Analysis of street plantations vitality after the rejuvenation pruning (on the example of Dnipro city)

The influence of pruning of the crown on the state of five tree species has been studied (Robinia pseudoacacia L., Ulmus pumila L., Gleditsia triacanthos L., Acer pseudoplatanus L. and Populus bolleana Lauch.). The trees were pruning at a height of 8 meters, leaving only the trunk and lower branches. Control plants were not pruned. All plants are growing on the boulevard near the highway with high traffic. It was found that among the rejuvenated trees there are more both healthy plants and severely damaged ones. Dead plants appeared among species such as G. triacanthos, A. pseudoplatanus, and R. pseudoacacia also. The best vital state was found in P. bolleana and U. pumila. Plants after crowning have more water content in leaves. U. pumila and G. triacanthos have the greatest difference in water content between the two variants. The intensity of transpiration in pruning plants P. bolleana and G. triacanthos is 2 times higher, and in U. pumila – by 20 %. In A. pseudoplatanus and R. pseudoacacia, there is no difference in this indicator between the variants. Pruned plants have a lower water-holding capacity by an average of 30 % compared to control (except for P. bolleana, in which the difference between the variants is insignificant). The content of green pigments is higher than in the control samples in the leaves of the rejuvenated plants. The exception is R. pseudoacacia, which has a reverse reaction. Thus, the intensification of the processes of water exchange and the pigment system does not occur in all species to the same extent. It is most pronounced in U. pumila and G. triacanthos. The activity of photosynthesis and water exchange in both variants differs insignificantly at P. bolleana. R. pseudoacacia have deterioration in all parameters. This probably explains the poor condition of pruned trees of this species.