西藏西部表土孢粉研究

A STUDY ON POLLEN IN SURFACE SOIL FROM THE WESTERN XIZANG

本文在西藏西部首次采用了稀释法研究了表土孢粉,并取得了比常规方法省时省力等效果;证明该法适用于大范围的荒漠地区研究。

During a period from 1989—1991, Sino—French research on the Western Kunlun and Karakorum Mts., the surface dust flux method was used for collecting pollen samples in surface soil in the Western Xizang. The method was initiated at the Laboratory of Palynology in Montpelier, which, fixing COUR'S sampler on the back of a car at a speed of forty kilometres per hour. The samples were collected in a certain distance along the road from Yecheng of Xinjiang to Shipuanhe of Xizang with a distance about 1000 km.The samples were chemically processed in laboratory. Pollen percentages and concentrations were analyzed and calculated. The conclusions are as following:1. In the pollen assemblage in surface soil. about 90% of them coincide with the regional vegetation. The dominant kinds of pollen are Chenopodiaceae, Artemisia. Gramineae, Gyperaceae, Ephedra, etc.2. The exotic tree—pollens are less than 6% generally and the most less than 10% of the total pollen quantity, which are mainly composed by Pinup, Betul Corylus, Aluns, Quercus, Juglans, Sabina, Populus, Acer, Salix Castanea. They possibly come from far places with west wind or north air current.3. The pollen assenblage in surface soil from alp—canyon desert is different from that from plateau desert. Pollen type of the former is iuxurient, and the lower the elevation is, the larger the pollen concentration, and the higher the pollen ratio between Chenopodiaceae and Artemisia is. The pollen assemblage in surface soil in plateau desert changes with latitude, Chenopodiaceae decreases from north to south, while Artemisia increases.4. In plateau desert, the pollen ratio between Chenopodiaceae and Artemisia can reflect humidity variation.5. The pollen concentration can roughly indicate the coverage of vegetation, except non-plant regions.It is the first time to research the relationships between pollen assemblage and vegetation and air current in China by flux method to sample the surface dust. The method has been proved to be suitable for wide desertic regions.