Late Quaternary environment in Yunnan Province, China.

本项目自1992年以来由中日两国科研人员在中国云南省开展，作为青藏高原第6研究区“古环境变化”的“季风亚洲古环境变化”的一部分。本研究的目的是明确末次间冰期（约120000年）以来夏季西南风和冬季极锋的行为。，借助对易裂花粉、地貌和古土壤的分析。云南地处热带边缘，相对高度非常大，海拔170 ~ 6700多米，是最适合这一目的的省份。3年的研究结果表明：从现在的气候来看，我省东北部年降水量波动显著，与厄尔尼诺现象有明显的关系。利用纬度、经度和地形因子，估计了降水和气温的回归公式。冰川平衡高度在最西北的梅里雪山约为4800m，在其以南约300km的苍山约为3300m。在该省西半部，从红壤到棕色森林土的现代土壤和古土壤的垂直分布已经明确。尽管最古老的花粉样本大约是距今一万年。在4个采样点分析花粉带。在高山区和暖温带地区，植被与人类活动有一定的关系。

This project has been carried out in Yunnan Province in China both by Japanese and Chinese researchers since 1992 as a part of "Paleo-environmental change in Monsoon Asia" in the Study Area 6 "Change of Paleo-environment" in I.G.B.P.The aim of this study is to make clear the behavior of SW-monsoon in summer and polar front in winter since the last interglacial age, i.e.about 120,000 yrs.B.P., with the aid of analyzes of fissile pollen, landforms, palaeo-soils. Yunnan Province, located on the fringe of the tropical area with very large relative height from 170 to more than 6700m a.s.l., is the most suitable for this purpose.Results of our study for three years are as follows :As to present climate, the fluctuation of annual precipitation, which is clearly relate with EI Nino, is remarkable in the northeastern part of this province. Regression formulas were estimated for precipitation and temperature with the aid of latitude, longitude and topographical factors. Equilibrium elevation of the glaciers was about 4800m a.s.l. on Mt.Meili-xue-shan in the northwesternmost district and about 3300m on Mt.Cang-Shan ca.300km south of the former. Vertical distribution of modern soils and paleo-soils from red soil to brown forest soil has been made clear in the western half of this province. Although the oldest pollen sample was about 10,000yrs.B.P.pollen zones were analyzed in four sample points. In a high-mountain area and in a warm-temperate area, relation between vegetation and human impacts were found.