Results of the introduction of tree plants into South Uzbekistan from the Circumboreal floristic region

215 species, 4 forms and 5 hybrids grow in arboretums, parks and urban plantings of Southern Uzbekistan– a total of 224 taxa of woody introduced species, representing 113 genera from 52 families. Introduced plants came from 8floristic regions of the earth. The Circumboreal floristic area is home to 54 introduced species, of which 24 are found onlyin this area. They are originally from 10 provinces of the area. The range of 16 species lies in the boundaries of Irano-Turanregion, of 4 – in East Asian, of 3 – in the Mediterranean, of 2 species – in the Irano-Turan and Mediterranean regions. Thelargest number of species from the Circumboreal floristic region was introduced from the East European, Central European, West Siberian, Caucasian and Euxin provinces, where xeromesophytes, especially with increased drought resistance, aswell as mesothermophytes, which turned out to be more adapted in our conditions, prevail. Consequently, these provincescan serve as the main sources of introduction for southern Uzbekistan. Species from the North European, Central Siberian and Transbaikal provinces are less adapted. Representatives of these provinces are mesophytes and microthermophiles,and therefore they grow depressed and often do not bear fruits.