Radial Growth and Response Mechanism of Larix Sibirica in the Eastern Altay Mountains Under the Background of Climate Change

Abstract

Against the background of climate warming and humidification in Xinjiang, China, the so-called ‘divergence problem’ reduces the stability of tree rings in response to climate, and affects the reliability of reconstructed models based on tree rings and the accuracy of historical climate series. Investigation of the divergence problem is crucial to improve our understanding of the response patterns of trees to climate warming, and provide a scientific basis for accurate climate reconstruction and simulation of forest dynamics. Based on tree-ring width data for Siberian larch (Larix sibirica Ledeb.) growing at low elevations in the eastern Altay Mountains, in this study we analyzed the response relationship between radial growth of trees and climatic factors in the context of abrupt climate change in this region. We calculated the proportional contribution of five climatic factors to the radial growth of trees, and discussed the response mechanism of radial growth of L. sibirica in combination with large-scale atmospheric circulation. The results indicated that the radial growth of L. sibirica was mainly affected by water stress. Before climate change (1961–1990), the radial growth of L. sibirica was mainly limited by the mean temperature in the previous June. After abrupt climate change (1991–2020), radial growth was significantly positively correlated with winter soil moisture, indicating that high temperatures in the following spring limit the radial growth of trees in the early stages of the growing season. The contribution analysis results revealed that, before 1990, the proportional contribution of temperature to radial growth of trees exceeded 60%. Since 1990, the proportional contribution of water (precipitation and volumetric soil water) to radial growth of L. sibirica increased. This might reflect the combined effects of local climatic conditions and large-scale atmospheric circulation.

Keywords: Altay Mountains, Larix sibirica, tree-ring, Response analysis, Atmospheric circulation