On the Relic Phenomena and Influence of Volcanic Rocks on Vegetation of Mountain Steppes in Southern Siberia

Resumo

The influence of volcanic rocks, namely, the Cretacious–Tertiary trachybasalt deposits of the Tamchinsky volcano, on the vegetation of mountain steppes in southern Siberia under the conditions of western Transbaikalia has been established. It is shown that weather-resistant basalts, which are highly various in terms of their geochemical composition, have served as a basis for the formation of unique mountain-steppe communities with the development of peculiar plant life forms. A floristic complex of rosette herbaceous polycarpics combined with sod grasses (Potentilla sericea, Chamaerhodos altaica, Pulsatilla turczaninovii, Silene jenisseensis, Amblynotus rupestris, Festuca lenensis, Aster alpinus, etc.) has been revealed; they form phytocenotically determined synusiae in the studied phytocenoses. It has been established that the Tamchinsky basalt field is a refugium for relics of different times. They include preglacial relics, namely, populations of semishrub wormwoods, Artemisia rutifolia and A. messerschmidtiana. A close affinity between A. gmelinii and A. messerschmidtiana has been proven, taking into account the ecological and morphological and phytochemical data. An increased geochemical background of elements (Ba, Sr, V, Zr, and U) promoted not only the conservation of relic plants but also the morphogenesis of endemic species, peashrub and iris.