祁连山中东部青海云杉径向生长对气候变暖的响应差异

气候变暖对森林生态系统产生了深刻影响，而树木生长对气候变化做出了不同的响应。本研究利用采自祁连山中、东部不同海拔梯度的青海云杉（Picea crassifolia）树轮样本，分别建立了中部和东部6个树轮宽度年表，分析了树木径向生长与各气候要素的关系以及随时间变化的稳定性。结果表明：祁连山中部青海云杉对降水和scPDSI较东部更为敏感。中部树轮宽度年表与当年5—7月的scPDSI极显著正相关（P<0.001），东部树轮宽度年表与前一年9月和当年5月scPDSI显著正相关，表明中部LCH区域青海云杉径向生长主要受当年5—7月土壤水分条件的限制；东部XYH区域则受前一年9月和当年5月的土壤水分的限制。20世纪80年代中东部温度显著升高（P<0.001），中东部树木生长受高温引起的干旱胁迫增强；20世纪90年代以后，由于中部降水增加而东部降水变化不明显，中部树木生长干旱压力得到缓解，东部森林受干旱的限制作用增强。此外，中东部青海云杉与温度、降水和scPDSI的相关关系逐渐趋向一致，未来气候的持续变暖或许将减小中东部树轮-气候关系的差异。

Different responses of radial growth of Picea crassifolia to climate warming in the middle and eastern Qilian Mountains

Global climate warming has profound effects on forest ecosystems. Whether the environmental context affects the response of tree growth to climate change remains unkonwn. In this study， three tree-ring chronologies of Picea crassifolia at different elevation gradients were developed in the middle and eastern Qilian Mountains， respectively. The relationship between radial growth of trees and climatic factors and its stability with time were analyzed. Results showed that the Picea crassifolia in the middle of Qilian Mountains was more sensitive to precipitation and scPDSI than that in the eastern. The tree-ring width chronology was positively correlated with scPDSI from May to July of the current year in the middle of the Qilian Mountains （P<0.001）， and the eastern Qilian Mountains tree-ring width was significantly positively correlated with scPDSI in previous September and current May. It indicated that the tree growth of Picea crassifolia was mainly restricted by the soil moisture conditions from May to July of the current year in the middle of the mountains （LCH）.The eastern regions （XYH） was limited by soil moisture in September of previous year and May of the current year. As the temperature increased significantly since1980s （P<0.001）， the drought stress for tree growth was enhanced in the central and eastern regions， which caused by high temperature. After 1990s， due to the increase of precipitation in the central region and the insignificant change in the eastern region， the drought stress of tree growth in the Middle region was relieved， but it was enhanced in the eastern region. In addition， the correlation between temperature， precipitation and scPDSI of Picea crassifolia is gradually consistent in the middle and eastern Qilian Mountains， and the future climate warming may reduce the difference of tree-ring climate relationship of Picea crassifolia in the middle and eastern Qilian Mountains.