云南小中甸地区丽江云杉径向生长对气候变化的响应

Responses of Picea likiangensis radial growth to climate change in the Small Zhongdian area of Yunnan Province,Southwest China

丽江云杉原始林是云南省香格里拉县小中甸地区的主要森林类型.本文采用树轮年代学的方法分析了丽江云杉年轮宽度对气候变化的响应;选取相对保守的结果负指数曲线或线性回归拟合生长趋势建立年表,进行了不同时间尺度的气候因素与差值年表(RES)序列的相关及响应函数分析,并利用特征年分析了产生宽窄年轮的原因.结果表明:研究区丽江云杉的径向生长与温度升高在1990—2008年存在一定的"分离现象";上一生长季的水热状况是限制丽江云杉当年生长的主要气候因子,特别是上年7月的气温对当年径向生长具有负反馈作用,而上年7月的充足降水则促进当年的径向生长;上年生长季温度与降水变化的相反趋势是导致宽窄年轮形成的主要原因;丽江云杉的生长对帕尔默干旱指数(PDSI)的变化不敏感.

Picea likiangensis（Franch.） Pritz.primary forest is one of the dominant forest types in the Small Zhongdian area in Shangri-La County of Yunnan Province.In this paper,the responses of P.likiangensis tree-ring width to climate change were analyzed by dendrochronological methods,and the dendrochronology was built by using relatively conservative detrending negative exponential curves or linear regression.Correlation analysis and response function analysis were applied to explore the relationships between the residual chronology series（RES） and climatic factors at different time scales,and pointer year analysis was used to explain the reasons of producing narrow and wide rings.In the study area,the radial growth of P.likiangensis and the increasing air temperature from 1990 to 2008 had definite ＇abruption＇.The temperature and precipitation in previous year growth season were the main factors limiting the present year radial growth,and especially,the temperature in previous July played a negative feedback role in the radial growth,while the sufficient precipitation in previous July promoted the radial growth.The differences in the temperature variation and precipitation variation in previous year were the main reasons for the formation of narrow and wide rings.P.likiangensis radial growth was not sensitive to the variation of PDSI.