新疆东部托勒库勒湖流域表土花粉初步分析

THE PRELIMINARY STUDY OF THE SURFACE POLLEN FROM TUOLEKULE LAKE BASIN,EASTERN XINJIANG,CHINA

研究现代表土花粉谱与植被及气候的关系对正确解译地层花粉所指示的植被演化历史以及生态环境具有重要意义。本文首次选取新疆东部托勒库勒湖盆地开展现代表土花粉与植被关系的分析。结果发现各个植被带的花粉组合与其主要植物成分具有良好的对应关系。湖泊表层样品的花粉组合是区域植被组成的综合反映;莎草科花粉主要出现在草甸中;禾本科是湖边草原中重要的花粉类型,该科花粉呈现出明显的低代表性;藜科和蒿属是荒漠草原植被中两种最主要的花粉类型;白刺属主要出现在低洼平坦的湖边,该属植物的分布与水源有着密切的关系;在采自砾漠的样品中,菊科、麻黄属成为两种最主要的花粉类型,这对解释地质时期该湖地层中两种花粉组合所指示的植被演化和生态意义具有重要作用。

The relationship between modern pollen assemblage and its vegetation zone is greatly important to accurate interpretation of the environment and its history of vegetation evolution when using fossil pollen. In this paper, we first select the Tuolekule Lake basin to carry out the study of relationship between modern pollen assemblage and their vegetation zones. The Tuolekule Lake （ 43 °23 ＇55＂N, 94°14＇41＂E ） , located at Yiwu County, eastern Xinjiang Province,China,and the attitude is about 1892m a. s. I. The surface area of the lake is ca. 23km2 ,with maximum depth water more than l m. At present, no major rivers drain into Tuolekule which is instead recharged by groundwater and by small ephemeral rivers originated from springs. The lake＇s region belongs to the cold-temperate and continental climate. The annual average temperature is 3.5℃, annual precipitation and evaporation are 102. lmm and 2300mm, respectively. We analyze total 23 pollen samples, all of which come from six different zones. That is, seven of them are the lake＇s mud samples, others （ 16 samples） come from meadow, steppe, desert, Gravel/Gobi, and desert-steppe around piedmont. The results show that the pollen assemblages have a good relationship with their vegetation zones. For example, pollen assemblages of the lake＇s mud were major reflect of the vegetation composition of the whole lake basin. Cyperaceae pollen was the most important element in the meadow; however, we also found that the percentage of Composite pollen is especially low in this zone. Gramineae pollen mostly appears in the steppe of the lake basin. The result also shows a low R value of Gramineae pollen when comparing with the percentage of Gramineae plant in the vegetation zone. However, Chenopodiaeeae pollen shows a high R value when comparing with its percentage in this vegetation zone. Chenopodiaceae and Artemisia pollen major appear in the desert and/or steppe-desert. Nitraria pollen major appears in the low area of the lake basin, and it has a close-relationship with the underground water of the lake basin. In the gravel/Gobi, Compositae and Ephedra pollen is the two most important pollen types,the pollen assemblage of which was crucial to accurate interpreting the environment and the history of vegetation evolution from the fossil pollen of this lake.