北方草原区主要群落类型表土花粉分析

Study on surface pollen of major steppe communities in northern China

建立花粉与现代植被的关系是利用地层沉积物中的花粉记录恢复古植被、古气候研究的基础工作之一。中国北方草原区39个表土花粉研究表明,蒿属、藜科是草原区花粉组合的主要成分,以禾本科为建群种的草原群落花粉组合以蒿属花粉为主,禾本科花粉多低于10%。禾本科花粉的低代表性可能与其分蘖繁殖、花粉产量低有关。草原区表土花粉浓度与植被盖度相关不明显。典型草原与荒漠草原花粉组合存在着明显的区别,典型草原区藜科花粉百分比一般低于25%,荒漠草原区一般高于25%。DCA分析表明,草原区针叶树、莎草科、石竹科花粉代表较湿润的环境,蒿、藜科、锦鸡儿、柽柳、白刺花粉代表较干燥的环境,阔叶树、禾本科、菊科、毛茛科、蓼科、豆科、唇形科(百里香)、虎榛子+榛、蔷薇科花粉代表的环境介于前两组之间。DCA分析用于草原区花粉组合研究具有较好的环境指示意义。

It is an essential work to survey the relationships between pollen and vegetation for recovering past vegetation and climate from pollen data preserved in sediments. The pollen analysis of 39 sites covering various types of steppe in northern China shows that Artemisia and Chenopodiaceae are the most important pollen types. Artemisia is the dominant taxa of most pollen assemblages, however, the percentages of Gramineae are less than 10% in most steppes. The low Gramineae pollen value may relate with its tillering reproduction. There is no obvious correlation between pollen total concentrations and vegetation covers. The differences between typical steppe and desert steppe are obvious. Chenopodiaceae pollen percentages are usually less than 25% in typical steppes and more than 25% in desert steppes. Detrended Corresponding Analysis (DCA) shows that pollen types of needle trees, Cyperaceae and Caryophyllaceae represent a wetter environmental condition, pollen types of Artemisia, Chenopodiaceae, Caragana, Tamarix and Nitraria represent a drier environmental condition, and pollen types of Gramineae, Compositae, Ranunculaceae, Leguminosae, Labiatae, Ostryopsis+Corylus and Rosaceae represent a transitional environmental condition between the two. DCA is a good method to distinguish different steppe communities in the study of steppe surface pollens.