Impact of heavy pruning on development and photosynthesis of Tilia cordata Mill. trees

Tree pruning is carried out to reduce conflict with infrastructure, buildings, and any other human activity. However, heavy pruning may result in a diminished tree crown capacity for sugar production and exposure to fungal infection. This risk leads to a decrease in tree stability or vigour. In this work, we analysed the effect of heavy pruning of roadside trees on the photosynthetic performance process compared to neighbouring unpruned trees. Four years of tree crown growth was studied by terrestrial imaging. Tree vitality (Roloff's classification) and risk (Visual Tree Assessment) were evaluated. Over-pruned trees showed intensified photosynthetic efficiency during the growing season following pruning. Particularly ET0/TR0 and PIABS tended to increase in pruned trees while higher Fv/Fm was noted only in late October, suggesting delayed leaf senescence. After four years, pruned trees rebuilt their crowns, however not in their entirety. Results obtained from biometric, vitality, and risk assessment showed high differentiation in pruned tree crown recovery. Our results revealed that despite the intensified efforts of trees to recover from wounding effects, severe pruning evokes dieback occurrence and a higher risk of failure in mature trees.