Late Quaternary environment in Yunnan Province, China.

这项研究是中日两国科学家1992年以来在云南中国地区进行的，是中日两国在青藏高原6区“古环境变化”中的“亚洲季风古环境变化”研究的一部分。本研究的目的是通过对末次间冰期(约12万年)以来的夏季西南季风和冬季极锋的分析，结合裂变孢粉、地貌和古土壤的分析，弄清夏季西南季风和冬季极锋的行为。云南省地处热带边缘，相对高度从170米到6700米以上，是最适合这一气候变化的地区。3年来的研究结果表明：就当代气候而言，云南省东北部地区年降水量波动显著，与厄尔尼诺现象有明显关系。利用纬度、经度和地形因子，估算了降水量和气温的回归公式。冰川的平衡海拔约为4800ma.s.l。在最西北部的梅里雪山上，在前者以南约300公里的苍山上约3300米。明确了从红壤到棕林土的现代土壤和古土壤的垂直分布。虽然最古老的花粉样本约有10000年，但在四个采样点进行了花粉带分析。在高山地区和暖温带地区，发现了植被与人类活动的关系。

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.