去趋势方法对建立不同海拔鱼鳞云杉-气候关系的影响

Effect of detrending methods on the relationship establishment between chronologies of Picea jezoenssis var. komarovii and climate factors along altitudinal gradient

为探讨不同去趋势方法对建立不同海拔梯度鱼鳞云杉年表与气候因子关系的影响,完善鱼鳞云杉气候响应机制研究,以长白山北坡不同海拔鱼鳞云杉(Picea jezoenssis var.komarovii)为研究对象,采用保守曲线(NEP or LINE)、样条函数(CSS,35年步长)和区域曲线(RCS)3种去趋势方法建立树轮宽度年表.结果表明:(1)3种去趋势得到的年表对气候因子的响应特征具有一定的相似性,长白山北坡不同海拔鱼鳞云杉均与当年5月气温显著正相关(P<0.05).(2)去趋势方法对鱼鳞云杉生长-气候关系的影响在不同海拔梯度上有所差别.去趋势方法对低海拔鱼鳞云杉样本年表信号影响最明显,对中高海拔鱼鳞云杉样本年表信号无明显影响.利用区域曲线法得到的年表对降水更为敏感,利用保守曲线法和样条函数法得到的年表则对温度更敏感.(3)中海拔(AZYL处)鱼鳞云杉年表在多项指标上明显优于其他两个海拔梯度,且表现出与当年生长季初期温度显著正相关(P<0.05),与上年生长季温度、当年春季和生长季降水显著负相关(P<0.05).低海拔主要受到生长季温度的影响,而高海拔鱼鳞云杉主要受到上年生长季降水的作用,且与当年8月降水显著负相关(P<0.05).综上,去趋势方法对建立年表-气候关系的影响与年表自身气候敏感性有关,长白山不同海拔鱼鳞云杉去趋势方法研究中,区域曲线去趋势法总体上要优于保守曲线法和样条函数法,使用区域曲线去趋势方法有利于在年表中保留较多与降水相关的气候信号.

The effect of detrending methods on the relationship between the chronologies and climate factors along altitudinal gradient was discussed in this paper. The tree-ring width data of Pieeajezoenssis var. komarovii on the north slope of the Changbai Mountain were selected. The chronologies were developed by three different detrending methods： negative exponential function or linear regression curve （NEP or LINE）, cubic smoothing splines （CSS, 35 years） and regional curve spline （RCS）. The results showed： （1） The chronologies developed by three different detrending methods were similar in inerannual variation and response to climate. The growths were positively and significantly related to monthly mean temperature in May at all sites （P 〈 0.05）. （2） The impacts of detrending method on growth-climate relationship changed along altitudinal gradient. The detrending method strongly influenced the signals of chronology at low altitude, but did not have much effect on trees at middle altitude. The chronologies developed by RCS were sensitive to precipitation. The chronologies developed by NEG or LINE and CSS were sensitive to the temperature. （3） The trees at middle altitude were specifically related with climate. Therefore, the detrending method should be considered in analysis of relationship between tile chronology and climate factors along the altitudinal gradient.