The palynofloras and climate change in dajuhu basin of Shennongjia Mountains during the last 12500 a.B.P

It is very important to study the relationship between plantation susscssion and climate change of late Quaternary. Fifteen palynofloras during the last 12 500 years are distinguished from the sidiments in Dajiuhu basin of Shennongjia mountains. They represent different stages of plantation evaluation, which are as follows 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 Betula and Quercus , deciduous broadleaved forest with some conifer trees, deciduous broadleaved forest dominated with Quercus and Betula , evergreen and deciduous broadleaved mixed forest, deciduous broadleaved forest with some evergreen broadleaved trees, deciduous broadleaved and evergreen broadleaved mixed forest, deciduous broadleaved forest, deciduous broadleaved forest domminated with Fagus and Betula , deciduous broadleaved forest dominated with Quercus , deciduous broadleaved forest dominted with Quercus and Betula , evergreen and deciduous broadleaved mixed forest, deciduous broadleaved forest with some evergreen broadleaved trees, conifer and broadleaved mixed forest. These palynofloras also indicate the climate change. It has a transit climate during 12 500～ 7 400 a.B.P. Annual mean temperature (AMT) and Annual mean precipitation (AMP) increase quickly. At the end of Pleistocene, AMT and AMP are 4.5～6.1℃ and 160～ 195 mm lower than that of at present respectively. It is very hot and humid during 7 400～ 3 300 a.B.P,AMT and AMP are 1.1～3.9℃ and 35～125 mm higher than that of at present respectively. It is warm and wet during the last 3 300 years. AMT and AMP fluctuate around the present value.