Based on the original and published data, 26 С₄-plant species and subspecies from 18 genera and 7 families have registered in the flora of Buryatia. 2 and 5 families belong to monocots and dicots respectively. The number of С₄-plant species is estimated as low, and the reason for this fact is the distinctively boreal pattern of the regional flora in general. The most of С₄-plant species belong to Poaceae and Chenopodiaceae, while other families are represented by 1–3 species. No genera comprising many С₄-plant species have been recorded, only Amaranthus and Bassia are represented by the 3 species each, while other genera contain 1–2 species. In the life form spectrum supremacy of annuals should be highlighted, in contrast to the total flora of Buryatia where the proportion annuals/perennials is almost opposite. Although perennials are in a little number (4), 2 of them are well manifested in the regional steppe vegetation when assessed through a combination of frequency and abundance in plant communities. Meanwhile, the common share of the С₄-plants fraction in the steppe vegetation throughout the whole Transbaikalia is not significant. In connection with annuals supremacy, the predominance of ruderals in the spectrum of life strategies occurs. Importantly, human impact sufficiently contributes to the predominance of ruderals but not stress-tolerants. The habitat-mediated differentiation of the С₄-plants fraction shows the superiority of xerophytic groups, which is connected with the ability of С₄-plants to high photosynthesis rates under high temperature and insolation due to the CO₂ fixation even in the moisture-deficit condition. The portion of hygrophytic plants is rather small (4 species), however very specific being represented by species from genera widely distributed in tropics and subtropics. The one species, namely Pycreus nilagiricus, is a very rare species grows in wet littoral habitats around the hot geothermal spring in Northern Baikal Region. Presumably, it is a relic of pre-Pleistocene, and listed in the regional Red Data Book [2013]. In the chorological spectrum species of the wide distribution areas, like Eurasian, Holarctic, and Cosmopolitan, prevail (17 species). Most of them are ruderals. Asian species are less numerous (8 species) and represented by steppe plants of various life strategies. Comparing to any local flora of the region, a relatively large percentage of Central-Asian and East-Asian plants have revealed in the fraction. In general, all spectra of the fraction of С₄-plants reflect its strong specificity comparing to the regional flora of Buryatia.

Anenkhonov Oleg Arnoldovich, Doctor of Sciences (Biology), Principal Research Scientist, Head of Laboratory, Institute of General and Experimental Biology SB RAS, 6, Sakhyanova st., Ulan-Ude, 670047, Russian Federation, e-mail: anen@yandex.ru 

Ivanova Larisa Anatol’evna, Candidate of Sciences (Biology), Head of Laboratory, Institute Botanic Garden UB RAS, 202a, 8 March str., Ekaterinburg, 620144, Russian Federation; Senior Research Scientist, Tyumen State University, 6, Volodarsky st., Tyumen, 625003, Russian Federation, e-mail: Larissa.Ivanova@botgard.uran.ru 

Ivanov Leonid Anatol’evich, Candidate of Sciences (Biology), Senior Research Scientist, Institute Botanic Garden UB RAS, 202a, 8 March st., Ekaterinburg, 620144, Russian Federation; Senior Research Scientist, Tyumen State University, 6, Volodarsky st., Tyumen, 625003, Russian Federation, e-mail: leonid.ivanov@botgard.uran.ru 

Ronzhina Dina Aleksandrovna, Candidate of Sciences (Biology), Senior Research Scientist, Institute Botanic Garden UB RAS, 202a, 8 March st., Ekaterinburg, 620144, Russian Federation; Senior Research Scientist, Tyumen State University, 6, Volodarsky st., Tyumen, 625003, Russian Federation, e-mail: Dina.ronzhina@botgard.uran.ru 

Liu Hongyan, Philosophy Doctor, Professor, College of Urban and Environmental Sciences, Peking University, Shaw Bld. 2, 5 Yiheyuan Rd., Haidian Dstr., Beijing, 100871, China, e-mail: lhy@urban.pku.edu.cn

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С₄-plants, flora analysis, С₄-plants ecology, С₄-plants geography, annuals and biennials, ruderal plants, Baikal region

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