Features of spatial structure and cenogenesis relict larch forests of the mountain forest-steppe of Southern Siberia

Abstract

The article provides original information about relict phenomena in the structure of the forest component of the mountain forest-steppe of Southern Siberia (SS). Larch (Siberian larch (Larix sibirica Ledeb.)) shrub-grass forests are characteristic element of vegetation in the forest-steppe of the SS. The oldest are the Pliocene, the most thermophilic analogues of the modern forest-steppe, noted in the foothills of the Western Tannu-Ola ridge (Horlety) is a small leaved larch, dwarf-gmelin wormwood with participation in the community of mountain-Asian elements of ancient Middle-earth. It is important to note that in the species composition of the relict larch forest, the role of characteristic boreal species such as spirea (Spiraea media Schmidt), prickly wild rose (Rosa acicularis Lindl.) is insignificant in comparison with typical elements of semiarid florocenotypes of the Ancient Middle Earth. Among them, participation in the shrub layer of the small-leaved honeysuckle community, an element of the Altai-Dzhungar-Tien Shan relict florocenotype of highland Asian shrubs, is especially significant in phylogenetic terms. In the conditions of Western Transbaikalia, in the spurs of the ridge Malyi Khamar-Daban (Inzagatuy tract) describes the relict larch forest with the participation of characteristic species of the periglacial Pleistocene complex. In the Quaternary period – especially the xerothermic phases of the Holocene, as mountains deglaciate and a relatively warm and temperate climate develops, conditions are created for the formation of a modern mountain forest-steppe in the conditions of the semi-humid climatic regime of the SS. For example, forb-iris-sedge larch, characterized by a rich species composition of herbaceous plants, along with a well-developed undergrowth. This is expressed in the processes of mesoxerophytization of vegetation with the development of floristic complexes of meadow steppes and hemiboreal forests in the structure of phytocoenocomplexes of mountain exposure forest-steppe from Altai to Transbaikalia.

Keywords

• plant species
• phytocoenocomplexes
• hemiboreal forests
• mountain forest steppe
• altai
• transbaikalia