干旱区生态环境知识资源中心

Aim This modern pollen-rain study documents the spatial and quantitative relationships between modern pollen and vegetation in Mongolia, and explores the potential for using this relationship in palaeoclimatic reconstructions.

Location East-central Mongolia.

Methods We collected 104 pollen surface samples along a south-north transect across five vegetation zones in Mongolia. Discriminant analysis was used to classify the modern pollen spectra into five pollen assemblages corresponding to the five vegetation zones. Hierarchical cluster analysis was used to divide the main pollen taxa into two major groups and seven subgroups representing the dry and moist vegetation types and the main vegetation communities within them.

Results Each vegetation zone along the transect can be characterized by a distinctive modern pollen assemblage as follows: (1) desert zone: Chenopodiaceae-Zygophyllaceae-Nitraria-Poaceae pollen assemblage; (2) desert-steppe zone: Poaceae-Chenopodiaceae pollen assemblage; (3) steppe zone: Artemisia-Astertype-Poaceae-Pinus Haploxylon-type pollen assemblage; (4) forest-steppe zone: Pinus Haploxylon-type-Picea-Artemisia-Betula, montane forb/shrub and pteridophyte pollen assemblage; and (5) mountain taiga zone: Pinus Haploxylon-type-Picea-Poaceae-Cyperaceae, montane forb/shrub and Pteridophyte pollen assemblage.

Main conclusions Based on the ratio between the major pollen taxon groups and subgroups, we propose two pollen-climate indices that represent the precipitation and temperature conditions in the study region. When plotted along our south-north transect, the moisture indices (M) and temperature indices (T) mimic the regional gradients of precipitation and temperature across Mongolia very closely. These pollen-climate indices can be used for palaeoclimatic reconstruction based on fossil pollen data.