Antioxidant Responses and Adaptation Mechanisms of Tilia tomentosa Moench, Fraxinus excelsior L. and Pinus nigra J. F. Arnold towards Urban Air Pollution

The aim of this study was to assess the antioxidant response towards urban air pollution of three widespread ornamental species—Tilia tomentosa, Fraxinus excelsior and Pinus nigra. Saplings were planted in four urban plots with different anthropogenic impacts, and periodic observations were performed on their development. Three types of biochemical markers, representing plant responses by three different mechanisms, were analyzed: photosynthetic pigments, free proline and guaiacol peroxidase activity. Our study confirmed that plant responses and adaptation to the environment are complex biological processes including physiological and biochemical changes. As a whole, these experiments revealed that the studied trees react by specific mechanisms towards urban air pollution, and antioxidant responses are significantly correlated with the enhancement of traffic (p < 0.05). Fraxinus excelsior was assessed as being very suitable for urban landscaping due to the significant tolerance to environmentally stressful conditions. Tilia tomentosa was also evaluated as a suitable ornamental species as it demonstrated good development in the urban environment. Pinus nigra was proven as more sensitive to the urban air pollution versus the other two studied trees. These findings could be very useful as a scientific basis for the landscaping practice in terms of the sustainable development and management of urban forestry.