Pollen-vegetation-climate relationships in some desert and desert-steppe communities in northern China

In this paper, we consider the relationship between pollen assemblages, vegetation and climate in some desert and desert-steppe areas in northern China using both surface soil samples and pollen trap samples. Discriminant analysis shows that samples originating from different climatic or geographical regions can be separated reliably on the basis of pollen assemblage regardless of sample type. DCCA analysis indicates that surface soil pollen assemblages show significant correlations with climate parameters. DCCA Axis 1 is negatively correlated with the mean temperature in the warmest month (MTwa; r = -0.58), whilst axis 2 is positively correlated with mean annual precipitation (P-ann; r = -0.73). Artemisia-to-Chenopodiaceae ratios are generally lower in desert areas than in desert-steppe areas. Pollen productivity relative to Chenopodiaceae (R-Chenopodiaceae) was estimated using least-squares linear regression of pollen influx data against vegetation data and ERV model analysis of percentage pollen data against vegetation data. Rank order of R-Chenopodiaceae is consistent regardless of data set or analysis method. Artemisia has R-Chenopodiaceae values greater than 3, whilst R-Chenopodiaceae Nitraria is around 0.1 and R-Chenopodiaceae Poaceae is below 0.1. Our results provide useful information for quantitative reconstructions of paleovegation and paleoclimate in arid or semi-arid Asia.