Surface pollen and its relationships with modern vegetation and climate on the Loess Plateau and surrounding deserts in China

Abstract

A dataset consisting of 37 surface pollen samples from forest steppe, steppe, steppe desert and desert in the Loess Plateau and surrounding deserts, China, provides an opportunity to study the relationships between surface pollen assemblages and modern vegetation and climate in this region. The principal components analysis (PCA), correlation analysis and pollen ratios were used to help analyze the pollen data. The modern pollen assemblages are mostly composed of Artemisia, Chenopodiaceae, Poaceae, non-Artemisia Asteraceae, Nitraria and Ephedra. The results suggest that the surface pollen assemblages of different vegetation types faithfully represent the modern vegetation in terms of main composition taxa and dominant types. Correlation analysis between pollen taxa and environment variable shows that mean annual precipitation (MAP) is the major climate variable that controls the modern pollen assemblages. Pollen taxa and environment variable correlation analysis shows that Pinus, Poaceae and Artemisia pollen percentages are positively related with MAP, while some other types, such as Chenopodiaceae, Ephedra and Nitraria pollen percentages are negatively related with MAP. Arboreal/non-arboreal and Artemisia/Chenopodiaceae pollen ratios are positively associated with vegetation types and annual precipitation change, suggesting that they could be applied as useful indicators of moisture variability. Our results have implications for interpreting the fossil pollen data in the study region, particularly on the Loess Plateau, where modern pollen process studies are still sparse.