ENVIRONMENT EVOLUTION INFERRED WITH PHYTOLITHS FROM LACUSTRINE DEPOSITS OF XINGYUN LAKE

The 85 cm core of XY-1 was obtained from the Xingyun Lake, in the central Yunnan Province, southwest China. The objective of the project was to get the geological record of environment change and disclose the relationship between human activities and the natural factors. 22 samples were used for phytolith analysis. Many types of phytoliths were found in the samples, showing a good relationship with the environment evolution. Results show that four climatic stages can be recognized according to the records since about 160 a, including the cool period before 1920s, the warm period between 1920s to mid-1950s with the warmest period in 1940s', the cool period between mid-1950s to 1970s and the warm period in 1980s. Vegetation evolution can also be restored according to phytolith records. Human activities were also recorded, such as the denudation and over reclamation during the end of 1950s. The phytolith are sensitive to the environmental changes. However, the increasing human activities may effect the record of the change in the nature. More detailed work should be done for better understanding the relationship between environment evolution and human activities.