Centuries-old climatic trends of transformation of the Siberian stone pine forests in different forest vegetation zones of the Western Sayan Mountains

The article highlights the results of a paleobotanical study of peat deposits in different forest zones and types of habitats in the Western Sayan, where the Siberian stone pine Pinus sibirica Du Tour is currently the dominant species. Based on paleocarpological and radiocarbon analyzes, changes in vegetation, climate and landscapes from 8000 years ago to the present have been reconstructed. The material for the study was the macroremains of fossil plants. Changes in the species composition of macroremains of dominant plant species in each section made it possible to combine them into macrocomplexes, each of which characterizes a certain time and landscape-climatic regime. Carpograms were constructed for four sections, with a detailed characteristic of fossil macrocomplexes by species composition. When analyzing the morphological and anatomical physiognomy of each fossil object according to the degree of preservation, they were differentiated into two groups of plants - the local reflecting peculiarities of the habitat (facies) and the adjacent one characteristic of a larger territorial complex (paleolandscape). Their combination gives an idea of the change in the landscape situation in centuries of climate change. In each group, the edificator and dominants of past phytocenoses, fixed by macrocomplexes of fossils, were determined using the method of ecological-cenotic analysis. The dynamics of the composition and phytocenotic structure of plant communities, replacing each other in a thousand-year history, has been established. A quantitative assessment of the climatic situation is given, which determines their change in different climatic epochs. The repeated displacement of the upper forest boundary was established with conjugate changes in heat and atmospheric moisture, which manifested themselves simultaneously in the study areas. On the example of the Siberian stone pine formation, represented in different forest areas by three different climatic facies of the formation, it is shown that in each of them, with the trends of climate change common for the mountains (warming or cooling, as well as changes in atmospheric moisture), centuries-old changes of communities had their own specific features