Study on surface pollen of major steppe communities in northern China
北方草原区主要群落类型表土花粉分析

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.