Service tree (Sorbus domestica L.) and wild pear (Pyrus pyraster L. Burgsd.) are lightdemanding species tolerant to water deficiency during the growing season (Brutsch & Rotach, 1993; Rittershoffer, 1998; Wilhelm, 1998; Paganova, 2003a, 2008; Paganova & Jurekova, 2012). According to the ecology background, these woody plants are potentially suitable for extreme conditions of urban and landscape environment.
These woody plants are part of the original flora in Slovakia. For both taxa large seasonal and phenotypic variability has been documented (Pagan & Paganova, 2000; Paganova, 2003b) that represent a good basis for targeted selection of genotypes with the qualities required for landscape planning and design. Species with high phenotypic plasticity it is assumed survive better on stands with changing environmental conditions. They have higher adaptability to changes by modifications of their functions and structures which increases the probability of their survival and reproduction. However, environmental conditions on stands affected by anthropogenic activities change too fast for manifestation of the evolutionary mechanisms of the plant adaptation (Sultan, 2004), so non-hereditary changes of plants – acclimations – take place. This is why detailed evaluation of the adaptability and phenotypic plasticity of non-traditional or rare woody plants is an essential tool when assessing their wider utilization in the urban landscape.