Modern state of natural populations of Medicago cancellata Bieb. rare species in the Bashkortostan Republic
The aim of this study was to investigate the ontogenetic structure, morphometric parameters and to identify the vital structure of M. cancellata cenopopulations in the Bashkortostan Republic. In 2015, we examined the state of five M. cancellata cenopopulations in the region of the South Urals in petrophyte steppes of the Bashkir Cis-Urals: CP 1 - Yaryshtau city (54,150555°N, 55,096944°E), CP 2 - Alyshevo village (54,034370°N, 55,070412°E), CP 3 - Susaktau city (52,583333°N, 55,983888°E), CP 4 - Pikarskaya city (55,026251°N, 56,226310°E), CP 5 - Satyrtau city (56,251933°N, 56,252403°E). To study the demographic structure and the density of cenopopulations in each transect we created 25 sample plots of 1 m2. We determined the leading population characteristics, such as general and effective density of individuals and developmental structure. The study of morphometry under natural conditions was carried out on 25 average generative individuals. During a discriminate analysis we calculated phenotypic distance expressed by the Mahalanobis distance. The studies revealed that the predominant type of vegetation is Agropyron pectinatum grassland petrophyte steppe. Mainly, cenopopulations occupy top or upper portions of steep (30-40°) southern slopes, occasionally of eastern exposure. These are usually eroded rocky slopes, with low rates of vegetation cover; erosion is related both to natural causes (water and wind erosion) and anthropogenic factors (grazing). The total density of M. cancellata cenopopulations varies from 2.2 to 5.8 ind./m2, the effective density - 2.0-3.8 ind./m2. All studied M. cancellata populations are normal and non-complete; the peak, on the average, is generative individuals. According to the classification of "delta-omega", four cenopopulations are mature and one is aging. The recovery and aging index in all cenopopulations is close or equal to zero. The results of the study of morphometric parameters showed that considering most indicators of both vegetative and generative spheres the cenopopulation on Susaktau mountain is leading, where the predominant type of vegetation is Agropyron pectinatum grassland petrophyte steppe; minimum values for all parameters are observed in populations near Alyshevo village, with the predominant type of vegetation - Stipa korshinskyi-Salvia nutans petrophyte steppe. The greatest variability is typical of the following parameters: the number of generative shoots (19.3-40.2%), and the number of leaves (20.1-38.6%) and the flowers in the inflorescence (24.3-37.2%). Other parameters have a normal degree of variability (6.0-37.7%). We used the discriminate analysis method to set Mahalanobis squared distances among cenopopulations. The maximum distance is among cenopopulations which are situated on Yaryshtau-Susaktau mountains and Yaryshtau - Pikarskaya mountains (58.18; 66.82), the lowest is between Yaryshtau mountain -Alyshevo village and Pikarskaya - Satyrtau mountains (13.95; 11.39). To estimate the vitality spectrum of cenopopulations we singled out a determining set of characteristics: the number of leaves on one generative stem and the number of flowers per stem. The analysis showed that two populations are thriving (Q - 0.38-0.5) and three are depressive (Q - 0.04-0.30). The state of the studied populations is relatively satisfactory. To enhance the protection of species, a constant monitoring of the state of populations is needed. For all the main indicators, the most favorable conditions for the growth of Medicago cancellata form in Kochia prostrate-Artemisia salsoloides steppes on Susaktau mountain reefs. Along with the already existing protected areas, it is recommended to create a nature monument "Yaryshtau Mountain" in Davlekanovo region of the Bashkortostan Republic.