阿尔泰山西伯利亚落叶松径向生长对气候变化的分异响应

在全球气候变暖的背景下, 北半球中高纬度地区出现了树轮径向生长对气候变化的分异响应现象, 但是阿尔泰山优势针叶树种对气候因子响应的稳定性还存在不确定性。该研究选择阿尔泰山中段高海拔西伯利亚落叶松(Larix sibirica)样本建立了树轮宽度年表, 并对年表特征及树木径向生长-气候的动态关系进行了分析。结果表明: 生长季初期和中期的气温是研究区树木生长的主控气候因子; 树木径向生长与当年4月的气温显著负相关, 与当年6-7月的气温显著正相关; 研究区西伯利亚落叶松径向生长与当年4月和6-7月的气温发生了分异现象, 表现为随着气候变化, 树木径向生长对生长季初期由高温引起的干旱的响应敏感性越来越强, 而对生长季中期气温的敏感性表现出先减弱再增强的趋势。阿尔泰山西伯利亚落叶松径向生长对气候变化的响应比较敏感, 适合开展树木生长-气候变化的研究; 检验树木径向生长对气候变化分异响应为该区域基于树木年轮开展历史气候重建和提高未来森林生态系统发展趋势预测的准确性提供了科学依据。

Divergent responses of radial growth of Larix sibirica to climate change in Altay Mountains of Xinjiang,China

AimsThe objective of this study was to determine the temporal stability of relationships between radial growth of Larix sibirica and climatic factors in Altay Mountains.MethodsTree-ring samples were collected at high altitude (2 069 m) in Altay Mountains of Xinjiang, China. Residual chronologies (RES) were established by using the tree-ring width data. Growth-climate relationships were investigated by calculating the Pearson correlation coefficients between tree-ring width chronology and climatic factors. Moreover, the variations in radial growth in response to climatic factors were calculated by a moving correlation function with a 30-year time window using the DendroClim 2002 program. Important findings Temperature in the early and middle growing seasons exerted the greatest control on the radial growth in Larix sibirica of the study region, with a significant negative correlation between the radial growth of trees and the air temperatures in the current April (mean minimum air temperature: r = -0.308, p < 0.05; mean air temperature: r = -0.324, p < 0.05; mean maximum air temperature: r = -0.330, p < 0.05), and a significant positive correlation between the radial growth and temperatures from June to July (mean minimum air temperature: r = 0.499, p < 0.01; mean air temperature: r = 0.456, p < 0.01; mean maximum air temperature: r = 0.431, p < 0.01). The radial growth in Larix sibirica exhibited divergent responses to temperature in April and from June to July. Specifically, with the changes in climate, the radial growth response sensitivity of trees showed a gradually increasing trend to drought caused by high temperature in current April, while the sensitivity to the temperature decreased initially and then increased from the current June to July. Our results show that the radial growth of Larix sibirica in Altay Mountains was sensitive to climatic factors, making it suitable to study the relationships between tree growth and climate change. Under climate change, our findings on divergent response of radial growth in Larix sibirica to climatic factors would provide a scientific basis for accurately reconstructing historical climate and predicting forest ecosystem dynamics based on tree-ring data.