The Environmental Change Revealed By The Material Composition Of Tamarix Cone Sedimentary Veins In The South Region Of Taklimakan Desert

As an important composition of the earth surface system, the influence of desert’sclimate change on global ecosystem is remarkable. Taklimakan Desert is located in the TarimBasin of southern Xinjiang, deeply in the inland, it is the desret farthest from the ocean in theworld, its climate is dry with little rain, and strongly sandstorm activity. Tamarix with uniquephysiological structure under the harsh environment to survive, the sedimentary veins areformed by alternating deposition of litter layers and sand layers, contains a lot ofenvironmental information, which can restore the past environmental changes.This paper with the help of a variety of dating methods to determine the decade ofTamarix cones located in three different sites in Southern region of Taklimakan Desert, extractthe grain-size, organic matter, positive ion content,δ13C in Sedimentary veins, throughcorrelation analysis, regression analysis and other methods of mathematical statistics, choosethe appropriate proxy indicators, use kinds of proxy indicators and a single proxy indicator torestore various climatic elements, determine the most appropriate proxy indicator, combinemeteorological data of Southern region of Taklimakan Desert to rebuild the climate change inthis area for hundreds of years, The main conclusions are:(1) The sand layers and litter layers of Tamarix cone have a positive response to climatechange, including the sand material kurtosis, TN, positive ion (Ca2+) content and Δδ13Cvalues have strong correlation with various climate factors, which can be used to rebuild theclimate factors.(2)The Tamarix cone record the information of environmental change, with differentenvironment, the environmental information contented is different also. A sample site locatedin the desert, its water source mainly dependent on groundwater, therefore TN values andpositive ion (Ca2+)which is closely related to the moisture, failed to record environmentalinformation very well. And B sample site located at the downstream of the river, C samplepoint is located in the edge of the oasis, both moisture conditions are better than A sample site,the selected parameters recorded the environmental information.(3) The selected parameters of three sampling sites were not passed the correlation testwith precipitation. The climate of Southern region of Taklimakan Desert is arid with less precipitation, Tamarix mainly depends on groundwater, river water, ice-snow meltwater tosatisfy water demand, so the change of precipitation is not enough to cause a change ofenvironmental information contained in Tamarix cone.(4)Each climate factor reconstruction of the three sample point can select a parameter asregression factor, A sample site suitable for sand material kurtosis to restore temperature, forΔδ13C to restore wind velocity; B sample site suitable for Δδ13C to restore temperature andwind velocity, for the Ca2+content of previous year to restore relative humidity; C samplesite suitable for sand material kurtosis to restore temperature, for TN to restore wind velocity,for the Ca2+content of previous year to restore relative humidity.(5) The climate change trends of Southern region of Taklimakan Desert is from cold dryto warm wet, the wind velocity gradually decreases. A sample site: among which the periodsof1792~1812、1826~1840、1851~1982are cold periods, of1812~1825、1841~1850、1983~2010are warm periods; B sample site: among which the periods of1600~1671、1901~1980are cold periods, of1672~1900、1981~2010are warm periods; C sample site:among which the periods of1590~1710、1803~1847、1862~1879、1951~1966are cold periods,of1711~1803、1848~1862、1880~1950、1967~2010are warm periods. The results have agood correspondence with surrounding areas in Xinjiang.