利用生态学和树轮年代学手段试析柴达木盆地东缘山地森林年龄结构与气候变化的关系  

REGIONAL PATTERNS OF TREE AGE STRUCTURE IN NORTHEASTERN QAIDAM BASIN： CLIMATIC INFLUENCES： A CASE STUDY BY USING METHODS OF ECOLOGY AND DENDROCHRONOLOGY

作　　者：田华[1] 邵雪梅[1,2] 尹志勇[1,3] 张慧[1,4] 汪洋[1,4] 陈锋[1,4] 

机构地区：[1]中国科学院地理科学与资源研究所、中国科学院陆地表层格局与模拟重点实验室,北京100101 [2]中国科学院青藏高原地球科学卓越创新中心,北京100101 [3]DepartmentofMarineScienceandEnvironmentalStudies,UniversityofSanDiego,CAU.S.A92110 [4]中国科学院大学,北京100049

出　　处：《第四纪研究》2015年第5期1209-1217,共9页Quaternary Sciences

基　　金：中国科学院战略性先导科技专项项目（批准号：XDA05080201）和国家自然科学基金项目（批准号：41071061）共同资助

摘　　要：选取柴达木盆地东缘山地尔日格为研究剖面,对坡面上的祁连圆柏（Sabina przewalskii Kom.）沿不同海拔高度进行采样.在利用交叉定年手段对所有样芯定年之后,确定了样芯的起始年和结束年（死亡年龄）,然后利用树髓心年龄估算法和研究区域胸高年龄经验值最终确定了树木活体植株开始生长的年龄（长树年龄）.根据研究坡面上树木长树或死树年份随海拔和时间变化的变化规律,探讨了它们与气候变化之间的可能关系,从而用来作为树轮宽度重建的佐证手段之一.结果表明：在森林上部和中部,随海拔的升高,树木的年龄呈递减趋势;在森林下部,随海拔的降低,树木年龄趋于年轻化;整个坡面长树峰值出现在公元1200年左右,长树主要集中在森林中部的3900～4110m之间;树木死亡的峰值出现在公元1600年之后的50年间,死树主要集中在森中上部的4100～4210m之间.同时,还发现在坡面树木死亡较集中的时期,森林树木更新数目较低,尤其是在森林上部;而通过对不同海拔高度上最老树的生长年龄分析,发现在坡面长树比较集中的时期,森林下部有往更低海拔处长树的趋势.将研究坡面长树和死树随时间变化的分布情况与研究区附近利用树轮宽度重建的乌兰过去1000年上年9月到当年4月平均温度和德令哈过去1000年上年7月至当年6月降水量进行对比,发现在40年尺度上,高温对应着树木高生长数目,低温并且降水量由多变寡则对应着树木低生长数目和高死亡数.表明：温度的升高有利于研究坡面祁连圆柏更新的发生,森林密度增大,森林中部幼树更新存活数量最多,森林下部有往更低海拔处长树的趋势,森林上限随海拔的升高密度降低、树木趋于年轻化;反之,气候干冷,树木更新条件变差,受影响的区域主要集中在森林中部-森林林线中上部范围内,死树相对比较集中.In this study, a sufficient number samples of Qilian Juniper （Sabina przewalskii Kom.） were collected using quadrats for analyzing the response of the forest age structure to climatic change. The sampling site is along a steep slope of Errige, Ela Mountain, which is a mountain range of Kunlun-Buerhanda Mountains located at the eastern margin of the Qaidam Basin. Tree cores were dated following standard dendrochronological method. For those samples that failed to intercept the pith, the method of initial radial growth was employed to estimate the number of missing rings. Then a mean age to coring height was added to obtain the final tree age. The distribution pattern of the tree ages along the forest slope suggests ： （ 1 ） An abundance of trees were established around 1200A.D. This is a very prominent feature which is especially obvious in the central section with elevation from 3900m to 4110m; （2） A lack of tree establishments from 1601A.D. to 1650A.D. with a peak in tree death in the upper section from 4100m to 4210m. The oldest stands at different elevations show that trees might regenerate at lower elevations at the same time when most individuals established. The effects of climate variations on tree age structure were analyzed for the past 1000 years with tree-ring records-derived climatic time series, including the Wulan mean temperature from prior September to current April （T94） and the Delingha total precipitation from prior July to current June （P76）. The strongest association between tree regeneration and temperature variation is on 40-year scales with pearson correlation coefficient r = 0. 464 （p = 0. 030）. During the period of 1120A.D. to 1560A.D., T94 is usually above the average temperature of the past （ -7.34℃ ） , and warm conditions are believed to result in enhanced establishment and survival. When temperature fell below the average, especially in the next 50 years after 1560A.D., less regenerated stands as well as a higher mortality can be observed. The influence

关 键 词：树龄估算 树木更新 树木死亡 气候变化 

分 类 号：P467[天文地球—大气科学及气象学] Q948[生物学—植物学]