晚更新世晚期以来昆仑山垭口区的植被与环境

昆仑山垭口区小南川剖面和雪水河热水剖面的孢粉分析揭示了该区４４０００ａＢ．Ｐ．以来的植被演替和气候变化。４００００ａＢ．Ｐ．前，推测昆仑山垭口区为典型的灌木荒漠植被，气候极端干燥。４００００－３００００ａＢ．Ｐ．，气候稍有好转。３００００－２４０００ａＢ．Ｐ．为草原荒漠，降水增加。２４０００－１８０００ａＢ．Ｐ．为末次冰期极盛期，气候干冷。１８０００－１３０００ａＢ．Ｐ．气候凉偏干。１３０００－８０００ａＢ．Ｐ．气候凉干。８０００－６０００ａＢ．Ｐ．为全新世温暖期，但由于植被的滞后现象，本区仍为草原荒漠景观。６０００－５０００ａＢ．Ｐ．，本区可能也存在着中全新世的降温事件。５０００－３０００ａＢ．Ｐ．在全新世大暖期的影响下，小南川附近的植被演变成温性草原植被，并有人类的放牧活动。３０００ａＢ．Ｐ．以后，气候变凉，草原迅速地演变为灌木和小乔木荒漠植被，其中３０００－１０００ａＢ．Ｐ．为凉干时期，１０００ａＢ．Ｐ．以后，可能有过一段凉湿时期。

VEGETATIONAL AND ENVIRONMENTAL CHANGES OF KUNLUN MT. PASS AREA SINCE LATE PLEISTOCENE

Analyses on pollen of the Xiaonanchuan and Reshui Sections reveal the vegetational succession and climatic changes of the Kunlun Mt.Pass area since 44KaB.P.There was a typical desert vegetation with a very cold and dry climate before 40KaB.P.Between 40.30KaB.P.,the climate slightly improved and the precipitation increased with steppe and desert vegelation during 30-24KaB.P.However,the climate became very cold and dry again with a desert vegetation developed during the Pleniglacial of the last glaciation, and it became cold and arid during 18-13KaB.P.There was still a steppe and desert vegetation during the Holocene Hypsithermal as the vegetation lag.There might be a cold event in the period of the Middle Holocene.Under the influence of the Holocene Hypsithermal, the vegetation near Xiaonanchuan was transformed from steppe and desert vegetation into temperate grassland,a good place for pasture.After 3KaB.P.,the climate became cool,and the vegetation changed rapidly from temperate grassland to desert with shrubs.In this period,it was cool and arid during 3-1KaB.P.and cool and moist after 1KaB.P.