Home – Home – Jornals – Flora and Vegetation of Asian Russia 2023 number 3

The purpose of this work is to summarize information about the distribution of the rare species of Oxytropis growing in the Republic of Uzbekistan to clarify their ranges, to start an inventory of their locations and to study the demographic structure of their coenotic populations. To assess the condition and conservation of rare plants, it is necessary to study their biological characteristics, as one of the primary tasks of the population ecology, the study of populations of rare, endangered and protected plant species is required for elaborating effective measures to maintain their stable existence. The structure of the habitats of 10 rare species of Oxytropis growing on the territory of the Republic of Uzbekistan was studied on the basis of herbarium samples and of a review of literary and electronic sources. Herbarium collections of rare species of Oxytropis date from 1924 to 1987, with only tenth of the collections made later than 2000. Such species as O. maidantalelsis, O. schachimardanica, O. tyttantha and O. vvedenskyi were not collected at all in the 21st century. Therefore, revision of the existing habitats and detailed evaluation of the status of rare and endemic species of Oxytropis is very relevant at the present time. As a result of the conducted studies, it was found that the studied species live in mountainous areas, at altitudes from 820 to 3400 m above sea level, on steep 20-35° rocky slopes of different exposures in phytocoenoses with low projective coverage from 15 to 50 %, while the projective coverage of Oxytropis is small and amounts to 1 % or less. The populations of the studied species are small (100-400 plants) and isolated. Data are presented indicating that most of the coenopopulations of the rare species of Oxytropis persistently have existed in their habitats for a long time. As a rule, these are populations that are protected on the territory of nature reserves and national parks or are located in hard-to-reach places. Those populations which are located outside protected areas are subjected to strong, uncontrolled grazing, up to their complete destruction. All the investigated coenopopulations (CP) of Oxytropis species are normal, definitive, the CP of O. fedtschenkoana and O. kamelinii are full-fledged, the other CP of the remaining studied species are incomplete. In incomplete cenopopulations, plants of the postgenerative period are most often absent, less often - those of the pregenerative period. The CP O. kamelinii, O. lasiocarpa, O. pseudoleptophysa and O. pseudorosea are with a left-sided ontogenetic spectrum (pregenerative and young generative individuals predominate), the CP O. fedtschenkoana are with a centered type of spectrum. In general, in the coenotic populations of Oxytropis, a high proportion of generative plants was noted - from 36.9 to 96.2 %. In all of those, with the exception of O. lasiocarpa CP (3.8 %), the percentage of individuals of the pregenerative period is high - from 32.9 to 60.5 %, indicating successful seed renewal in these coenopopulations. A large proportion of pregenerative plants makes it possible to predict successful replenishment of the generative fraction of the plants in the near future. The fraction of plants of the post-generative period in the CP is insignificant - up to 6.3 %, suggesting that the plants remain in the generative state for almost the entire life cycle. The rare species of Oxytropis of Uzbekistan are mountain species with a narrow-locality range and a narrow ecological amplitude, with a small number of populations within the range. The number of their populations is small, and the trends of its changes have not been established. The analysis of the state of coenotic populations has shown that overgrazing, leading to destruction of seedlings, juvenile and immature individuals, as well as to a decrease in the vitality and seed productivity of generative plants due to their partial or complete eating, is one of the main limiting factors. It can be concluded that all the species of Oxytropis studied by us are vulnerable due to the peculiarities of biology (exclusively seed reproduction), stenotopy, the small size of their populations and the decrease in their numbers as a result of the anthropogenic impact. An in-depth study of the biological features of rare species of Oxytropis of Uzbekistan, the state of coenotic populations, further inventory of known habitats and search for new ones are necessary. The main condition for the conservation of currently rare species, especially such species as O. pseudorosea and O. kamelinii, consists in organizing protection of all the populations and regular monitoring of their condition at the places of the most intense anthropogenic impact. The results obtained can be used in the next edition of the Red Book of the Republic of Uzbekistan and for organizing effective measures for protection of the species.