Variability in seasonal development of

The article describes the results of long-term biomonitoring of habitat quality based on the phenology of the Tilia cordata tree species from the city of Yoshkar-Ola, Russia. Phenorhythms have been studied in trees of various ontogenetic states. The phenological observations took into account 13 phases of development of the vegetative and generative spheres of T. cordata. In urban conditions, the spring biorhythmological processes in T. cordata occur 3-10 days earlier than in natural conditions, while the autumn processes can begin even more significantly earlier, by 2-3 weeks. Its possible to distinguish age-related phenorhythmic groups with different rates of seasonal development in the studied local populations of T. cordata: 1 - with early onset and prolonged vegetation – trees of the generative period of ontogenesis of middle and old age, 2 - with late onset and rapid vegetation – trees of the generative period of ontogenesis of young age. In an anthropogenically transformed ecosystem, the individual rate of seasonal development of T. cordata can accelerate or slow down, which is more common for g2 and g3 ontogenetic states. Trends in the timing of the onset of phenophases at the research object in the forest park and in urban plantings in Yoshkar-Ola generally indicate the climate warming trend: earlier spring and later autumn dates are established, and the duration of the growing season is increasing. The multivariate phenorhythms of ontogenesis contribute to the growth of biodiversity and the adaptation of local populations of T.cordata to adverse environmental factors, including climatic stresses and pollution.