Modern pollen distribution and its relationship with environmental difference in southwestern China

Abstract

Quantitative relationships between pollen and vegetation in the Longitudinal Range-Gorge Region (LRGR) are studied based on the pollen records of 35 surface soil samples and 7 vegetation quadrates. The spatial distribution of the pollen and the relative control of environmental factors are analyzed. Results are: (1) The R values, which designate the representation of pollen to vegetation, indicate a good quantitative relationship between surface pollen assemblages and local vegetation. (2) Significant differences in diversity of pollen flora, pollen amounts, major taxa, and vegetation between the east and the west sides of Ailao Mountain, an important geographical dividing line in LRGR, are recognized. (3) Obvious spatial differences of pollen assemblages are relevant to different regional topography and climatic conditions. These results suggest that the spatial differences between pollen assemblages would be caused by the different pattern of hydrothermal condition in the unique topography of the LRGR. The barrier function of the vertical mountain ranges, especially by the Ailao Mountain, may be a main factor in such environmental differences. Two separate monsoon circulations occurring in Pacific and Indian oceans result in different hydrothermal characteristics causing the regional differentiated patterns in the pollen assemblages in the study area.