The Response Of Piceaschrenkiana Growth In The Source Region Of Aksu River To Climate And Climate Reconstruction

The location of the Aksu River basin is in the south-western part of the central Mount Tianshan and on the north-western edge of the Taklamakan Desert.It is a complex ecosystem made up of mountains,deserts and oases.The Aksu River is not only the highest flowing river on the southern slopes of Mount Tianshan,but also the river that currently flows into the Tarim River.It is the river that maintains its water allocation throughout the year,with an average annual natural flow of 80.6×108m~3.its final allocation to the Tarim River is 33.66 108m~3.Climate change in the Aksu River basin affects the water composition of the Tarim River.So from the perspective of the Aksu River as an international river,it is necessary to study climate change in the upper reaches of the Aksu River,which is also important for the conservation of water resources in the Tarim River basin.In this study,after the response of tree radial growth to climate change is analyzed and the collected samples are processed and analyzed,tree-ring technology and mathematical statistics are used to summarize the response and reconstruction of climate change.1.The ARSTAN program is utilized to generate three kinds of chronology(standardized chronology(STD),difference chronology(RES)and autoregression chronology(ARS)by using the sequence of the width of the rings in the Tagelake and Bozidun in the Aksu River region.After the chronological statistics are compared and statistically and analytically analyzed,the standardized chronology and the difference years of the wheel widths of Tagelake and Bozidun are reconstructed and the effective length of the regional chronology is 312 years(1706-2017).2.The correlation analysis revealed a correlation between the chronology and the climate of the growing season(May-September).Therefore,in this paper,regression analysis is utilized to reconstruct the mean maximum temperature in September,the mean temperature in May of the previous year,the mean minimum temperature in July of the previous year,and the mean precipitation in May for the Aksu River region.The reconstructed equations for the series all passed the test,which indicates that the reconstructed equations are reliable.The mean mean maximum temperature for September derived from the reconstructed equations is 29.56°C,the mean mean temperature for May of the previous year is 19.71°C,the mean minimum temperature for July of the previous year is 17.02°C and the mean precipitation for May is 8.73mm.3.The period 1706-2017 is divided into warm and cold periods based on the 11a sliding average of the reconstructed series values of the mean maximum temperature in September as well as using 25.964°C as the sliding average.The results indicate that the average temperature increased significantly in five periods:1786-1801,1816-1843,1876-1890,1904-1925 and 1981-2006.Of these,the longest period is the 28-year period from 1816 to 1843.In addition,the average temperature is 1.0°C higher in 1786-1801,1816-1843 and 1876-1890 than in the other periods,and the average maximum temperature is significantly lower in six periods,namely 1771-1785,1802-1815,1844-1861,1865-1875,1891-1903,and1926-1980.The lowest temperatures are recorded from 1926 to 1980 and lasted for 55 years.4.Ultimately,the reconstruction period is characterized by seven wet periods,which are 1731-1741,1750-1770,1789-1804,1807-1817,1841-1865,1891-1909 and 1988-2003.and four dry periods,which are 1771-1788,1818-1840,1866-1890 and 1945-1958.5.In this study,the maximum temperature experienced three positive mutations in 1762-1775,1852 and 1857-1872,respectively.It also experienced three negative mutations,which appeared in 1784–1790,1836–1843 and 1895–1897,respectively.The minimum temperature experienced four mutations,including three positive mutations,which appeared in 1928–1833,1893 and1957–1959.Moreover,it contained one negative mutation,which is from 1867 to1872.The average precipitation experienced nine mutations.Of these,four positive mutations occurred in 1864-1872,1768-1775,1852-1853 and 1912,respectively.There are five negative abrupt changes,which occurred in the years1879-1887,1749-1753,1784-1790,1836-1843 and 1895-1896.6.The high energy cycle of maximum temperatures is 8 to 10 years and it repeats itself over multiple time periods.In the early 20th century,the oscillatory period of around 16 years is more significant.In the mid to late 19th century,a 30-year oscillation cycle is significant,and the main cycle of average precipitation in the upper reaches of the Aksu River in May is 4 to 8 years,in which it is repeated.The 20th century is the more important period in which the energy of the 32 to 64 year oscillation period is high and its very significant in the mid 19th century and late 19th century.