Ecological and biological characteristics of Hemerocallis minor (Hemerocallidaceae) species, rare for Yakutia

Changes in natural ecosystems affected not only the central regions of Russia, but also the regions where extractive industry is developed. The vegetative communities of Central and South Yakutia are experiencing great strain, but especially in the valley of the Lena river. Many species of rare plants are represented by peripheral populations in the territory of Yakutia. Programs for the conservation and restoration of biological diversity should take into account the genetic diversity of such isolated populations. Hemerocallis minor is an Asian species that is common in southern Siberia. The northern boundary of the range of this species passes in the valley of the middle reaches of the Lena river (63° NS). Populations of H. minor are at a great distance from other populations in Siberia and they are extremely rare in Yakutia. All known habitats of the species are not protected by the Specially Protected Natural Areas networks. The aim of the research was to study the peripheral populations of H. minor, their phytocoenosis, ontogeny, age structure and density of the coenopopulations, as well as the introduction possibilities of the species. The study was conducted in its natural habitats in Olyekminsky District of Southwest Yakutia. We investigated two locations of coenopopulations of H. minor. We examined the abundance, density and ratio of individuals of different age groups in the population to reveal the structure of H. minor population. H. minor ontogeny is incomplete and includes 3 periods: latent, regenerative and generative. The postgenerative period is not expressed. Ontogeny occurs faster in culture conditions. The main part of individuals reaches the generative period in the third year of life. The first location is a floodplain meadow near Abaga village. The meadow is used for traditional land use. The vegetation is composed of a dense herbaceous layer of tall forbs and graminoids. Species include 37 phanerogams plants. The population of H. minor occupies 1120 m². The second population of this species is found in pebbly shore of the Lena river near the mouth of the Bol'shoy Sintyah river. The area of this population is small, only 10 m². Except H. minor, other species do not grow here. In each location, we recorded and classified all individuals into life cycle stage: juvenile, immature, vegetative and flowering individuals. The total number of flowering adults - 17 and vegetative - 50 individuals in the first population. The ratio of age state shows that the process of renewing is not annual and is mainly limited by human activities. The proportion of young plants (juvenile, immature, vegetative individuals) in the second population was higher than in the first. The total number of flowering adults -13, vegetative - 13, immature - 32, and juvenile - 4 individuals. Thus, the studied populations of H. minor are normal and incomplete. Both populations are young according to the criterion of the absolute maximum. The results of the classification of "Delta-omega" indicate that the first population is close to maturing. The second population is very young and the proportion of young individuals will grow in the absence of limiting factors. This population can stay young for quite a long time. In nature, the populations themselves are renewed by seeds only, which is often impossible due to anthropogenic impact. These results demonstrate the paucity and vulnerability of this coenopopulations. H. minor responds well to the conditions of culture. Plants annually and abundantly bear fruit, forming a numerous viable self-sowing, the conditions of culture contribute to the increase in the morphological characteristics of the species. The introductory populations of H. minor can serve as a reserve fund for possible reintroduction activities for restoring the number of disturbed natural coenopopulations of this rare species. The article contains 1 Figure, 2 Tables, 28 References.

Keywords

Authors

References