Analysis of Tree-Ring Chronologies in Coniferous Forests of Southeastern Kazakhstan

Abstract

The aim of the present research was to study the spatial and temporal patterns in the growth response of spruce to climate change at different altitudes (upper, middle and lower) of mountainous terrain in Southern Kazakhstan. The analysis of the climatic response of the generalized chronologies was carried out by calculating the correlation coefficients (Rs) between the growth indices and monthly precipitations and air temperatures for the period during which the influence of climatic factors on the annual radial increment of wood was possible. This is especially important in cases where there are no assumptions about the possible influence of climatic factors on the growth of woody plants in specific conditions. According to the research, correlation and response analysis shows that the Palmer Drought Severity Index (PDSI) from July 2015 to June 2016 was the main factor limiting the radial growth of Schrenk spruce. The PDSI showed markedly prolonged and rapid hydration from 1980 to 2005 but declined after 2005. There have been three particularly dry years over the past decade (2008, 2014 and 2015). The chronologies have been reconstructed by the PDSI for the last 189 years for the Dzungarian Alatau. A calibration model from 1950 to 2011 explains 42.6% of the actual PDSI variance. The reconstructed PDSI reflects the severe droughts of the 1910s and 1940s that were widespread in the arid zones of Central Asia. The extremely dry years in the 1910s and 1940s are especially noticeable. A ten-year analysis shows that in five periods, i.e., between the years 1830-1840, 1880-1890, 1920-1930, 1950-1960 and 1980-2000, the PDSI increased and decreased in the 1850-1870, 1900-1910, 1940 and 1970 s.