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Pollen Assemblages Of Tamarix Cone Sedimentary Veinsand Paleoclimte Reconstruction In The Southern Margin Of Taklimakan Desret During Past About 400 Years

Posted on:2016-04-12Degree:MasterType:Thesis
Country:ChinaCandidate:F GuoFull Text:PDF
GTID:2180330461477248Subject:Physical geography
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Cele oasis is located in the middle part of southern margin of Taklimakan Desert(35°17′~39°30′ N, 80°03′~82°10′ E,ASML 1380m), with a warm temperate arid desert climate, the dry degree is extremely high, can reach 20.8. The Sunshine time is long, strong wind blew heavily there in Spring and Summer with more frequent sandstorms. The vegetation in this region is extremely poor, and the vegetation community types drab, single structure. In this paper, we through the study of Tamarix cone secion in Cele damagou, with the help of the WAPLS, we reconstruction of the process of climate change research area in the recent 400 years, and analyzes the basic characteristics climate background area evolution and its comparison with regional climate records, discusses the changes in plant communities of the research area.The research result shows that, in recent 400 years, the climate and vegetation evolution in the study area experienced three stages and nine sub-climate fluctuation:In 1590~1810, is the longest study period in given priority to with warm and dry, and accompanied by secondary cold warm and dry wet alternation: in the time of 1590~1650 and 1731~1794 is partial wet period, 1651~1730and 1795~1810 is warm and dry. Pollen type dominated by herbs and shrubs formed the desert-shrub vegetation mainly consisting of Artemisia, Chenopodiaceae, Gramineae and Tamarix. Quantitative recovery of the temperature is 10.5~13.4℃, average temperature is 12.0℃, precipitation is 19.7~60.1mm,average precipitation is 37.4mm. It is presumed that low temperature conditions during the little ice age and the North Atlantic Oscillation negative anomaly resulted in enhanced westerlies shifts southward strength, make the reach study area water bapor changes, prompted the stage of the relatively long period of drought.In 1811~1945, it was a transition changing from dry to cold and wet, the climatic fluctuation is obvious, experienced the alternation process obviously a cold and wet ~ cold and dry ~ warm and dry ~ cold and wet, of which 1811~1838 and 1859~1909 for the two stage of the cold wet period, 1839~1858 is the stage of a cold dry period,1910~1945,is also a warm dry period of the stage. The vegetation in this period is improved; form desert shrub vegetation major of Tamarix and Chenopodiaceae, the area is expand. the temperature is 9.8~13.4 ℃, average temperature is 10.9 ℃, precipitation is 19.7~83.8mm, average precipitation is 54.3mm.In 1946~2010, it is a relatively cold wet stage, the temperature has dropped in small increments, the precipitation increased obviously, the temperature is 9.5~12.2℃, average temperature is 10.3℃, precipitation is 37.8~98.5mm,average precipitation is 68.9mm. The vegetation types are mainly desert shrub, the area is further expand.There are a large number of crop pollens marked with big grain, which indicted human activities influence had increased gradually.Since the 1930 s, regional temperature fallen slightly due to the expansion of artificial oasis in this area,formed the obvious "oasis effect"; since the 1970 s, precipitation presents a downward trend in the study area, we think that is because in the basin, middle reaches the increase of water consumption, agriculture, industry, life caused by underground water level downstream continues to decline, soil water shortage, water plant growth condition deteriorated.
Keywords/Search Tags:Southern margin of Taklimakan Desert, Cele, Tamarix cone, pollen, Climat
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