Reduction pruning of main tree stems is commonly performed in the maintenance of an electricity distribution network to encourage the growth of scaffold limbs away from the wires. Understanding both the initiation and growth of epicormic branch after reduction pruning interventions, as well as the area of discolored wood at the cutting point are important for optimizing the pruning cycle and maintaining safe trees. In this study, we investigated post-pruning traumatic responses in relation to tree vitality before pruning in 116 hackberries (Celtis occidentalis L.) and 86 green ash (Fraxinus pennsylvanica Marsh.) growing in a controlled environment of a nursery. Four years before pruning, each tree of both species was assigned a degree of damage commonly occurring in urban areas, including root injury, defoliation, and stem injury, for a total of 18 treatment combinations arranged in a random block design. In both species, trees that had lower vitality prior to pruning had a reduced number, height, and volume of the epicormic branches at the cutting point two years after main stem pruning. Interestingly and contrary to expectations, a positive relationship was found between the area of discolored wood at the cutting point and tree vitality prior to pruning. However, below a vitality threshold, the area of wood discoloration was exacerbated by crown dieback and retrenchment. Celtis showed a less efficient ability to compartmentalize and produced fewer epicormic branches compared to Fraxinus, and epicormic branches were of reduced height and volume when low growth was observed. From a management perspective, although both species can survive after several damage events and after reduction of the main stem, the results suggest to conduct an assessment of tree vitality before pruning to identify trees with lower vitality and better predict the return pruning time.

主要树干的减少修剪通常在配电网络的维护中进行，以促进脚手架枝条远离电线的生长。了解减少修剪干预后表皮枝的萌生和生长，以及切割点变色木材的面积，对于优化修剪周期和维护树木安全非常重要。在这项研究中，我们调查了 116 棵朴树（Celtis occidentalis L.）和 86棵绿灰（Fraxinus pennsylvanicaMarsh.) 在受控的苗圃环境中生长。修剪前四年，两种树种的每棵树都被指定了城市地区常见的损害程度，包括根损伤、落叶和茎损伤，总共 18 个处理组合以随机块设计排列。在这两个物种中，修剪前生命力较低的树木在主茎修剪两年后切割点处的上皮枝的数量、高度和体积均减少。有趣且出乎意料的是，在修剪前发现切割点变色木材面积与树木活力之间存在正相关关系。然而，在活力阈值以下，木材变色区域因树冠枯死和收缩而加剧。凯尔特人与水曲柳相比，表现出较低的划分和产生较少的表皮分支的效率较低的能力，并且当观察到低生长时，表皮分支的高度和体积降低。从管理的角度来看，虽然这两个物种在多次破坏事件和主干减少后都可以存活，但结果建议在修剪前进行树木活力评估，以识别活力较低的树木并更好地预测回归修剪时间。