Full-Text Search:
Home|Journal Papers|About CNKI|User Service|FAQ|Contact Us|中文
《Marine Geology & Quaternary Geology》 1990-03
Add to Favorite Get Latest Update

VEGETATIONAL AND CLIMATIC CHANGES IN THE LAST 11,000 YEARS IN QINGHAI LAKE——NUMERICAL ANALYSIS BASED ON PALYNOLOGY IN CORE QH85-14C

Kong Zhaochen Du Naiqiu (Institute of Botany, Academia Sinica, Beijing, China, 100044) Shan Fashou (Institute of Salt lake, Academia Sinica, Xining, China, 810008) Tong Guobang Luo Shaojie Fan Shuxian (Institute of Hydrogeology and Engineering Geology, Chinese Academy of Geological Sciences, Zhengding, China,050803)  
The Qinghai Lake is the largest inland saline lake in China. It stretches from 36°32' to 37°5' N and from 99°36' to 100°47' E, with a total area of 4635 square kilometres and an average water depth of about 19.15m. Topography varies from planal to (altitude of 3200m a.s.1) to high plateau and mountains (altitude of over 4000m). In Qinghai Lake region, annual mean precipitation is about 377-399mm, but because annual mean evaporation is 3.8 times of it, climate of Qinghai Lake region is semi-arid. Monthly mean temperature is 12.4°C in July, and the lowest is-12.7°C in January, so climate of Qinghai Lake region is cold. In accord with cold and semi-drought climate, vegetation zone of Qingdao Lake region shows high cold shrub, steppe and meadow, mainly composed of Gramineae, Compositae, Cyperaceae, Chenopodiaceae, and Zygophyllaceae etc. Gymnosperm is very poorly preserved, e.g. Ephedra and Sabina. Fern is also scanty. Only Pteridium aqulinum subalpine needle leaved forest, consisting of Picea, Finus and Betula, is distributed in the Qilian and Datun Mts, in temperate forest-steppe region of Huangshui, and also in valley of Huanghe River (the Yellow River) at an altitude of 2500-3l00m a.s.l. Served as the limit boundary of East Asia monsoon, climatic and vegetational changes are very sensitive in Qinghai Lake. Studies on the natural conditions and changes of the lake level are of great scientific and practical significance. This paper is based on a numerical analysis, including order cluster analysis, principal component analysis, moving average processing and regression equat-ion to discuss palynological datum of QH85-14C in the Qinghai Lake. Some conclutions are stated in the paper. 1. On the basis of the order cluster analysis, it is reasonable that pollen zone Ⅲ mentioned in the previous paper could be divided into two subzones (C1 and C2). And every pollen zone has its owns special characters of time sucoession of 14C dates and vegetation development stages. 2. On the numerical analysis, climatic changes in Qinghai Lake region since 11,000 years B. P. may be divided into three big stages, namely, Anath-ermal (11,000-8,000 or 7500 yr. B. P.), Hypsithermal (8,000 or 7,500-3,500 yr. B. P.)and Katethermal (since 3,500 yr. B. P.) 3. It is emphasized that vegetation and natural environment changed a lot in Qinghai Lake region during the 8,000 or 7,500-3,500 years B. P., when the vegetation was dominated by subalpine conifer forest in temperate zone consisting of Picea, Pinus and Betula; some broadleaf deciduous trees such as Ulmus, Quercus and a few ferns were also growing in Qinghai Lake region-According to distribution of forest vegetation in Hengduan Mountain and Qinghai Province in relation to hydro-thermal conditions (Li Wenhua et al, 1981-Zhou Xingmin et al. 1987), we preliminarily think out that the maximum te' taperature in July was about 2°C higher than present and, therefore, the min imum month was 8-11°C higher than today. The annual mean precipitation was 500mm or more. The increase of precipitation and decrease of evaporation, rise of the lake level and discovery of fossil wood, show that in the Hypsithermal interval, mixed needleaf everygr-een and broadleaf deciduous forests were widely distributed in Qinghai Lake region, climate was warmer and wetter than present time and annual precipitation was about 100mm more than today. So, numerical analysis of palynolo" gical datum is of great significance in geography, botany and anthropology
【Fund】: 国家自然科学基金资助项目
Download(CAJ format) Download(PDF format)
CAJViewer7.0 supports all the CNKI file formats; AdobeReader only supports the PDF format.
©2006 Tsinghua Tongfang Knowledge Network Technology Co., Ltd.(Beijing)(TTKN) All rights reserved