Coenopopulations of Isopyrum thalictroides L. in the M. M. Gryshko National Botanical Garden of the NAS of Ukraine

The article presents the results of a study of coenopopulations of European relict species, regionally rare ornamental spring ephemeroid Isopyrum thalictroides L. in the collection “Rare plants of the flora of Ukraine” and botanical-geographical areas “Altai and Western Siberia” and “Steppes of Ukraine” of M. M. Gryshko National Botanical Garden of the National Academy of Sciences of Ukraine (NBG). The origin of I. thalictroides in the areas of the NBG is different. On the plot “Rare plants of the flora of Ukraine” I. thalictroides is an introduced species, but in the areas “Altai and Western Siberia” and “Steppes of Ukraine” it is ergasiophygophyte. In the areas of NBG I. thalictroides shows a tendency to expand the territory, penetrates into forest (“Altai and Western Siberia”) and meadow-steppe (“Steppes of Ukraine”) cultural phytocoenoses, where it forms spontaneous coenopopulations. The conditions of habitats and sizes of coenopopulations of I. thalictroides differ in the areas of NBG: the largest is in the area “Rare plants of flora of Ukraine” (2.6 × 2.6 m), medium in “Altai and Western Siberia” (sizes of loci 1.3 × 1.3 m, 0.4 × 0.4 m and 0.1 × 0.1 m), the smallest in “Steppes of Ukraine” (0.3 × 0.3 m). Rhythms of growth and development of I. thalictroides in the conditions of Kyiv quite correspond to seasonal fluctuations of temperatures. The earliest flowering of I. thalictroides was observed in the areas of the NBG in the first half of April 2020, the latest in the second half of April in 2021–2022; flowering period in the beginning of fruiting in all areas coincided. Coenotic conditions of I. thalictroides habitats in the composition of artificially formed vegetation in the NBG and in nature differ. In the NBG areas, the species grows together with introduced, native and alien plant species and shows significant ecological and coenotic plasticity. The age spectra of all coenopopulations of I. thalictroides on the NBG areas are left-handed. The total percentage of shoots of the pregenerative period of ontogenesis (juvenile, immature, virginіle) is very high (88.98–93.62 %). The highest values are for virginile shoots (71.78–82.98 %), which may be due to the predominance of vegetative propagation over seed. The spatial distribution of shoots in coenopopulations of I. thalictroides is group, which may be due to a combination of barochoria and vegetative propagation. The number of shoots in coenopopulations of I. thalictroides in different parts of the NBG differs significantly: the largest is in the area “Rare plants of flora of Ukraine” (3562 shoots), medium in “Altai and Western Siberia” (1017 shoots), the smallest in “Steppes of Ukraine” (47 shoots). In contrast, the average density of shoots in all coenopopulations of I. thalictroides is high, uniform and is 522–546 different age shoots per 1 m2. The dependence of the number of flowers and/or fruits оn generative shoots from the height of the shoots was not detected. A study of the growth and development of I. thalictroides in NBG areas has shown that the formation of coenopopulations, both introductory and spontaneous, is an effective and promising method of conservation and protection of this species ex situ.