柴达木盆地表土孢粉与植被的关系

Relationship between surface pollen and vegetation in the Qaidam Basin

通过对柴达木盆地124个样点的表土孢粉分析和植被样方调查,研究了盆地表土孢粉与植被的对应关系。结果表明:柴达木盆地的表土孢粉组合能较好地反应当地植被特征,但是在具体的科属组成上有差异。藜科、蒿属、麻黄属等花粉矫正系数R值大于1,具有超代表性;柽柳属、菊科等花粉矫正系数R值小于1,具有低代表性,但对植被具有一定指示意义;禾本科和白刺属花粉在大多数样点具有低代表性,但禾本科花粉在建群种样点、白刺属花粉在盐碱区都具有适中代表性。主要科属花粉百分比与植被盖度之间具有一定相关性,禾本科、莎草科、菊科、柽柳属的相关性较高,可以建立相应函数关系。盆地西部的无植被区仍有相当含量的花粉,主要为藜科、蒿属、麻黄属、松属等超代表性花粉。盆地蒿属与藜科花粉比值(A/C)呈东南-西北递减趋势,与盆地由东南-西北逐渐干旱的环境特点很好对应。主要草灌木表土花粉数据的主成分分析表明,该区花粉组合主要受水文和土壤盐碱度等因素控制。

In order to investigate the relationship between surface pollen and modern vegetation,a total of 124 surface pollen samples collected from the Qaidam Basin were analyzed.The results show that the relationship between the pollen assemblages of surface samples and the main vegetation types was significant;however,the pollen assemblages of surface samples did not fully reflect the composition of families and genera.The R values of Chenopodiaceae,Artemisia,and Ephedra were greater than 1,indicating that these three pollen types are highly representative.The R values of Tamarix and Compositae were less than 1,indicating that the representativeness of these two pollen taxa is low for their coverage.Further,Gramineae and Nitratia representation was low in most samples.However,Gramineae had better representativeness in areas where it was the constructive or dominant species in plant communities,and Nitraria had moderate representativeness in alkaline regions.There was a certain correlation between the pollen percentage of main families and vegetation coverage,and higher correlations could be established for Gramineae,Cyperaceae,Compositae,and Tamarix.Pollen in non-vegetation regions was mainly composed of Chenopodiaceae,Artemisia,and Ephedra.The ratio of Artemisia to Chenopodiaceae pollen shows a decreasing trend from southeast to northwest,corresponding closely with the environmental characteristics of the basin,which gradually becomes drier from southeast to northwest.Principal component analysis of the main herbaceous and shrub pollens showed that the pollen distribution in this area is mainly controlled by hydrological conditions and soil pH.