PALYNOFLORAS OF THE DAJIUHU BASIN IN SHENNONGJIA MOUNTAINS DURING THE LAST 12.5KA

Located in northwest Hubei Province, Central China, Shennongjia region belongs to Wushan mountain range. It has a long geological history and a very high relief. Fifteen sporo pollen zones of the last 12 500 years are distinguished from three cores in Dajiuhu basin of Shennongjia mountains. They represent different stages of vegetation evolution. They are as fellows in ascending order: conifer and broadleaved mixed forest, conifer and broadleaved mixed forest with some Abies and Picea, conifer and broadleaved mixed forest dominated with deciduous broadleved trees, deciduous broadleaved forest with some conifer trees, deciduous broadleaved forest, evergreen and deciduous broadleaved mixed forest, deciduous broadleaved forest with some evergreen broadleaved trees, deciduous and evergreen broadleaved mixed forest, deciduous broadleaved forest with some evergreen deciduous broadleaved trees, deciduous broad leaved forest dominated with Quercus and Betula, deciduous broadleaved forest dominated with Quercus and Fagus, deciduous broadleaved forest dominated with Quercus and Betula , deciduous and evergreen broadleaved mixed forest, deciduous broadleaved forest with some evergreen broad leaved trees, conifer and broadleaved mixed forest dominated with broadleared trees. The vegetation succession has reflected the climate change in the period. During 12 500—10 600aBP, it was a cold and dry climate at the end of ice age. It changed gradually to a warm and wet climate during 10 600—7 400aBP 7 400—3 400aBP was the humidest and warmest stage in Holocene. It has been wet and warm with fluctuations since 3 400aBP.