树轮记录的阿尔泰山过去528 a 6—7月平均最低温度变化

June — July mean minimum temperature variations in the Altai Mountains over the past 528 a recorded by tree rings

关键词:  阿尔泰山  新疆落叶松  树轮宽度  气候重建  温度变化

Key words:  Altai Mountains  Larix sibirica  tree-ring width  climate reconstruction  temperature variation

摘要:

全球变暖背景下，探究阿尔泰山气候变化历史及规律，可为当地乃至我国西北地区的经济发展和环境保护等提供可靠、长期的气候背景依据。通过建立阿尔泰山新疆落叶松（Larix sibirica）树轮宽度标准化年表，发现宽度年表与当年6—7月平均最低温度显著相关（r=0.803，n=55，p＜0.01）。基于相关分析结果，利用简单线性回归方程重建阿尔泰山1485—2012年6—7月温度变化序列。结果表明在过去528 a中，该地区存在97个偏暖年、351个正常年和80个偏冷年。研究区共经历了10个暖期和6个冷期，1989—2012年为温度最高的暖期。同时，重建序列记录了我国西北地区数百年前的小冰期事件及近百年来的快速变暖事件，表明研究区气候变化对全球气候变化响应敏感。与大尺度大气环流的相关分析表明，夏季北大西洋涛动（SNAO）通过影响西风强度进而影响阿尔泰山温度变化。

Abstract:

Background, aim, and scope Previous studies on climate change in the Altai Mountains have been constrained by limited tree-ring sampling sites and short-term meteorological records, hindering the development of long-term climate variation series. Against the backdrop of global warming, this study aims to analyze how tree-ring width responds to climatic factors and reconstruct long-term historical climate variations using tree-ring chronologies from six sampling sites in the Altai Mountains. The goal is to explore the alignment and discrepancies between these reconstructions and broader climate patterns, providing a more robust basis for understanding climate change and informing decision-making. Materials and methods Using 120 tree-ring width series from six sampling sites provided by the National Centers for Environmental Information, the regional width chronology was established. Pearson correlation analysis was applied to assess tree radial growth responses to climate factors, and a simple linear regression model was developed to reconstruct selected climate variables. The reliability of the regression equation was tested using a split calibration-verification approach. The reconstruction series was compared with other regional temperature records and subjected to spatial correlation analysis to evaluate its broader representativeness. In addition, the influence of large-scale atmospheric circulation patterns on Altai Mountains temperature variations was examined. Results Correlation analysis revealed a strong positive relationship between tree-ring width and the mean minimum temperature for June—July (r=0.803, n=55, p＜0.01). Based on this, the June—July mean minimum temperature in Altai Mountains from 1485 to 2012 was reconstructed using a simple linear regression equation (T_{min 67}=2.3442W< sub > std +11.9673). The explained variance of the reconstructed equation reached 64.4%, and the high and low temperature years, cold and warm periods of the T_{min 67} are defined. Discussion Larix sibirica, predominantly found at the upper elevational limits of the Altai Mountains, experiences its peak growth period from June to July. Temperatures during this period directly influence cambial activity, growth rate, and duration, thereby affecting tree-ring width. The positive correlation between radial growth and T _{min 67} holds physiological significance. The reconstructed temperature series revealed relatively stable June—July mean minimum temperature variations over the past 528 years, documenting six cold periods and ten warm periods in the region, aligning with most previous temperature reconstructions, including the globally recognized Little Ice Age (LIA) and recent warming trends in northwest China. The reconstructed T_{min 67} series exhibited similar interannual and decadal patterns to temperature records from western Mongolia, the Altai Mountains, and the Northern Hemisphere, indicating that regional climate change is highly sensitive to global climate dynamics. Spatial correlation analysis further demonstrated that the reconstructed T_{min 67} series represents temperature variations across a broader region, including eastern and southern Europe and northeastern Africa. Correlation analysis with large-scale atmospheric circulation revealed that the summer North Atlantic Oscillation phase influences westerly wind intensity, subsequently affecting temperature changes in the Altai Mountains. Conclusions Tree-ring radial growth in the Altai Mountains shows a significant positive correlation with June—July mean minimum temperature. Over the past 528 a, the region experienced ten warm periods and six cold periods, with 1989—2012 marking the warmest period with the highest mean temperature of 15.11 ℃. All the results demonstrated that the temperature change in the Altai Mountains has a good response to global warming. Recommendations and perspectives Based on the tree-ring width chronology, T< sub > min 67 in the Altai Mountains during 1485—2012 was reconstructed, revealing patterns and characteristics of temperature variations over the past 528 years, which provides valuable references for understanding historical temperature changes in Xinjiang and, more broadly, Northwest China.