Photosynthetic apparatus efficiency of eight tree taxa as an indicator of their tolerance to urban environments

Urban trees, especially those growing in close proximity to roads, suffer from different kinds of stress. Most of roadside stress factors are impossible to be avoided therefore the selection of tolerant tree species andcultivars is of high importance. In our research we usedthe activity of photosystem II andchlorophyll relative content to monitor physiological state of 8 species andcultivars growing in urban environments in Warsaw. We comparedyoung trees growing 2–3 m away from the roadandothers growing minimum 8 meters away. The experiment allowed us to indicate the most tolerant taxa to roadside conditions: Gleditsia triacanthos, Pyrus calleryana ‘Chanticleer’, Platanus ×hispanica ‘Acerifolia’ and Acer campestre. We foundthat Quercus rubra is relatively tolerant. Tilia ×europaea ‘Pallida’, Tilia cordata ‘Greenspire’ and Ginkgo biloba should not be planted in harmful habitats.