SPONTANEOUS POPULATIONS OF TAXUS TYPES (TAXACEAE) IN SYRETS ARBORETUM

The article presents the data on the status and structure of the spontaneous heterogeneous population of two species of the genus Taxus (Taxaceae), T. baccata and T. cuspidata, in the Syrets Arboretum of national importance (Kyiv). This population was formed as a result of spontaneous seed reproduction of cultured in the arboretum of adult specimens of two species of yew. The author describes the quantitative composition of individuals of the genus Taxus of seed origin and the conditions of their habitats as part of various types of plantings in Syrets Arboretum. The main morphometric indices of the yew individuals of seed origin were studied, namely their height and diameter of the stem. In general, on the territory of park plantations of the Syrets Arboretum and beyond it, 99 virginile and generative individuals of the genus Taxus (5 or more years) were found. In addition, on several plots more than 100 young individuals (1–4 years) were recorded. The spontaneous population of the yew in the Syrets Arboretum has high density and left-handed age spectrum and relates to young populations of normal type. Most of the generative individuals of the seed origin were identified. It was found that the ratio of individuals T. baccata and T. cuspidata in this population is about 2 : 1. The intensity of the growth and development of the yew trees of the seed origin in the Syrets Arboretum is similar to the characteristics of the populations in natural environment but is less than in the culture. The transition of the young yew individuals on the generative stage of development in the conditions of Syrets Arboretum requires 12–19 years. The best conditions for the sprouting of the yew seed and the development of young individuals were noted in plots with medium sunlight, lack of shrubs, sparse grass (without dense cover), and a thick layer of leaves on the soil surface. In general, preservation of the ex situ rare species of the genus Taxus in the Syrets Arboretum is currently provided in the level of the formation of normal populations.