摘要
甘肃省中部是东亚夏季风活动边缘带,也是我国北方环境敏感带,降水是制约当地农业社会发展的重要因素,因此对该区域过去降水变化开展研究有重要意义。本文在甘肃中部渭源县竺尼山采集油松树轮样本,建立了STD和RES年表。计算表明,RES年表与上年8月到当年7月的年降水总量相关最高(r=0.59),二者存在比较一致的变化趋势,因此竺尼山RES年表可以代表当地过去降水的变化信息,它与同处于东亚季风边缘带的兴隆山和吐鲁沟的树轮年表(也被用来重建了当地的年降水变化)显著相关。三个地点树轮宽度变化一致,树木径向生长均受控于降水。
Background, aim, and scope The central Gansu province is the margin of the East Asian Summer Monsoon （EASM）, and the environmentally sensitive region as well. The EASM related summer precipitation is an important factor for the local economical development. As such, it is very important to recognize the precipitation variations in the past. In this paper, Chinese pine from Gansu province was used to investigate the precipitation variations in the past century and to clutch some clues concerning the strength variations of the EASM in the study area as well. Materials and methods＇ Chinese pine cores were collected on Mr. Zhuni which is located in the central Gansu province. In the laboratory, the standard dendrochronological processes were employed, and the ring-widths of each core were measured with a precision of 0.001 ram. After cross- dating, the COFECHA program was used to control the quality of cross-dating. STD and RES chronologies were developed using ARSTAN program. Pearson correlation analyses were used to identify the relationship between tree-ring chronology and climate factors. The precipitation and temperature from Lintao meteorological station were employed to do ring-width climatic response analysis. By using the KNMI Climate Explorer dataset （http：// www.knmi.nl）, we also explored the spatial representiveness of our precipitation-related chronology within the large-scale of the EASM margin areas. Results The results showed that both RES and STD chronologies were positively correlated with precipitation and negatively with temperature. This was the typical tree-growth- climate response pattern in the arid and semi-arid region. This was a quite similar finding to the previous tree- ring studies on the Chinese Loess Plateau. We found that STD was highly correlated with the temperature and RES with precipitation. The highest correlation was given to RES chronology with the total precipitation from prior August and current July, with r=0.59. That is to say that the RES chronology could represent the annual precipitation variations in the Mr. Zhuni. Meanwhile, no high correlations were found between chronologies （both STD and RES） and local PDS1 dataset. This is because that the study region is located in the margin of the PDSI grid with complicated topography and climate conditions, the 2.5-x2.5- PDSI grid is too big to represent the true conditions of all areas in one grid. We also observed that RES chronology of Mt. Zhuni was significantly correlated with those of Mt. Xinglong and Tulugou which were located in the EASM margin too, with r=0.51 and 0.52 separately. Discussion The study region is located on the western Loess Plateau. The precipitation is mainly concentrated during July to September caused by EASM. Strong EASM leads to more precipitation, and vice versa, in our study, the RES chronology ofMt. Zhuni could be regarded as the precipitation proxy indicating the strength variations of the EASM. We found that 1891 and 2011 were the visible bizarre driest years in the study region during the entire series. The year 1916, 1928, 1940, 1966, 1995, 1997, 2003 and 2000 were also very dry with low precipitation. Except these local exhibitions, there existed high correlations among tree-ring series of Mt. Zhuni, Xinglong and Yulugou, and they all displayed synchronous variation patterns imputing the EASM influences. The drought in 1916, 1923, 1928, 1940, 1966, 1995, 1997, and 2000 were recorded synchronously by three tree-ring series. The droughts occurred during 1928- 1929 was virtually the most severe drought in northern China and many tree-ring series in the northern-central China recorded this drought event. Some studies even showed that strong E1 Nifio was one of the main reasons of drought in northern-central China, such as 1997. From this point of view, tree-ring data is a quite authentic and reasonable proxy to record drought events. The spatial correlation analysis indicated that our RES chronology could represent the precipitation variation over the EASM margin. The tree-ring series of EASM margin could be aspired to use for the EASM variation study in the past. Conclusions RES chronology of Mt. Zhuni could represent local annual precipitation variations. It was similar to other two tree-ring series on the western Loess Plateau, China. The variation pattern is quite synchronous among them, which may be caused by the EASM. Recommendations and perspectives The tree-ring studies in the semi- arid and arid region of China are very important for the understanding of EASM. More studies are needed to give a deep insight to the EASM.
出处
《地球环境学报》
CSCD
2017年第2期119-126,共8页
Journal of Earth Environment
基金
黄土与第四纪地质国家重点实验室开放基金
国家自然科学基金项目(41401060)
中国科学院重点部署项目(KZZD-EW-04-01)
中国科学院青年创新促进会~~
关键词
甘肃竺尼山
油松
树轮宽度
气候响应
Mt. Zhuni, Gansu
Pinus tabulaeformis Carr.
ring width
climatic response
作者简介
通信作者：刘禹，E—mail：liuyu@loess．llqg．ac．cn
