Dendrochronological analysis of the response of forest-forming tree species of the projected Mystygyegan reserve (Vakh river basin) to climate change in the XX-XXI centuries

The purpose of this study is to identify the age-old dendroclimatic dynamics of the state of the forests of the Mestygyegan reserve, as a representative standard of zonal middle-taiga forests of the Vakh river basin under global warming conditions. The main tasks of the work: analysis of tree-ring chronologies of the most important forest growers of this territory (Pinus sibirica, P. sylvestris, Betula pendula), identification of responses of radial growth of trees to average monthly air temperatures and monthly precipitation of the growing season and the previous period (only 18 months), identification of trends and patterns of dendroclimatic responses. They adhered to the methods of wood sampling, cross-dating, standardization of ring width rows (radial gain), and calculation of the function of growth responses adopted in dendroclimatology. For the period 1937-2021, trends were revealed to increase the deficit/excess of heat and precipitation in certain months, in particular with signs of summer drought in recent years. There was a shift in the isolines of the growth responses to an earlier time in spring and later in autumn, showing an elongation of the growing season. There is a shift in the manifestation of dendroclimatic responses from the growth of the current year to the growth of the next year, which may indicate both increased opportunities for the accumulation and redistribution of plastic resources by trees and the influence of pathogens. Grass-roots fires amplify the marked trends. Dendroclimatic response patterns of different tree species have both similarities and differences. The smallest response to climate change in birch, the largest in Siberian pine, which requires the greatest measures to protect and protect cedar trees. In the future of further research - a great detail of the results obtained on the taxational characteristics of the forest and accounting for anthropogenic factors.