About some peculiarities of calcephyte flora of the Small-Amalatian depress (Northern Transbaikalia)

The article is devoted to the study of the calcephyte flora of the Small-Amalatian depress. The main objective of the study is to carry out floristic analysis of limestone outcrops. The calcephytic flora was analyzed on the longitudinal element, biomorphological, taxonomic and ecological analyzes were carried out.


Introduction
The calciferous outcrops in Malo-Amalatskaya Depression in the area of the cryophyte black hemlock forests are distinguished by original flora and vegetation that is due to the substrate peculiarities, geographical location and history of the studied territory [1]. The fragmentary calciferous outbursts in the territory of the East Siberia that have been formed for millions of years are particularly valuable to get to know the peculiarities of florogenesis of the North Asia, these are the localities where the relic elements of the Pleistocene cold ages have put down roots and preserved until now [2,3,4]. The calciferous flora of Malo-Amalatskaya Depression was studied by the staff members of the Botanics Department Buryat State University named after D. Banzarov.
The natural conditions of the studied area are characterized by ultracontinentality with the prevailing below-freezing average annual temperatures (from -2 ° to -6 °), short freezefree period (35-60 days), small amounts of precipitations primarily (up to 300 mm), falling in the second half of the summer and ubiquitous perpetually frozen ground. All these predetermine a high degree of peat formation in the studied territory in the background of the general relief evenness with interleaving low-rise steep slope ridges. By physical and geographical zoning, this territory belongs to the Transbaical mid-mountain-upland and Transbaical basins of the region, Vitimskaya upland province [5].
Malo-Amalatskaya Depression (pic. 1) -is one of the Meso-Cenozoic basins of the central part of the Vitimsky upland [6], with the bottom elevated to 1,000 m above-sea level. The north-west margins of the depression are formed by the calciferous rocks laying on schists and granites, with basalts occasionally occurring.

Results and discussion
The plant cover of all the studied territories is non-uniform. It is characterized by unevenness, low general projective cover (GPC) and low-rise species diversity.
Of woody plants, Larix dahurica Lawson is ubiquitous (hereinafter the names are given according to: "Abstract of the flora of Asian Russia") [7], on the town of Belaya (Bagdarin), a small-stemmed pine from Pinus sylvestris L. grows on a small contour in the upper part Belaya (Bagdakhali) is a crooked forest from Larix dahurica, one individual of the creeping Pinus sibirica Du Tour and three oppressed individuals of Picea obovata Ledeb were found. Aspen (Populus tremula L.) and birch (Betula pendulla Roth.) forests are noted in the middle and upper parts of the forested mountain of Izvestka. The calciferous flora of the studied territory is represented by 47 families, 105 genuses and 163 species. The angiosperms (92.02%) are dominating, and the cryptograms and gymnosperms are minimum (4.2 and 3.6%, respectively). 12 families are leading and make 66.26% of the flora. The flora formation, uniqueness and development reflect the smallspecies families that made almost a half of the entire flora -46.80%. The quantitative characteristics of the flora are given in Table 2. The spectrum of the leading families is headed by Asteraceae, Ranunculacea and Rosaceae that is characteristic for the flora of Baikal Siberia ( Table 3). The environmental analysis of the leading families' representatives showed the average out share of species of mesophytic and xerophytic ecology. This is explained by that the species acclimatized to the lacking humidity and severe solar radiation predominate at the steep calciferous slopes, and the increased humidity and bogginess that is aggravated by near occurrence of the perpetually frozen grounds are observed in the bottom. By comparing the spectrum, in general, with the flora of Amalat river basin [8], the high rank-performance of the Ericaceae, Orchidaceae and Pinaceae families can be observed. Such high concentration of the representatives of these families is characteristic for calcareous rock of the studied territory. The genus spectrum is headed by Salix (Table 2), these are mainly the forest species of willows but the species of the highland and mountainous general zone complex that are the obligate calciphytes are of particular interest: Salix saxatilis Turcz. ex Ledeb., S. fuscescens Andersson, S. nummularia Andersson. The top position is occupied by the Festuca genus where such endemic species as Festuca hubsugulica Krivot. and F. komarovii Krivot should be pointed out, at this, the interspecies were found out. This is shown by Table 4. If to exclude the group of forest species from the analysis (as the occurrence of the regional element of the vegetation in the studied territory), the species of the highland and mountainous general zone and steppe floristic complex are equally observed (approximate 27% each). The calciferous outcrops can be considered "as the bed in the historical process of phylocoenogenesis" for calciferous formations of the cryoarid periods of the Pleistocene. We have observed the listed species only on the carbonate substrates in the studied territory, with the most species wealth in Bagdakhali stow [9].

Conclusions
Therefore, the flora analysis showed that the outcrops perform the function of refuges of the Pleistocene relics in drier and colder localities. The equal share of the Arctic-Alpine and steppe plants makes it possible to attribute these formations to the "steppe" ones that require further study and more profound florogenetic analysis.