摘 要: |
Establishing the relationship between surface pollen assemblages and related modern vegetation provides a bridge for reconstructing the palaeo-vegetation succession and related climate changes. Numerous contributions have demonstrated an inconsistency between the relative abundance values of surface pollen assemblages and corresponding modern vegetation for some taxa, which is attributed to differences in their pollen production, dispersal mode and preservation potential. Consequently, the concept of R-value was introduced as a correction coefficient to counterbalance this discrepancy. Unlike most of the complex forest and grassland ecosystems, desert vegetation with fewer dominant taxa provides a simpler model to demonstrate how to use the R-value to correct this deviation. Here, we propose a scheme of Rrel median values from modern desert vegetation types based on calculated R and Rrel adjustment coefficients of the dominant taxa using surface pollen and related modern vegetation data from 145 sample plots along an east-west desert transect in the eastern arid central Asia (ACA). These data revealed that 1) taking Nitraria as a reference, Chenopodiaceae, Artemisia and Ephedra are highly represented, while Tamaricaceae, Zygophyllaceae, Asteraceae (excluding Artemisia), Calligonum and Poaceae are poorly represented. 2) the pollen representation was constrained by their pollination strategies. For example, anemophilous plants (e.g., Ephedra, Artemisia and Chenopodiaceae) are mostly over-represented, while those of entomophilous taxa (e.g., Nitraria, Tamaricaceae, Zygophyllaceae and Calligonum) are underrepresented. The scheme and findings mentioned above cast a new light on the future of quantitative reconstruction of palaeo-vegetation succession in the ACA. |