Radial Increment of Dahurian Larch (Lárix dahúrica Turcz.) in the Conditions of the Stanovoy Highlands

The relevance of the work is due to the importance of assessing the sustainability and productivity of forest stands at the upper forest line, taking into account current climate changes. Such assessments allow for a more accurate determination of the resource potential of forest ecosystems, on the one hand, and the carbon sequestration potential for consideration in climate policy, on the other. The aim of this research has been to establish the dynamics of the linear parameters of the annual ring of Dahurian larch in the conditions of the upper forest line of the Udokan Range (the Stanovoy Highlands). To study the parameters of the annual ring (annual ring width in the early and late wood), core samples have been taken from 41 Dahurian larch trees growing in 3 sites in larch sparse forests at altitudes of about 1500 m. An analysis of meteorological characteristics carried out for the period since 1938 till 2021 based on data from the Chara weather station closest to the sampling site has revealed an increase in air temperature in all seasons of the year, the duration of the frost-free period and the number of periods with temperatures above 0, 5, 10 and 15 °C, and the sum of temperatures greater than 5, 8, 10 and 15 °С in the study area. As a result of the work carried out, for the first time for the upper forest line of the Stanovoy Highlands, a generalized Char tree-ring chronology has been constructed based on the parameters of annual rings lasting for 513 years, the statistical indicators of which indicate that the dynamics of increment is characterized by sensitivity to external environmental factors. Dendroclimatic analysis, based on the calculation of the Pearson correlation coefficients between the increment indices of the considered parameters of annual rings and climatic factors for 1938–2019, has revealed that the growth of larch in the territory of the Stanovoy Highlands is mainly limited by the temperature regime of the surface air. The highest correlation coefficient values have been 0.49–0.50 (with the average June air temperature); 0.41–0.49 (with the average temperature for June–July, June–August, and June–September); 0.52–0.53 (with the maximum temperature in June); 0.45–0.52 (with the maximum temperature for June–July, June–August and June–September). Significant (at p < 0.001) correlations have also been found between the sums of air temperatures above 5, 8, 10 and 15 °С and the growth indices, the largest for sums above 15 °С and annual ring parameters (0.43–0.45).