【摘要】 河北省木兰围场国家级自然保护区是我国京津冀地区重要的生态屏障。为了解该地区的历史气候变化过程,助力生态保护和治理,根据树轮气候学方法,研究采用围场地区油松和鱼鳞云杉的树轮资料,分别建立2种树木的标准化年表、差值年表和自相关年表,分析各年表与气候因子及生态气候指标的相关性,并重建历史气候序列。结果表明:研究区内树木的径向生长主要受夏季气温和年降水量的影响,各年表均与湿润指数及干燥指数显著相关(P<0.01)。利用油松标准化年表重建的木兰围场5—6月均温、5月气温及干燥指数序列,其方差解释量分别达到48.1%、39.9%和33.8%。重建结果与相邻地区的树轮研究一致并与20世纪重大旱灾记录对应,证明重建可靠并说明区域气候变化有一致性。对重建序列进行的滑动平均和功率谱分析表明,1909—2008年间,围场地区大致经历了4个高温干旱期和3个低温湿润期,并存在准21年的显著周期。更多还原

【Abstract】 The Mulan Weichang National Nature Reserve,located in northern Hebei province,adjacent to southeastern Inner Mongolia,is an important ecological barrier and nature reservoir for Beijing-TianjinHebei region. Cognizing the historical climate change of this area will benefit the ecological protection and management of North China Plain. As an essential research technique for the climate variability and predictability( CLIVARl), dendroclimatology tackles problems of present and past climate with information of dated tree-rings. According to the theories of dendroclimatology,we developed two-group standard chronologies( STD),residual chronologies( RES) and autoregressive chronologies( ARS)based on tree-ring widths of Chinese pine( Pinus tabuliformis) and Yeddo spruce( Picea jezoenssis var.komarovii) from two sampling points in the nature reserve and all the chronologies were significantly correlated with each other. The correlation analyses between chronologies and climate factors showed that the radial growth of both arbor species was closely related to summer temperature and annual precipitation. Among all the calculations, STD of Chinese pine( STDpine) and May-June mean temperature had the maximum correlation coefficient( r =- 0. 654,P < 0. 01). Additionally,we investigated the relationship between chronologies with ecoclimatic indices. The analysis suggested that tree-ring growth was highly influenced by humidity index and aridity index. Using regression analysis,the mean temperature of May to June,the temperature of May and annual aridity index from 1909 to 2008 were reconstructed on the basis of STDpine. After calibration,the explained variances of the three reconstructions value were 48. 1 %,39. 9 % and 33. 8 % respectively. The trend of change of each estimated series was consistent with the observed data. In addition,the estimated and observed aridity indexes were both better correlated with temperature than precipitation,indicating that the contribution of temperature to the aridity of the study area was larger than precipitation. During the entire reconstructed series,the most distinctively warm period occurred between the 1910 s and 1930 s. Soon afterwards,the temperature had a rapid fall and reached the lowest point in 1935. After that,it gradually increased and lasted for the next five years,then began to decrease again. Although there was a slight rise from 1957 to 1968,the series showed a moderate descending tendency for the next 40 years. The temperature has increased rapidly since the middle 1990 s,showing a warming period.There were four xerothermic periods and three clammy periods in the past one hundred years. The intervals above average of each reconstructed series comprised 1909 —1929,1939 —1948,1980 —1989 and 1997 —2008,while the below ones were consisted of 1930 —1938,1949 —1979 and 1973 —1979. A significant cycle of quasi 21-year was also detected in the series. Moreover,spatial correlation analyses revealed that the reconstructions were regionally representative. The estimated May-June mean temperature and May temperature can be well comparable with previous research of surrounding areas,as well as the historical drought events.更多还原