吉尔吉斯斯坦西天山上下林线树轮对气候的响应差异

利用2012年10月采自吉尔吉斯斯坦西天山chon-kyzyl-suu附近的森林上线和下线两个采样点的雪岭云杉树轮样本，建立了上下线树轮宽度年表，结合近百年CRU（0.5?.5）气温和降水资料，分析该地区森林上下线树轮对气候响应的异同。研究表明，森林上下线树轮年表一致性较好，尤其是窄轮出现年份基本相同；对气温响应方面，森林上线树轮年表与春季尤其是4-5月份平均温度显著负相关；而森林下线树轮年表与夏季尤其是6-7月平均气温显著相关。降水方面，树轮年表与上年7月到当年6月降水相关最好，森林下线年表与上年7月到当年6月的降水量相关系数超过0.61；上线也达到了0.49。与中国境内雪岭云杉对气候响应基本相同，位于吉尔吉斯斯坦的西天山北坡树轮宽度同样对降水的响应更为敏感，尤其在森林下线；降水可能是该地区树木生长的主要限制性因子，降水对森林下线树轮径向生长起决定性作用。空间相关分析表明，树轮年表能较好的代表西天山大部分区域上年7月到当年6月的降水量，尤其是西天山北坡吉尔吉斯斯坦境内。

Differences of tree-ring response to climate between upper and lower treeline on West Tianshan, Kyrgyzstan

In this study, we develop two tree-ring width chronologies using the Schrenk spruce tree-ring samples that was collected from the upper and lower treeline of chon-kyzyl-suu in west Tianshan, Kyrgyzstan, and analysis similarities and differences of tree-ring response to climate between upper and lower treeline using temperature and precipitation data from Climatic Research Unit (0.5 ?0.5). Studies result showed that the tree-ring chronologies have a good consistency between upper and lower treeline. Tree-ring width chronologies response to temperature aspects, there is negative correlation and have a good relationship between tree-ring width index which located upper treeline and the temperature in spring (especially in April and May), and there is negative correlation and have a good relationship between tree-ring width index which located lower treeline and the temperature in summer (especially in June and July). The precipitation aspects, the best correlation between tree-ring width chronologies in lower treeline and precipitation from previous July to current June(r=0.61, p<0.000001), and the correlation also reached 0.49 between tree-ring width chronologies in upper treeline and precipitation from previous July to current June. It is same that Schrenk spruce response to climate in Xinjiang, tree-ring width response is more sensitive to precipitation. The precipitation may be a major limiting factor for tree growth in the area, and play a decisive role in lower treeline. The spatial correlation analysis showed that the tree-ring chronologies have a good representative to precipitation from previous July to current June in west Tianshan, especially on the northern slope of Tianshan Mountains in Kyrgyzstan.