乌兰地区青海云杉和祁连圆柏的树轮宽度:水分记录还是温度记录?
IS THERE A TEMPERATURE OR HYDROCLIMATE SIGNAL IN TREE-RING WIDTH OF QINGHAI SPRUCE AND QILIAN JUNIPER IN THE WULAN REGION,QINGHAI PROVINCE?
王振波 1王淼 1王丰 2秦春 3杨保1
作者信息
- 1. 南京大学地理与海洋科学学院,江苏南京 210023
- 2. 魁北克国立科学研究院水地环境中心,加拿大魁北克,G1K 9A9;GEOTOP地球系统动力学研究中心,加拿大蒙特利尔,H2X 3Y7
- 3. 中国科学院西北生态环境资源研究院,甘肃兰州 730000
- 折叠
摘要
青藏高原东北部是对全球气候变化高度敏感的区域.由于其具有典型干旱、半干旱的气候特征,一般认为该地区树木的径向生长主要受水分条件控制.然而,已有研究发现,在该区域乌兰-都兰及以东地区,影响树木径向生长的气候因子较为复杂,既有水分,也有温度因素.本研究分析了乌兰地区青海云杉和祁连圆柏树轮宽度对气候的响应特征,并与德令哈地区明确指示降水的树轮宽度序列进行比较.结果表明:1)在1956～2010A.D.间,青海云杉树轮宽度记录了当年7月的温度信号,而祁连圆柏树轮宽度与当年7月温度、5～6月降水及5～7月帕默尔干旱指数(PDSI)均显著相关;2)两个树种径向生长对气候的响应在1970～1980 A.D.开始发生了变化:对当年7月温度的响应逐渐增强,而对前一年7月至当年6月降水的响应呈现出先下降再上升的趋势,同时对生长季5～7月PDSI的响应逐渐减弱;3)在1789～2010 A.D.更长的时段内,乌兰地区青海云杉和祁连圆柏与德令哈指示降水变化的树轮序列高度相关.以上结果表明,在器测记录以前的时段,乌兰地区青海云杉和祁连圆柏树轮宽度仍主要反映水分条件(降水和干湿)的变化,而器测记录以来其对当年7月温度的显著响应可能与近几十年来的西北地区暖湿化有关.未来在树木生长-气候响应模式发生转变的地区,需要综合考虑不同时间长度的树轮-气候响应关系来进一步明确树轮序列所包含的气候信息.
Abstract
The northeastern Tibetan Plateau is highly vulnerable to global climate change.Due to the arid and semi-arid conditions,hydroclimate is widely considered to be the factor dominating the radial growth of trees in this region.However,studies have revealed that tree-ring width(TRW)in Wulan and its eastern regions show more complicated climatic responses,to both temperature and hydroclimate variables.In order to investigate the potential of TRW for reconstructing the regional climate,this study analyzed climatic responses of TRW of Qinghai spruce(90 cores)and Qilian juniper(141 cores)in the Wulan region,Qinghai Province.We further compared these chronologies with one composite TRW series developed in the Delingha region which clearly exhibits a robust hydroclimate signal.The results suggest that:(1)Between 1956 and 2010 A.D.,the Qinghai spruce TRW recorded a significant signal of July temperatures of the growing year,while the Qilian juniper TRW responded strongly to July temperatures,precipitations from May to June and Palmer Drought Severity Index(PDSI)from May to July.(2)The climatic responses of TRW of the two species appeared to have been shifted around 1970～1980 A.D.The effect of growing season temperatures on the radial growth of Qinghai spruce and Qilian juniper gradually increased,while the responses to hydroclimate gradually weakened through time,with a U-shaped response to precipitations from previous July to current June for TRW of Qilian juniper.(3)Over a longer period of 1789～2010 A.D.,both species were highly correlated with a hydroclimate-sensitive TRW chronology of Qilian juniper developed from the Delingha region.These findings suggest that the recent warming and humidification may have been a major cause of the increasing temperature control on the radial growth of Qinghai spruce and Qilian juniper in the Wulan region.In contrast to a temperature signal,TRW variations of the two species are more likely dominated by hydroclimatic factors in earlier periods not covered by instrumental records.Future studies are needed to account for growth-climate response at different time spans,especially in regions where this relationship may have been potentially shifted,to better understand the potential of long tree-ring series for climate reconstructions.
关键词
径向生长/青藏高原东北部/气候变化/青海云杉/祁连圆柏Key words
radial growth/northeastern Tibetan Plateau/climate change/Qinghai spruce/Qilian juniper引用本文复制引用
出版年
2024
NETL
NSTL
万方数据