Abstract: Based on 57 topsoil pollen samples collected from the south slope of Bogda Mountain, we analyzed the relationship between pollen assemblages and modern vegetation by means of quantitative ecology and discussed its ecological implications. According to principal component analysis (PCA) and cluster analysis (CA), the pollen samples were divided into five vegetation zones along the elevation, including shrub desert, semi-shrub desert, mountain steppe, mountain meadow steppe, and alpine meadow. The pollen assemblages differed significantly among vegetation zones, with Ephedra-Chenopodiaceae-Nitraria, Chenopodiaceae-Artemisia, Gramineae-Chenopodiaceae-Artemisia, Gramineae-Chenopodiaceae-Artemisia-Compositae-Cyperaceae, and Cyperaceae-Chenopodiaceae-Poaceae-Compositae-Rosaceae pollen assemblages dominating corresponding vegetation zones. By weakening the influence of Chenopodiaceae and Artemisia on other vegetation zones, topsoil pollen assemblages responded well to modern vegetation distribution. Pollen assemblage indicated the dry and wet conditions of soil and environment based on PCA. Cheno podiaceae, Gramineae, Artemisia, Cyperaceae, Ephedra, Compositae, Rosaceae, and Nitraria were the main pollen types, with high content and large variation, which could be used as important references for the reconstruction of paleoenvironment. Ephedra and Cyperaceae were well represented. Chenopodiaceae and Artemisia were super representatives, which interfered with the discrimination of the quantitative relationship between pollen content and modern vegetation in other zones. The content of Gramineae was reflected in the pollen spectrum of topsoil, but it was still less representative than that of grasses in modern vegetation. Shrubs, subshrubs, and upland herbs in arid habitats had obvious advantages in the simplified pollen spectrum of topsoil, revealing the aridity of natural environment and the sensitivity and fragility of ecosystems on the south slope of Bogda Mountain.

Key words: pollen assemblage, vegetation type, PCA, CA, Bogda Mountain.