黄河兰州段河水搬运花粉与累积花粉组合特征初步研究*

对从2011年9月至2012年6月在黄河兰州段采集的24个水样进行了孢粉分析,并探讨了河流搬运花粉组合随时间变化的特征以及累积花粉的组合状况。结果表明,河流中花粉组合和花粉浓度随时间具有明显的变化,春夏时段花粉组合以榆属、杨属、柳属和桦属等乔木花粉为主,秋冬时段以蒿属、藜科等草本花粉为主,且花粉浓度和河流含沙量有较好的正相关关系。根据河水流量与花粉浓度积分计算得出样品采集时段的累积花粉通量,其组合特征与各时间点的花粉组合具有明显的差异,表明单个时间节点花粉组合由于影响因素较多不能够反映流域植被状况,而累积花粉组合可以指示泥沙和花粉源区的植被状况。本研究中黄河兰州段河水搬运花粉可能指示黄河兰州段以上至刘家峡水库之间黄土区的植被情况。

Preliminary study on assemblages characteristics of waterborne pollen and accumulated pollen from the Yellow River at Lanzhou station

Twenty-four water samples were collected from the Yellow River at Lanzhou station from September in 2011 to June in 2012. Based on the pollen analysis, the temporal change characteristics and accumulated pollen features of the waterborne pollen were discussed. The result shows that pollen assemblages and pollen concentration have obvious changes over time:Ulmus,Populus,Salix and Betula are the major components of the pollen assemblages in the spring and summer;and Artemisia and Chenopodiaceae are main species in the autumn and winter. Pollen concentration has a positive correlation with waterborne sediment concentration. There are obvious differences between pollen assemblages of individual samples and the accumulated pollen assemblage,and pollen assemblages of individual samples cannot reflect regional plant communities. Accumulated pollen assemblage can basically represent the vegetation status of loess area from Liujiaxia reservoir to Lanzhou where it is suggested to be the main pollen and sediment source area in this study site.