利用采自新疆东部的雪岭云杉和胡杨树轮样芯研制出区域树轮宽度年表。相关分析发现雪岭云杉区域树轮宽度年表与上年8月至当年7月标准化蒸发指数（SPEI）变化有较好相关性，相关系数为0.67（P<0.01，n=54），同时胡杨区域树轮宽度年表也表现出较强的干湿变化信号（r=0.48，P<0.01，n=54）。利用线性回归模型重建了新疆东部1725—2013年上年8月至当年7月SPEI变化，方差解释量为45.3%。利用雪岭云杉区域树轮宽度年表能够较好地重建新疆东部自1725年以来的上年8月至当年7月的SPEI变化，方差解释量达45.3%。重建结果揭示新疆东部1725—1728年，1737—1758年，1765—1804年，1829—1834年，1845—1852年，1888—1904年，1915—1923年，1932—1961年，1969—1973年，1986—2001年偏湿；1729—1736年，1759—1764年，1805—1828年，1835—1844年，1853—1887年，1905—1914年，1924—1931年，1962—1968年，1974—1985年，2002—2013年偏干。胡杨区域树轮宽度年表与雪岭云杉区域树轮宽度年表所指示的干湿变化在年代际上存在一致性，但是胡杨对干湿变化响应往往滞后于雪岭云杉。新疆东部干湿变化与天山中西部干湿变化在年际变化上存在很强一致性，但在年代际变化上存在显著差异，并与甘肃河西走廊干湿变化存在紧密联系。%The regional tree-ring width chronologies of Populus euphratica and Picea schrenkiana were developed for eastern Xinjiang, northwestern China. The climate response analysis shows the regional tree-ring width chronology of Picea schrenkiana had a good correlation (r=0.67)with August-July standardized precipitation-evapotranspiration index (SPEI). Based on the regional tree-ring chronology of Picea schrenkiana, we developed a August-July SPEI reconstruction of eastern Xinjiang for the period AD 1725-2013. The SPEI/tree-growth model accounts for 45.3% of the observed SPEI variance during the period 1960-2013. The SPEI reconstruction reveals valuable information about dry periods and severe drought events over the past 289 years: periods of relatively damp years are identified for AD 1725-1728, 1737-1758, 1765-1804, 1829-1834, 1845-1852, 1888-1904, 1915-1923, 1932-1961, 1969-1973 and 1986-2001. Dry periods with below-average SPEI occurred in AD 1729-1736, 1759-1764, 1805-1828, 1835-1844, 1853-1887, 1905-1914, 1924-1931, 1962-1968, 1974-1985 and 2002-2013. Spatial field correlations of our SPEI reconstruction and tree-ring width chronology of Populus euphratica with the gridded SPEI data reveal that they both have strong regional drought signals. The drought reconstructions of Xinjiang show the strong common signals, and there are also some regional differences in different parts of Xinjiang. The central-west Tianshan Mountains appear damp trend during the recent years, while the eastern Xinjiang appeared a dry trend, and strongly associated with the drought series from the monsoonal areas of China. Thus, the eastern Xinjiang is likely to be an important geographical boundary in the arid and semiarid regions of the mid-latitude Asia. The regional tree-ring width chronologies of Populus euphratica and Picea schrenkiana show that similar trends of drought changes. However, the response of Populus to dry and damp change tend lagged behind the changes of Schrenk spruce.
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