Modern changes of the high-mountain landscapes and glaciation in Southern Siberia (Russia) by the example of the Eastern Sayan mountains

The period of observations of glaciation of the Munku-Sardyk mountain massif in Siberia is one of the longest, i.e. 155 years. However, the data obtained are scattered and not systematic. The paper presents an integrated analysis of the materials collected since the first description by the explorer of Siberian mountains G.I. Radde Istoriy (1896) and extended by Peretolchin (1908) and Komarov (1953), as well as by glaciologists Maksimov (1965), Arefiev and Mukhametov (1996). The authors considered the current state of the glaciers and interaction of natural geosystems of the massif taking into account the nival-glacial processes. Since the beginning of the current millennium, regular observations have been conducted on the Munku-Sardyk massif by the V.B. Sochava Institute of Geography SB RAS, Limnological Institute SB RAS, and East-Siberian State Academy of Education. The studies revealed the leading landscape-forming factors and examined the landscape structure of the surroundings of the contemporary nival-glacial geosystems with due regard for the manifestations of altitudinal zonation. A medium-scale landscape-typological mapping was carried out. Presented are the quantitative parameters of the dynamics of the nival-glacial geosystems obtained on the basis of modern remote sensing instruments, GPS measurements and surface laser scanning using GIS analysis. The stump and stem of larch detected in the valley of the Bugovek River 300 m above the contemporary upper forest limit and 1330 m up the valley show that most likely there was no glaciation during the Atlantic period (7000–7300 years ago). The modern glacier complex has formed only during the last 4000–5000 years. The trend of shrinkage of glaciers since the end of the Little Ice Age can be traced, especially in recent years. The length and area of the open part of the glaciers have decreased by half (from 0.68 to 0.34 km²). The presence of small forms of glaciation on the southernmost limit of the Siberian glaciation 1500 m below the theoretical (climate) boundary suggests that this area can be considered a unique key site to identify trends in development of the mountain and nival-glacial geosystems, and provides an opportunity to built reconstructive and predictive models of development of mountain landscapes under the conditions of ever-increasing anthropogenic influence.