Effects of Root Cutting on Physiological Responses of Tilia cordata and Acer platanoides Four Years After Intervention in Urban Parks

Urban construction often involves root cutting, which can affect tree stability and disrupt physiological processes. However, studies assessing the impacts of root cutting on urban trees remain limited. Our objective was to quantify the physiological responses of mature trees four years after root cutting of increasing severity, applied on one side of the tree or on two perpendicular sides. Stomatal conductance, net photosynthesis at the light saturation point and predawn leaf water potential were measured in Tilia cordata Mill. (n = 26) and Acer platanoides L. (n = 26), across six municipal parks in Québec City (Canada). No significant differences in stomatal conductance were observed among treatments. A general effect of root cutting on photosynthesis was detected, but no significant decline was observed with trench severity. Moreover, the predawn leaf water potential values suggest that trees maintained adequate overnight rehydration despite root disturbances. These results suggest the presence of compensatory root mechanisms and physiological resilience in both species under urban park conditions, even when trenching was performed closer to the trunk than the recommended distances, based on the International Society of Arboriculture Standards. This study can provide municipalities with valuable information to support root trench planning, assess associated risks, and implement effective measures to preserve mature trees in urban parks.