The increasing frequency and intensity of extreme climate events have caused serious impacts on the service functions of terrestrial ecosystems and the production and life of human society in recent years. The warm nights (TN90p) variable of the 26 extreme climate indicators was the main factor controlling the tree radial growth of Schrenk spruce (Picea schrenkiana) in the Tianshan Mountains region based on the responses of tree-ring width in the 5 sample sites. Therefore, TN90p in the growth season from May to September (TN90p5–9) during 1735–2016 was reconstructed on the basis of the time stability of the growth–climate relationships. The interpretation rate of variance of the reconstructed equation was 45.4% (R2adj = 44.4%, F = 45.7). The reconstruction showed four relatively high TN90p5–9 historic intervals (1747–1798, 1856–1872, 1906–1951, and 2002–2016) and four low intervals (1735–1747, 1798–1856, 1872–1900, and 1951–2002). The occurrence frequency of extreme high values was higher than that of extreme low values during the reconstruction period of 1735–2016. The extreme values of reconstruction were consistent with historical droughts and large-scale volcanic eruptions, indicating that the reconstruction series had high accuracy. Multi-window spectral periodic analysis and spatial correlation analysis revealed that TN90p5–9 variation in the study area was affected by large-scale sea–air stress factors. In particular, the TN90p5–9 obtained by using R/S analysis (rescaled range analysis) will continue to show an upward trend in the relative period of time in the future. This trend will lead to a further decrease in the radial growth of trees and even trigger forest death events.

中文翻译：

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基于年轮宽度记录的西北天山极端气候历史变异

近年来，极端气候事件的发生频率和强度不断增加，对陆地生态系统的服务功能和人类社会的生产生活造成了严重影响。根据5个样地年轮宽度的响应，26个极端气候指标的暖夜（TN90p）变量是控制天山地区雪莲云杉（Picea schrenkiana）树木径向生长的主要因素。因此，根据生长-气候关系的时间稳定性重建了1735-2016年5-9月生长季TN90p（TN90p5-9）。重构方程的方差解释率为45.4%（R2adj = 44.4%，F = 45.7）。重建显示了四个相对较高的 TN90p5-9 历史区间（1747-1798、1856-1872、1906-1951、和 2002-2016）和四个低区间（1735-1747、1798-1856、1872-1900 和 1951-2002）。1735-2016年重建时期极高值的出现频率高于极低值。重建极值与历史干旱和大规模火山爆发一致，表明重建序列具有较高的准确性。多窗口光谱周期分析和空间相关分析表明，研究区TN90p5-9变异受大尺度海气胁迫因素影响。尤其是使用R/S分析（rescaled range analysis）得到的TN90p5-9在未来的相对时间段内将继续呈现上升趋势。这种趋势将导致树木径向生长的进一步减少，甚至引发森林死亡事件。