甘肃平凉地区约80万年以来的植被与气候变迁

THE CHANGES OF VEGETATION AND CLIMATE IN PINGLIANG REGION，GANSU PROVINCE SINCE ABOUT 800 000 YR B.P.

将该地约８０万年以来的植被发展和气候变化历史划分为１４个大的阶段。其中距今约８０—７８万年、２０—１４万年、１０—１万年三个阶段的植被主要为荒漠草原，气候干冷；距今约７８—６４、５５—４６、１４—１０万年三个阶段植被主要为落叶阔林，气候温暖湿润；其它阶段的植被和气候处于上述二者之间。全新世早、中期，本区气候较现代温湿，晚期趋于温凉半干旱。

pingliang,loess,sporo-pollen,paleovegetation,climatic change Abstract In this paper,the stratigraphic sequence of the Ancun loess section in pingliang,Gansuprovince and the sporo-pollen assemblage of the samples taken from it were studied. The re-sults indicate that many times of changes of vegetation and climate in pingliang area occurredduring the past 800,000 yr B.P.The extent of vegetation changes is between deciduousbroadleaved forest zone and desert steppe zone;and climatic changes are between warm-hu-mid and cold-dry. The general treads of vegetation and dimatic changes since ca. 800,000 yr B.P. maybe divided into 14 large stages. There were three periods(i.e. around ca. 800,000 yr B.P ,200,000 to 140,000 yr B. P.,and 100,000 to 10,000 yr B. P.)in which climate wascold and dry,and vegetation was very sparse. The type of the vegetation was desert steppeconsisting of Artemisia,Chenopodiaceae,Nitraria,Ephedra Tamariceae etc. Three periods(i.e. ca; 780 ,000 to 640,000 yr B. P. ,550 ,000 to 460,000 yr B. P. ,and 140, 000 to100,000 yr B. P. )were warm and humid. Vegetation was very thick and its type was decidu-ous broadleaved forest composed of Quercus,Rhus,Tilia,Juglans and Betula etc. For theperiods of ca. 410,000 to 370,000 yr B. P. ,330,000 to 300,000 yr B. P,and 250, 000to 200,000 yr B. P., the the type of vegetation was temperate needle-broadleaved mixed for-est consisting of Quercus, Pinus,Betula and Juglans etc. ,witha warm and subhumid climate. From about 640,000 to 550,000 yr B. P,460,000 to 410,000 yr B. P. ,370 ,000 to 330 ,000 yr B. P. ,and 300, 000 to 250,000 yr B. P. ,the type of vegetation was dry steppe com-posed of Artemisia, Chenopodiaceae, Compositae and Gramineae etc. ,and the climate wascool and dry. In the early and middle Holocene,the climate of this area was warmer and more humidthan today. However, it tended to be mil-dcool and semiarid during the late Holocene.