新疆博斯腾湖表层沉积物的孢粉分析

通过对新疆博斯腾湖的表层沉积物孢粉的分析, 探讨了干旱区大型湖泊中表层沉积物孢粉与周围植被的关系以及孢粉在湖泊中的分布和传播规律. 研究发现, 博斯腾湖表层沉积物中孢粉主要是来源于周围荒漠植被中的藜科、蒿属、麻黄等植物以及湖泊四周浅水地带生长的香蒲等水生植物. 藜科、蒿属、麻黄等花粉的传播过程主要受大风作用的影响, 而且百分比含量在整个湖盆中的分布比较稳定, A/C值能够反映区域目前的干旱状况; 香蒲等水生植物花粉的百分比含量主要受其母体植物分布的影响. 云杉花粉在河口区域的相对高百分比含量表明其河流传播特征; 云杉花粉在湖泊中的低百分比含量与整个流域的植被及其分布状况以及区域的气候条件有关; 云杉花粉具有超代表性. 近河口湖泊表层样品孢粉组合受河流和近岸植被的影响较大, 但距离超过2 km以后湖泊沉积花粉百分比含量较为稳定. 孢粉的质量浓度分布显示, 孢粉在湖盆中的分布有比较强的趋中性. 博斯腾湖中部沉积物孢粉序列能够很好记录区域的植被变化历史和环境演化特征.

Modern Pollen Analysis of the Surface Sediments from the Bosten Lake, Xinjiang, China

Lake sediments provide an opportunity to understand vegetation history in the arid or semi-arid regions. However, the interpretation of such records is itself hampered by a lack of information relating to differential pollen production, transportation, deposition and preservation. So, it is important to understand the modern process of pollen sedimentation and its environmental significance. In this paper, result is presented of a study on modern pollen from surface sediments in the Bosten Lake, the largest inland freshwater lake in Xinjiang Uygur Autonomous Region, Northwest China. It is suggested that Chenopodiaceae and Artemisia, which might be transported by the strong wind, are dominant in the lake. These two species have a stable percentage in the whole lake basin, except for an area 5 km close to the outfall. A/C, the ratio of percentage of Chenopodiaceae and Artemisia, is about 0.5 and can reflect the dryness around the lake. The distribution of pollen/spore from hydrophyte, such as Typha, seems to be affected by the location where parent plants grow. Picea is over-representative and mainly transported by water, with a low percentage controlled by the vegetation situation and precipitation, as compared to that in the Shiyang River drainage. The sedimentation focusing increases the concentration of pollen grains in the central part of the lake basin, showing that the pollen spectrum of the core samples from the central part of the Bosten Lake can truly record the vegetation change history of the region.