Implication Of Paleovegetational And Paleoclimatic Changes In Ha'ni Lake, Jilin Since 5000 A .BP

Reconstruct the paleoclimate and paleoenvironment has been the hotspot of the word.The human beings'history has been recorded in character since 5000 years S- tudies of climate change during past 5000aBP take an very important part in the hu- man beings'daily life.The vegetation is the best indication to the climate changes in the nature, The research of spores and pollens was considered as one of important means to study on the history of vegetation and paleoclimate,paleoevironment .According to the spore pollen analysis resulted from 85 core samples from Ha'ni Lake,the average year was 60,the history of vegetation and environment can be div- ided into four stages as follows: 1. Stageâ… (5112-3784aBP): The warm-inclined br- oadleaved trees predominated in this stage, the climate was warm and wet. 2. Stageâ…¡(3784-1380aBP);The coniferous trees predominated the whole stage, the hydrop- hytic herbaceous plants disappeared, the climate changed into cold and dry. 3. Stageâ…¢(1380-994aBP):The percent of coniferous trees continued to increase and hydro phytic herbaceous plants became less, which suggested that the climate is colder and drier . 4. Stageâ…£(994-0aBP): The diversity of the plants was great, the pollen sedimentation rate of hydrophytic herbaceous plants was obviously increas- ed, so the climate changed into more humid.