摘要
本文采用半定量化的植物大化石技术、腐殖化度分析和烧失量方法,重建长白山地哈泥沼泽表层50cm湿度变化过程,探讨控制沼泽表面湿度变化的主导因素,并试图揭示该地过去175年的气候变化,考察植物大化石在大陆性气候下的敏感性。根据^(210)Pb技术和AMS^(14)C定年法确定剖面年代。结果表明,哈泥沼泽表层50cm以泥炭藓泥炭为主,植物大化石除趋势分析揭示植被演替是由水位变化造成的,且3种指标揭示的哈泥沼泽表面湿度变化趋势基本一致,即从0~22cm(约公元1983~2008年)表面湿度明显偏大;22~34cm(约1925~1982年)处于干燥时期;34~50cm(约1834~1924年)沼泽表面湿度较高。通过与最近的靖宇站的气象数据和长春地区的湿润指数对比,发现3种指标重建的表面湿度与降水数据或者湿润指数比较吻合,与温度关系次之,沼泽表面湿度增大发生在夏季降水和年降水均高的年份。由此推测,降水可能是引起沼泽表面湿度变化的主要因素。结论也说明植物大化石和腐殖化度在大陆性气候条件下对沼泽表面湿度变化仍然反应敏感。
Hani mire （42°11′～42°14′N,126°28′～ 126°33′E） is a 16.78km2mesotrophic to oligotrophic peatland and lies in west Changbaishan Mountain,Jilin Province,China.A single monolith （50×10×10cm） at 42°13′31.93″N and 126°31′03.36″E,was dug out from the open area near the wooded zone in Hani mire.We conducted semiquantified analyses on plant macrofossil remains,colorimetric humification and loss on ignition from the top 50cm stratigraphy of Hani mire to investigate wetness dynamics of the mire surface,and to test the sensitivity of plant macrofossils to continental climate change,with chronological support for age-depth modeling by 210Pb assay and AMS 14C dating.In addition,we attempted to discern the dominant control on mire surface wetness.Semiquantitative plant macrofossil analysis mainly followed the quadrat and leaf count protocol developed at the Southampton palaeoecology laboratory.Detrended Correspondence Analysis （DCA） was used to transform the raw floral data into latent indices of mire surface wetness,and the DCA ordination highlights the presence of a clear mire surface wetness gradient along axis 1.The correlation analysis shows there is a positive correlation between DCA axis 1 sores and humification （r=0.359,n =50,p＜0.05）,a positive correlation between DCA axis 1 sores and LOI （r=0.300,n =50,p＜0.05） and a significant positive correlation between humification and LOI （r =0.373,n=50,p＜0.01）.Several wet-shift phases that were identified from three proxies suggest wetter surfaces from 50cm to 34cm （ca.1834～ 1924A.D.）,drier surfaces from 34cm to 22cm （ca.1925～ 1982A.D.） and wetter surfaces occurred from 22cm up to 0cm （ca.1983～2008A.D.）,assuming that the 210pb dating is precise and accurate.The similarities among the three proxies imply a common origin of the variability,and they are interpreted in terms of changing effective precipitation since vertical movement of water in this area is dominant.Precipitation data from Jingyu meteorological station and wetness index for Changchun area suggest surface wetness dynamics inferred from climate proxies coincide well with precipitation data and documentary records.The wet periods were 37.3％,dry periods 20.9％ and normal 41.8％ from 1834A.D.to 1924A.D.There were 12 wet years,11 dry years and 7 normal years in 1925～ 1954A.D.The total annual precipitation was more than multi-year （1955～2008A.D.） mean annual precipitation,and higher precipitation in June,July and August accounted for 57.7％ from 1955A.D.to 2008A.D.Moreover,most wet shifts （1963 ～ 1964,1971 ～ 1975,1993～ 1995,2001,and 2005） from 1955A.D.to 2008A.D.recorded by at least two of three proxies are supported by precipitation data or wetness index.But the data from Jingyu meteorological station show the summer temperature and mean annual temperature at wet shifts from 1955A.D.to 2008A.D.are high and low.So we conclude that mire surface wetness is driven primarily by precipitation,wetter mire surface corresponded to high summer precipitation and high annual precipitation.Plant macrofossil analysis has therefore significant potential to indicate climatic change in continental peatlands,because wet-shift dates recorded from plant macrofossils is consistent with instrumental data and historical literatures.
出处
《第四纪研究》
CAS
CSCD
北大核心
2014年第2期434-442,共9页
Quaternary Sciences
基金
国家自然科学基金项目(批准号:40971036和41001121)
吉林省自然科学基金项目(批准号:20130101081JC)共同资助
