Tree species phenology at northern and southern borders of their habitat under conditions of introduction stress

Decorative types and varieties of trees and shrubs have long been widely used in the practice of gardening and landscape construction. Significant enrichment of the range of urban green spaces is possible due to the introduction of introduced plants. The arboretum garden is studying the possibility of growing non-district rocks in specific soil and climate conditions and selecting promising species for gardening, which will create valuable introduced objects. The processes of plant growth and phenological development are analyzed in detail. In this paper, tree and shrub species that grow on the Northern and southern borders of their introduction within the Russian Federation are selected. Observations were made in dendrological gardens in the cities of Arkhangelsk and Sochi. The phenological dates of seasonal development of these species are established and recommendations are given for the use of the studied introduced species in the urban greening system. It is established, for example, that Hungarian lilac grows successfully and bears fruit on the Northern border of introduction and has a winter hardiness score of I, while in subtropical climate this species, although it forms generative organs, has a depressed state. Western thuja in the conditions of Arkhangelsk does not bloom and does not bear fruit, it dies out in severe winters. On the southern border of its introduction, it is widely used in the urban greening system and in topiary art. The correct selection of species on the introduction site will allow you create a highly decorative, aesthetically charming, recreational-attractive, health-improving plantings.