Climate-growth relationships of Schrenk spruce and precipitation variability at the high-mountain areas of the northern Tien Shan

This article presents a new tree-ring chronology of Schrenk spruce (Picea schrenkiana Fisch. et Mey.) developed based on the samples collected at the upper tree limit of the northern Tien Shan (southeastern part of Kazakhstan). The correlation analysis with daily climate data revealed that precipitation in the period from the previous July 8th to November 5th is the main limiting factor of tree-growth r = 0.648 (p<0.05). The obtained chronology was used to reconstruct precipitation in the period from 1829 to 2016. The reconstruction explains 41% of the variance in instrumental precipitation records during the calibration period 1948-1987. The reconstruction revealed six extreme years (± 2σ). Extreme drought years were detected in 1846, 1886, and 1912, and extreme wet years were detected in 1879, 1917, and 1920. Both the occurrence of extreme years and variation of increase/decrease of the amount of precipitation changed significantly during the last 70 years. The amount of precipitation increased in the periods 1829-1843, 1856-1869, 1880-1905, 1920-1935, 1946-1955 and 1978-1993 and decreased in 1843-1856, 1869-1880, 1905-1920, 1935-1946, 1955-1978 and 1993-2016. The Morlet wavelet analysis revealed ~2-4, ~5-7, and ~10-16 year cycles, indicating a possibility to connect the precipitation variability in the study area with the oscillations of certain atmospheric circulation indices. The study provides new information for understanding high-mountain environmental changes in the northern Tien Shan.