Western Hubei Dajiuhu Region Of The Last Glacial Vegetation And Climate

The environment today is evolved from Quaternary environment, and the future environment develops under the influence of natural and human factors. Researching the law of past climate evolution, investigating the coupling relationship between past human activities and environmental changes, is the international research hotspot today. Shennongjia Area, located in the middle and lower reaches of the Yangtze River, the south of the Qinling-Huaihe, humid and semi-humid transition zone, is strongly collision region of East Asian winter and summer monsoon circulation. Regional annual precipitation is basically controlled by the summer monsoon circulation. Dajiuhu Basin, located in the western of Shennongjia Area, surrounded by hills, is a mountain basin, accumulated sequential swamps. The natural state of the thick peat is the ideal working area of researching the evolution of the climate environment. Thus we choose the Dajiuhu basin as the ideal location of researching southwest monsoon and climate change in the Quaternary. We did pollen studies, with the hope of restoring Quaternary vegetation and ancient climate of the study area, and investigate the southwest monsoon's formation and evolution in order to provide new evidence for comprehensively understanding the Asian monsoon climate effects of the environment.Based on pollen records of the long 522cm core in the Dajiuhu Basin by the combination one of qualitative and quantitative means, we found that fossil pollen in the Dajiuhu Basin is comprised of mixed messages of vertical vegetational zone spectrum in high mountains around the studied area, but the pollen assemblage of B core can still distinctly disclose changes of vertical vegetation zone spectrum in mountains around Dajiuhu Basin. So palaeoclimatic evolutive history in the studied area can be speculated by the pollen assemblage.Since the last glaciation, the vegetation evolvement and climate change in Dajiuhu area go through the following three stages: Stage of the last glaciation riser, during the stage, there were temperate deciduous broad-leaved forest, the climate then was partial wet and cold ,and temperature was about 2-3℃lower than current; Stage of the last glaciation interriser, during the stage, the Dajiuhu area began to develop swamp in the basin with the herb Plant increasing, but the surrounding mountain forest is still developed. Abies/Picea forest retreated to the high altitude, the climate was cool and wet then, and the temperature was 1-2℃lower than current. During the last maximum glacial, the vegetation is temperate mixed broadleaf-conifer forest landscape, the climate was cold and wet, and temperature was 4℃lower than current.We speculate the causation of climate change since the last glacial in Dajiuhu basin, by comparing with the record of in the deep ocean and other continental records of global climate change. Climate information records of B section in Dajiuhu basin is respond to the solar radiation changes in the northern hemisphere and the changes of the East Asian Monsoon. Because of the location, the climate and environmental change reflected by Dajiuhu peat section are controlled not only by the East Asian monsoon, but also the East Asian monsoon including the Pacific and the Indian Ocean monsoon.