山西五鹿山油松树轮宽度年表的建立及过去百余年5～6月平均气温变化

THE DEVELOPMENT OF A TREE-RING WIDTH CHRONOLOGY AND THE MAY^JUNE MEAN TEMPERATURE VARIABILITY IN WULU MOUNTAIN,SHANXI PROVINCE OF NORTH-CENTRAL CHINA

利用采自山西五鹿山国家自然保护区内的两组油松样本共79根树芯,建立了研究区1893~2008年的树轮宽度年表。统计相关分析表明,油松树轮宽度生长主要受5~6月平均气温(r=-0.55,p<0.001)和同期降水总量(r=0.38,p<0.001)的共同影响,其中5~6月平均气温对树木径向生长的影响更为显著。因此,五鹿山树轮宽度年表可以用来指示5~6月平均气温的变化。在过去105年的有效年表时段(1904~2008年)里,研究区共出现3个高温时段(1924~1932年、1966~1978年和1999~2002年)和2个低温(1937~1951年和1986~1996年)时段,这些高、低温时段可以与周边其他地区树轮重建的气温序列中的高、低温时段相匹配。自1990年以来研究区气温呈逐步上升趋势,但是这一时段的气温仍在历史气温波动范围之内。空间相关分析表明该树轮宽度年表对研究区及周边较大范围的5~6月平均气温都有一定的指示意义。

The Chinese Loess Plateau is located in the North China,one of the most serious regions of soil and water loss in the world, and is also an environmentally sensitive zone. Global warming in the 20th century has deeply influenced the development of the natural ecological systems and the survival environment of human beings, and may threaten the sustainable development of this region. Thus, reconstruction of a long-term background of climate change is imperatively needed. Tree rings is one of the most important high-resolution proxies to investigate the climate history for the last two millennia. Previously,some dendrochronological studies have been carried out in this region. However, the temporal and spatial coverage of tree-ring samples were very limited, more investigations are needed. In the present study, totally 81 tree-ring cores from 45 Chinese pines（Pinus tabulaformis Carr. ）were collected in the early days of July, 2009, from two sites （WLD： 36°31.46＇N, 111°11.46＇E, 1630m; NCS： 36°35. g0＇N, 111°22.06＇E, 1550 - 1600m）in Wulu Mountain, Shanxi Province of North China. The sample sites belong to the temperate continental monsooh climate. The climate is warm and moist with four distinct seasons. The mean annual temperature is 10. 84℃ and the mean annual precipitation is 489.67mm. All tree-ring samples were mounted, air dried, and polished with progressively finer sand paper according to standard dendrochronological methods, and then a ring- width STD chronology spanning 1893 - 2008A. D. was developed using the ARSTAN program based on 79 ring- width series. Correlation analysis revealed a strong negative relationship（r=-0.55 ,p〈0. 001 ）between the tree-ring chronology and monthly mean temperature from May to June（T56） and a less strong positive relationship（r=0. 38, p〈0. 001 ）with the total precipitation from May to June. Subsequently,this ring-width chronology was used to reflect the variation of T56. During the past 105 years （ 1904 - 2008A. D., SSS 〉 0.85 ） tree warm intervals （ 1924 - 1932, 1966- 1978 and 1999 -2002）and two cold periods（ 1937 - 1951 and 1986 - 1996）were identified, and these warm and cold periods matched those warm and cold periods in nearby tree-ring based temperature series pretty well. The increasing tendency of temperature since 1990 in the studied area was obvious, but it still maintained within the scope of temperature variation during the past century. Spatial correlation further confirmed that this tree-ring chronology could not only reflect the May -June mean temperature variation in studied area,but also represent a larger-scale regional temperature variation in North-Central China. Unfortunately, due to the limit of tree age ,we can not detect how did the temperature varied before 1900 ,which present the necessity for developing longer tree-ring chronologies in the future in North-Central China.