吉林老白山鱼鳞云杉树轮蓝光强度和轮宽指数与气候响应关系随海拔变化的对比

Comparison of elevational changes in relationships of blue intensity and ring width index in Picea jezoensis with climatic responses in Laobai Mountain of Jilin,China

树轮数据是晚全新世古气候研究中最重要的代用指标。树轮参数各具优缺点,蓝光强度(BI)是一种获取成本低廉的最大晚材密度(MXD)的光学替代参数,其蓝色光反射率或强度最小值(256-BI)与相应的MXD值高度相关,被很多的学者认为是树轮气候学研究中一个具有重要潜能的新兴参数。该研究以吉林老白山3个海拔(900、1200和1500 m)的鱼鳞云杉(Picea jezoensis)为例,分析鱼鳞云杉的BI及轮宽指数(RWI)与气候因子的响应差异,以期为BI参数在树轮气候学的进一步应用提供参考。结果表明:不同海拔鱼鳞云杉BI或RWI对气候的响应趋势基本一致。BI与温度主要呈正相关关系,而RWI与温度主要呈负相关关系,其中BI与当年夏季及生长季最高温度显著正相关,而RWI(低、中海拔)与全年平均气温、当年生长季和全年最低温度显著负相关。BI与当年夏季标准化降水蒸散指数(SPEI)显著负相关,RWI与夏季SPEI负相关关系较弱或为正相关;BI和RWI几乎相反的生长-气候关系可能是早、晚材权衡关系的体现。研究区域鱼鳞云杉的BI参数可能与年轮宽度记录不同的气候信号,在空间尺度上对于当年夏季降水、最高温度以及SPEI的响应好于传统宽度指标。BI与主要气候因子相关关系的时间稳定性好于RWI,因此,BI在树轮气候学的研究中具有一定的应用潜能。

Aims We aim to compare the climatic representativeness of blue intensity(BI)and ring width index(RWI)in Picea jezoensis,and to provide guidance for the further application of BI parameters in dendrochronology.Methods A total of 120 tree-ring cores were extracted from P.jezoensis trees in the Laobai Mountain of Jilin Province.Using the methods of the growth-climate response function analysis and moving correlation analysis,the differences in the responses of BI and RWI to climate change in P.jezoensis along an elevational gradient(namely 900,1200 and 1500 m)were investigated.Important findings The BI(or RWI)in P.jezoensis trees at the three elevations had similar responses to climate.BI was predominantly and positively correlated with temperature,while RWI was predominantly and negatively correlated with temperature.BI was positively correlated with the maximum temperature in summer and growing season.RWI at the low or medium elevations was significantly and negatively correlated with the annual minimum and mean temperatures and the minimum temperature in growing season.BI was negatively correlated with the SPEI in summer,while RWI was weakly or positively correlated with SPEI in summer.This almost inverse growth-climate relationships by BI and RWI may reflect the trade-off between earlywood and latewood.BI and RWI in P.jezoensis in the study area may infer different climate signals.On the spatial scale,the responses of BI to summer precipitation,maximum temperature and SPEI were better than the traditional RWI.The temporal stability of the correlation of BI with main climatic factors was better than that of RWI.Therefore,BI has some potential application in studies of dendroclimatology.