黄土高原晚更新世的植被与气候环境

Vegetation and climate environment during the late Pleistocene in Loess Plateau, China

通过对黄土高原上陕西洛川、富县省等黄土剖面的地质调查、采样和孢粉分析 ,在曾被人们认为孢粉贫乏的黄土中分析出了大量孢粉 ,作出了黄土地层的孢粉浓度图式。结合其他地区数个剖面上孢粉组合的变化 ,阐明了晚更新世的植被与气候在时间上演变与空间上分布的规律 ,证明了各地植被在时间上的演变韵律十分相似 ,说明它们同受全球气候变化的控制 ;但在同一时期各地植被不尽相同 ,则是局部自然环境差异所致。

We have worked out quite a few pollens and spores from the commonly sporopollen poor loess, and plotted some concentration sporopollen diagrams of the loess strata for the first time. The evolution of vegetation and corresponding climate in time and space in the region has been brought to light by an analysis of the variation of sporopollen assemblages in many sections. There are three interstadials, warmer than present and two cooler stadials in the last interglaciation. They are correlated with the substages 5a, 5b, 5c, 5d and 5e of the deep sea oxygen isotopic curves. The climate in the stadials was severely cold, with a mean annual temperature 14℃ lower than the present. The climate in the interstadials was relatively warmer, with a mean annual temperature 3-9℃ lower than the present. The temperature in the stadials of the last interglaciation was the same as that in the interstadials of the last glaciation. The temperature in the interstadials was 1-3℃ higher than the present. It is known by comparing the sporopollen dliagrams from ten sections in the Loess Plateau that the changes of vegetation in time are very similar, implying that they were controlled by the same global climatic change. But the vegetation may vary from place to place due to changes of local natural environment. Vegetation during the late Pleistocene in the Loess Plateau is familiar with vegetation types of the warm-belt generally. When in the case of stadials of the interglaciation and interstadials of the glaciation, the alpine vegetation was descended to the land level, and in the stadials of the last glaciation, steppe or desert steppe landscapes were commonly seen.