Growth partitioning three years following structural pruning of Quercus virginiana

One codominant stem on each of 48 similar Quercus virginiana Highrise® trees was pruned to evaluate impact of pruning severity on growth suppression and partitioning. Targeted pruning severity (0, 25, 50 or 75% foliage and subtending branches removed) based on visual estimates of two people correlated well (r² = 0.87) with the ratio stem cross-sectional area removed: cross-sectional area at base of the pruned codominant stem. Pruning reduced cross-sectional area growth on codominant stems compared to the leader stem that was not pruned, especially during the first 12 months following pruning. Increased pruning severity reduced cross-sectional area growth on the pruned stem in proportion to amount of foliage removed. In each of three years following pruning, cross-sectional area of the unpruned leader stem increased more on trees receiving targeted pruning severities of 25% or 50% than trees pruned with the 75% severity or trees not pruned. Shift in growth from the pruned to unpruned portion of the tree reduced diameter ratio between the two stems, which should make the union stronger. Diameter ratio changed most for the 75% pruning severity.