The Preferred Application Of Environmental Proxies Of Tamarix Cone In Environmental Change Research In The Southern Source Of The Taklimakan Desert

The Taklimakan Desert is located in the southern part of Xinjiang Uygur Autonomous Region.It has the Pamir Plateau in the west,the Lop Nur in the east,the Tianshan Mountain in the north,the Altun Mountains,the Kunlun Mountains and the Qinghai-Tibet Plateau in the south.The terrain is high in the southwest and low in the northeast.It is surrounded by mountains on three sides.The center of the Eurasian continent is far from the ocean,making it the most arid region in Asia.The southern source of the Taklimakan Desert has many oases and is the core of the arid region.Studying the environmental changes in the southern source of the Taklimakan Desert is important for studying the environmental changes in the arid region,but the lack of traditional information carriers due to environmental changes limits the study of environmental changes in the region.Tamarix sediment veins formed by alternating deposition of litter layers and sand layers,just like the annual rings of trees,it is a high-resolution dating method,and it also contains rich information on paleoclimate environment,which has become an effective means of studying environmental evolution in arid regions.This paper takes Minfeng County and Cele County in the southern source of the Taklimakan Desert as the research area,and takes the typical Tamarix sediment veins in the three areas of Andir,the Andir Ranch and Damagou Town as the research object,and analyzes and processes the field survey and laboratory experimentsasthe research method,Comprehensive optimization and analysis of sand grain-size,the organic matter carbon and nitrogen,positive ion content in Tamarix fallen leaves,stable carbon isotope and stable oxygen isotope contained in the Tamarix sediment veins.Establish a correlation between climate environmental indicators and meteorological data,using the stepwise regression method,the sequence of climate change in the southern source of the Taklimakan Desert has been reconstructed for hundreds of years,and compared with single indicator reconstruction result,related area research result,and standardized sequence research result,the sequence of climate environment change in the southern source of the Taklimakan Desert is obtained.The main conclusions are:?1?The litter layers and sand layers responded positively to environmental changes.The correlation between climate proxy index and annual average temperature is summarized as follows:standard deviation>kurtosis>sorting coefficient>skewness>Mg²⁺>K⁺>mean grain size>??¹³C>median particle size>Na⁺>C/N>TN>TOC>Ca²⁺>?¹⁸O;sand grain-size?positive ion content in Tamarix fallen leaves and??¹³C are sensitive;The annual mean temperature and standard deviation,kurtosis,Mg²⁺and K⁺were all tested by confidence.The correlation between climate proxy index and annual average precipitation is summarized as:skewness>mean grain size>median particle size>sorting coefficient>standard deviation>kurtosis>TOC>??¹³C>Na⁺>Mg²⁺>K⁺>Ca²⁺>C/N>TN>?¹⁸O;sand grain-size?positive ion content in Tamarix fallen leaves and??¹³C are sensitive;The average annual precipitation and skewness were tested by confidence.The correlation between climate proxy index and annual average wind speed is summarized as follows:standard deviation>sorting coefficient>??¹³C>kurtosis>K⁺>Mg²⁺>C/N>skewness>TN>Na⁺>mean grain size>median particle size>TOC>Ca²⁺>?¹⁸O;sand grain-size???¹³C and positive ion content in Tamarix fallen leaves are sensitive.?2?The average value of the correlation between the climate climatic indicators and the annual average temperature,annual average precipitation,and annual average wind speed at the sampling point of the ancient city of Andir is known as:kurtosis>skewness>standard deviation>sorting coefficient>??¹³C>Mg²⁺>K⁺>Na⁺>mean grain size>median particle size>?¹⁸O>TOC>C/N>Ca²⁺>TN;For areas with a large impact on natural factors in the arid zone,reference can be made to the ancient city of Andir.The preferred indicators are sand grain-size,??¹³C and positive ion content in Tamarix fallen leaves.Samples of Andir Ranch:kurtosis>skewness>standard deviation>??¹³C>mean grain size>sorting coefficient>median particle size>C/N>Na⁺>TOC>K⁺>TN>Mg²⁺>Ca²⁺>?¹⁸O;Areas in the arid zone that are both controlled by natural conditions and affected by activities can refer to Andir Ranch;The preferred indicators are sand grain-size and??¹³C.Damagou sampling point:sorting coefficient>K⁺>Mg²⁺>standard deviation>median particle size>mean grain size>TN>C/N>kurtness>skewness>Na⁺>??¹³C>TOC>?¹⁸O>Ca²⁺;For areas with a greater impact on human activities in the arid zone,refer to Damagou;The preferred indicators are sand grain-size and positive ion content in Tamarix fallen leaves.?3?In the reconstruction of air temperature,precipitation and wind speed,only sand grain-size,positive ion content in Tamarix fallen leaves,TOC and??¹³C factors in the Tamarix sediment veins enter the stepwise regression equation,which can be used as a reference for future climate analysis and reconstruction.The data of sand grain-size,positive ion content in Tamarix fallen leaves,TOC and??¹³C,especially sand grain-size and positive ion content in Tamarix fallen leaves perform well,which not only reduces the workload,but also better represents the climate of the southern source of the Taklimakan Desert.?4?The sampling point of the ancient city of Andir can reconstruct the annual average temperature with kurtosis,the average annual precipitation can reconstruct by skewness.the annual average wind speed can be reconstructed by??¹³C and Na⁺.Samples of Andir Ranch can reconstruct the annual average temperature with standard deviation,median particle size,K⁺.the average annual precipitation can reconstruct by TOC.the annual average wind speed can be reconstructed by??¹³C.Damagou sampling point can reconstruct the annual average temperature with the K⁺.the average annual precipitation can reconstruct by median particle size.The annual average wind speed can be reconstructed by sorting coefficient.?5?The climate change sequence in which multiple indicators work together is more advantageous than the climate sequence reconstructed by a single indicator.According to the normalized sequence,it is known that the environmental change in the Southern region of the Taklimakan Desert region is from cold and dry to warm and wet:1590¹630 is the warm and wet period,1631¹790 is the cold and wet period,1791¹819 is the warm and dry period,1820¹834 is the warm and wet period,1835¹887 is the cold and wet period,1888¹933 is the cold and dry period,1934¹988 is the warm and dry period,1989-2010 is the warm and wet period,and the wind speed is weakening after the 1990s.