Characteristics of the modern pollen assemblages from different sedimentary environments of the middle reaches of the arid Heihe region of Asia

Research into the surface soil pollen found within different sediments constitutes one important part of modern palynological analysis; however, such studies have not been carried out in the arid regions of Asia. In order to determine the main characteristics of the pollen assemblages of different sediments, 26 surface pollen samples were selected from five different sedimentary environments (sand dune, alluvial fan, wetland, floodplain and riverbed) found in three transverse sections in the middle reaches of the Heihe River. The results show that the five different sediment types have significantly different pollen assemblages: (1) sand dune: Chenopodiaceae - Artemisia - Nitraria - Poaceae; (2) alluvial fan: Nitraria - Chenopodiaceae; (3) wetland: Poaceae - Typhaceae - Chenopodiaceae - Artemisia; (4) floodplain: Picea - Cyperaceae - Chenopodiaceae - Artemisia - Asteraceae; and (5) riverbed: Picea - Cyperaceae - Polypodiaceae - Chenopodiaceae - Artemisia. The auxiliary functions derived from analyses of the principal components also indicates a significant difference between pollen assemblages for the five different sediment types. This established the veracity of these particular pollen assemblages representing these five different sedimentary environments, thereby improving the reliability of our research results. Those results provide the fundamental information required for any reconstruction of the region's paleovegetation and paleoclimate based on the pollen records found in different sedimentary environments.