ORDINATION ANALYSIS OF THE STEPPE VEGETATION OF THE BOLSHOY                                  URAN RIVER BASIN (ORENBURG REGION)

Tabul’din Yulay Zakirovich, Teacher, secondary school of Kubanca village (4 Makarenko street, Kubanca village, Perevolotsky district, Orenburg region, Russia); postgraduate student, Orenburg State Pedagogical University (19 Sovetskaya street, Orenburg, Russia), Yulay21@rambler.ru
Yamalov Sergey Maratovich, Leading researcher, Botanical garden- Institute of Ufa Scientific Centre of the Russian Academy of Sciences (building 3, 195 Mendeleeva street, Ufa, Russia), yamalovsm@mail.ru
Petrova Mariya Vladimirovna, Postgraduate student, Botanical gardeninstitute of Ufa Scientific Centre of the Russian Academy of Sciences (building 3, 195 Mendeleeva street, Ufa, Russia), mariya.86.86@yandex.ru

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Background. The article introduces results of a geobotanical research of steppe communities of the Bolshoy Uran river basin in Orenburg region. In spite of a long history of studying vegetation of the Obshchy Syrt, nowadays there are no conrete data from this territory. The aim of the present work is to reveal the diversity of steppe communities of the Bolshoy Uran river basin and to research their ecological and floristic differentiation by the method of ordination analysis.
Materials and methods. The study is based on 79 geobotanical descriptions of steppe communities. To ecologically analyze regularities of grass vegetation dissemination the authors used indirect ordination by the detrended correspondence analysis (DCA-ordination), performed in the CANOCO 4.5 software package.
Results. In the space of two principal ordination axes of geobotanical description the authors formed 5 groups. Group I included communities on stony substrates (sandstone yields, seldom – marl yields). Group II embraced communities of zonal tree-grass arid steppes with prevailing Stipa lessingiana on fairly stony substrates, representing a zonal type of vegetation. Group III united pasture variants of treegrass steppes of the territory under investigation – the so-called Stipa and Artemisia bunches. Rich meadow steppes on mature soils were represented in Group IV. Communities of solonetzic soils, found locally in landscape’s low points, compiled Group V.
Conclusions. As the research result the authors have revealed the diversity of steppe communities of the Bolshoy Uran river basin, represented by stony steppes, species-depauperated arid Stipa lessingiana steppes, pasture derivatives of tree-grass steppes, as well as meadow and solonetzic steppe communities. The study has revealed factors that determine biodiversity of steppe territories under investigation, with most important ones being humidification, richness, stoniness of soil and, to a lesser extent, substrate’s salinity.

steppe vegetation, Orenburg region, ordination analysis.

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