; Root Number; Saturated Soil; Trunk