Quality assessment of urban trees using growth visual and chlorophyll fluorescence indicators

Urbanised landscape represents composed structures of technical and biotic elements where social and economy activities create living space for human society but with strongly changed environment. To dominant characters belong climate changes with increased air temperature, drought and emission load, which has developed wide spectrum of stress factors influencing the urban vegetation. For the assessment of plant growth and adaptation response, we have used Sycamore maple (Acer pseudoplatanus L.) as study model woody plant. In the framework of visual characters, we assessed the following indicators: (a) assimilation organs (leaf necrosis); (b) crown quality (degree of foliage and degree of dead tree crown); (c) trunk and branch quality (mechanical damage, incidence of wood destroying fungus and trunk cavities and callus healing of trunk wounds). Each indicator was assessed in five-point scale, and in the end, the common index of quality was calculated. The quality index achieved 9.33 points in the first and 10.33 in the second evaluation periods in the Nitra city and 2.66 at the both assessed periods in the comparable rural park. In the group of physiological indicators, chlorophyll a fluorescence marker and its Fv/Fm parameter were used. Within three repeating assessment during growing season (June, August and September), the average values reached Fv/Fm = 0.814 in the city and Fv/Fm = 0.829 in rural park. The results confirmed statistical significances between loaded city conditions and relatively clean rural locality. Used markers have shown as appropriate tools for growth response measurements of street trees in a changed urban environment