摘要
本文主要依据青海湖具有^(14)C 年龄数据的 QH 85-14C 钻孔系统孢粉分析资料,将井深4.5m 岩芯所做的孢粉图式从下至上分为五个区域性孢粉带,进而论述了青海湖区11,000年来的植被曾经历了疏林草原(11,000—10,000年 BP)、森林草原(10,000年 BP)、森林(8,000—3,500年 BP)、森林草原(3,500—1,500竿 BP)和疏林草原(1500年前至今),反映的气候序列为凉干→温湿→温干阶段。
Qinghai Lake is the largest inland saline lake in China.it is situated in the northeastern part of the Qinghai Xizang Plateau. This paper is based on the information of the sporo-pollen assemblages of 47 samples from the drill core and surface samples.The general treads of vegetational and climatic changes since 11,000 years B.P.may be subdivided in ascending order as follows: In the first stage which corresponds to zone Ⅰ of the spore-pollen assemlage,the vegetation during the past of 11,000—10,000 years was represented by a temperate shrub,semi-shrub and steppe,consisting of Chenopodiaceae.Artemisia,Nitraria,Ephedra and Gramineae were pre- dominant.At tht same time,some subalpine conifers,Pinus,Picea and Betula,would grow b the side of rivers and lakes,the climate was warmer and wetter than that of the Late Pleisto- cene.Due to the rising temperature in this zone,the Pleistocene-Holocene boundary might be estimated at about 11,000 years B.P.The vegetation of the first stage belonges to temperate steppe with a few trees,In the second stage (Zone Ⅱ of pollen),the vegetation was characte- rized by a temperateforest steppe during this period of 10,000 to 8,000 years B.P.Forest area apparently increased and some broadleaf deciduous and need leaf evergrem trees,such as Quercus,Betula,Pinus and Picea,grew by lakes and on mountains At this time,the climate was warmer and wetter than that of the first stage,In the third stage (Zone Ⅲ) between 8,000 and 3,500 years B.P. The vegetation was composed of a temperate mixed broad-leaf deciduous and needle- leaf evtrgreen forest.The needle-leaf evergreen forest consisting of Picea,Pinus,Abies, Betula grew in temperate zone mountains.The climate was relatively warm and wet. The fouth stage (zone Ⅳ),the vegetation was dominated by shrub semishrub,dwaef semi- shrubs,steppe and semi-arbors.Some trees consisting of Betula,Picea,and Pinus decreased in number in the lake regions.Some subalpine cold temperature evergreen trees,such as Abies and picea disappeared from the lake region.This indicated that the climate was warmer and drier during tht past 3500—1500 years B.P.than the third zone.In the fifth stage (pollen zone Ⅴ),the vegetation comprised steppe and desert from 1500 years ago to the present time. Some arborealtrus such as Betula and Pinus were less increased about 500 years B.P.at this time the temperate and wet slightly,rose up.From the above analysis,it is clear that the Qinghai lake region has been confronted with the vegetational and climatic changes since I1,000 years B. P.Therefore,the palynoflora of the Qinghai lake has its significance in Geography and vegeta- tional history.
基金
本研究得到国家自然科学基金部分经费资助
关键词
全新世
孢粉分析
古植被
Qinghai Lake
Holocene
Palynoflora
Paleovegetation
Climatic Changes
