Managed Development of Tree Roots: I. Ultra-Deep Rootball and Root Barrier Effects on European Hackberry

Four-year-old seedlings of European hackberry (Celtis australis) with rootballs 35 cm (14 in.) and 70 cm (28 in.) deep, were field planted in northern California in April 1986 to compare root development as affected by rootball depth and a casing that fit snugly around the rootball to function as a root barrier. Three growing seasons later, the roots of each tree were excavated to a 32-cm depth in an area within approximately 1 m radius from the trunk and the dry weights of these roots determined. Root weight was significantly different between the two root barrier treatments but not between the two rootball depths.