叶尔羌河流域雪岭云杉树轮宽度气候信息的探讨

位于西昆仑山北坡的叶尔羌河是塔里木河的三大源流之一,该流域山区分布的雪岭云杉为过去气候变化研究提供了理想的载体。本文建立了叶尔羌河流域4个雪岭云杉树轮宽度年表和区域合成年表,探讨了树轮年表对叶城气象站气温、降水等气候要素的响应特征。结果表明雪岭云杉树轮年表具有较高平均敏感度、缺轮率和序列间相关系数,年表的质量较高。区域合成年表与叶城站上年6月至当年5月降水量相关系数为0.393,与当年3—9月平均最低气温相关系数为0.624。一阶差相关分析表明,树轮年表与最低气温的高频变化特征并不一致,二者较高的正相关主要是由于温度升高趋势的贡献。树轮年表与乌恰站上年7月至当年4月降水量相关系数为0.535。西昆仑山北坡雪岭云杉树轮年表与周边对水分敏感的树轮气候记录对比表明,其低频变化趋势以及缺年集中出现的年份均具有较好的一致性。由于气候干旱、下垫面条件恶劣,位于叶尔羌河流域的西昆仑山北坡雪岭云杉树木径向生长的限制因子仍然为水分条件,而非气温。

Evaluation on the climatic information of tree-ring width of Picea schrenkiana from Yarkand River Basin

The Yarkand River, which is located at the northern slope of western Kunlun Mountains, is one of the three main sources of Tarim River. The original spruce forest provide ideal material for past climate change in the region. In the paper, the four tree-ring width chronologies and regional composite chronology were developed. The response of tree ring width to climatic factors was analyzed by Pearson correlation method. The results reveal that the mean sensitivity, percentage of missing rings and correlation coefficients among all radii of four spruce tree-ring width chronologies is relatively high, which suggest that they contain abundant climatic information. The correlation coefficients between tree ring width and precipitation from June of previous year to May of the current year and the mean minimum temperature from March to September of Yecheng station is 0.393 and 0.624 respectively. The first order difference correlation analysis indicated that the mean minimum temperature is not consistent with tree-ring width in the high frequency. The positive correlation is mainly contributed by low frequency trend. The correlation coefficient between tree ring width chronology and precipitation from July of previous year to April of current year of Wuqia station is 0.535. The comparison between tree-ring width chronologies of spruce from western Kunlun Mountains and the surrounding tree-ring record that is sensitive to moisture revealed the consistency in high-to-low frequency and extreme drought years. In General, due to the extreme arid climate background and harsh substrate conditions, the limited factors of radial growth of spruce from northern slopes of western Kunlun Mountains is still moisture status.