近400年来塔克拉玛干沙漠南缘红柳沙包孢粉组合与环境变化

POLLEN ASSEMBLAGES OF TAMARIX CONE SEDIMENTARY VEINS AND ENVIRONMENTAL CHANGE IN THE SOUTHERN MARGIN OF TAKLIMAKAN DESERT FOR ABOUT THE LAST 400 YEARS

干旱区发育的红柳沙包沉积纹层不仅是一种计年形式,且蕴含丰富的气候环境信息,是研究荒漠地区近现代高分辨率气候环境变化的有效代用指标。文中依据沉积纹层计年和AMS14 C、137 Cs和210 Pb等测年方法,综合确定了塔克拉玛干沙漠南缘策勒绿洲达玛沟红柳沙包沉积纹层的年代序列,并通过孢粉组合特征分析,利用WAPLS方法重建了近400年来的古植被和古气候。研究表明,1590—1813年,孢粉以草本和灌木类型占据优势,形成以蒿属、藜科、禾本科和柽柳属为主的荒漠灌丛植被类型,气候以暖干为主;1814—1930年,孢粉以灌木类型占据绝对优势,以柽柳为主,后期草本花粉增加明显,为从荒漠灌丛到荒漠草原的过渡期,气候波动较大;1931—2010年,孢粉仍以灌木和草本类型为主,形成以柽柳属、禾本科和蒿属为主的荒漠草原,平均气温小幅度下降,降水明显增多,气候总体表现为冷湿,该阶段大量出现以大禾本为主的农作物孢粉,表明这一时期人类活动对气候环境影响逐渐增大。

The Tamarix cone sedimentary vein in arid area is not only a means of counting years, but also contains climate and environment information. Therefore it can be used as an effective method for the research of modern high resolution climate change in arid areas. Based on sedimentary vein counting and the dating methods such as AMS ^14C, ^137Cs and ^210Pb, this article has established the time series of Tamarix cone sedimentary veins in the Damagou, Cele Oasis, Southern margin of the Taklimakan desert, and by means of sporopollen assemblage analysis and WAPLS, reconstructed the paleovegetation and paleoclimate for the last nearly 400 years. The research results show that： from 1590 to 1813, the pollen type is dominated by herbs and shrubs, formed the desert-shrub vegetation mainly consisting of Artemisia,Chenopodiaceae, Gramineae climate at that time is warm and Tamarix, the and dry; from 1814 to1930, the shrubs pollen occupies the absolute advantage, mainly containing Tamarix, in the later stage the herbs pollen has increased significantly, is a transition period from the desertshrub to desert-grassland, the weather has experienced a transition changing from the warmdry to the cold-wet; from 1931 to 2010, the pollen and spore types are still dominated by herbs and shrubs, forming the desert-grassland vegetation mainly containing the Gramineae, Tarnarix and Arternisia, the average temperature has dropped slightly, whereas the precipitation has increased obviously. On the whole, in the stage it is a relatively cold-wet stage. In this period the cereals pollens mainly containing the crops have increased obviously indicates that the influence of human activities on the climate and environment has increased gradually.