公元1820年以来甘肃东大山地区树轮宽度对3—9月平均最低温度的响应分析

Growth-climate response analysis between tree-ring width and March-September mean minimum temperature in Dongda Mountain,Gansu,China since 1820 AD

本文以采集于甘肃东大山地区青海云杉树芯样品为研究对象．建立了公元1820年以来该地区标准宽度年表。通过响应函数分析发现，东大山地区树木生长明显受到上年最低温度的影响，树轮宽度较好地反映了东大山地区192年以来3-9月平均最低温度变化特征。东大山地区3-9月平均温度变化表现为两个大的阶段：1820—1950年期间温度变化趋势平稳，略有下降，以冷期为主；1950年以后升温趋势明显，以暖期为主，这一时段气温变化趋势与实际气象观测数据结果一致。功率谱分析显示该序列存在2～4年的准周期变化，与ENSO变化周期有一定的联系。宽度序列与近两百年来的火山喷发事件存在很好的一致性．反映出该地区树木径向生长对火山活动反映敏感．较大的火山喷发与低气温有一定的联系。

This study collected cores of qinghai spruce from Dongda Mountain located in the middle of Hexi Corridor to reconstruct the standard width chronology of this region since 1820 AD. Tree growth in this region is clearly influenced by the minimum temperature of previous year through the response analysis between tree-ring width and March--September mean minimum temperature. And the variation of the tree-ring width is also corresponding to that of March--September mean minimum temperature to some extent. There are two major stages found in the series. From 1820 AD to 1950 AD, the trend of minimum temperature has been stable and been colder phase. On the contrary, it has been rising constantly and been warmer phase with the same variation trend of the meteorological observation since 1950 AD. Power spectral analysis reveals that there are four quasi-periodicities （2 -4 a） within the scope of ENSO cycle. Volcanic eruption events in nearly two hundred years by now could be caught to a large extent by the tree-ring width sequence reflecting the radial growth of trees is sensitive to volcanic activity.