THE VEGETATION CHENGES IN ULAN BUH DESERT SINCE THE LAST GLACIAL: POLLEN EVIDENCE FROM CORE WL10ZK-1

The paleo-vegetation changes of the Ulan Buh Desert since last Glacial are discussed according to the lithology, chronology and pollen analyses of the drill core WL10ZK-1.The high content of Typha pollen (up to 12%), and a quantity of Picea (up to 22.5%), Poaceae and Cyperaceae pollen from the bottom of drill core indicate that there was a lacustrine environment with steppe vegetation in the Ulan Buh Desert before 90 ka. Since 90 ka, xerophytic/halophyte herbs or shrubs such as Chenopodiaceae,Artemisia coupled with Tamaricaceae and Zygophyllaceae dominated the pollen from the middle of the drill core which indicates a desert vegetation environment occurred during the last glacial.During the phase of 8~7 ka, the UBD is dune-pond environment with steppe vegetation characterized by high percentage of Pinus and Artemisia.