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The Dendroclimatological Reconstruction And Comparative Analysis Of Climate Response Of Tree-ring Width In Different Altitudes Of Manasi River Basin

Posted on:2015-02-01Degree:MasterType:Thesis
Country:ChinaCandidate:Y Y QiFull Text:PDF
GTID:2250330422475394Subject:Physical geography
Abstract/Summary:PDF Full Text Request
The significance of the research work was not only a necessary complement tothe previous tree-ring studies of Manasi River Basin, but also provided the evidencefor long-term climate change in this River Basin.The paper established three different altitudes of tree-ring width chronologies(MNL, MNM, MNU). And it comparative analysis characteristic parameters of threechronologies. It analyzed correlation between three chronologies and Shihezimeteorological station(Total monthly precipitation, monthly mean temperature).Theaim of correlation analysis was to determine the effect of tree growth of climate limi-ting factors in this region. Used MNS chronology and average precipitation of fourweather stations in last July to June to reconstruction precipitation equation,and takeadvantage of " leave-one-out " to tested the reconstruction sequence. In the climaticvariation analysis, used respectively31-year moving average, standard deviation,running t test, power spectrum to analysis of variation in wet and dry, extreme,mutation, cycle characteristic of the reconstruction sequence.Conclusions of this paper as follows:(1) Through comparing parameters of the three chronology showed: expresspopulation signal, mean sensitivity,signal-to-noise ratio, mean correlation betweentrees, standard deviation, variance in first eigenvector decreased with increasingelevation; first-order autocorrelation of MNL chronology was least(r=0.281), butfirst-order autocorrelation of MNM chronology and MNU chronology were largethan0.5;the high frequency information decreased and with increasing elevation andthe low frequency information increased with increasing elevation.The temperaturewas the main climatic limiting factor for the MNU chronology; for the MNLchronology and MNM chronology, the precipitation played a positive role and thetemperature exerted indirect retroaction, and their correlation had obviousphysiological significance.(2) The test showed the reconstructed precipitation equation has better stability.The precipitation reconstruction results derived from the equation was reliable.(3)The precipitation reconstruction sequence had six wet stages and six drystages. The longest wet stage was1836-1883, lasting for48years.And the longest drystage was1754-1783, lasting for30years. This study area, a total of92partialdrought years, accounted for31.8%;38drought years,accounted for13.2%;5mostheavy years, accounted for2.8%. The5partial drought years and5drought years are documented in drought record in the history of the surrounding area.(4) The reconstructed precipitation had abrupt change in1757,1780,1807,1830.The precipitation changed from much to little around1757,1807and1830, while theprecipitation changed suddenly from little to much around1780.And themost significant change around1830. Among them1830which corresponds tosecondary mutation in the history of climate in1816and1830; in1757theprecipitation mutation correspondence which in Yili Prefecture of western Tianshanmountain, and1757and1780to verify the instability of the18th century again.(5) The reconstructed precipitation sequence had obvious change period of2.0~2.4a、3.3~3.8a、17.4a、48.0a、64.0a. Consistent between3.3~3.8a cycle and3~5a ENSO cycle;2.0~2.4a cycle was closed to the Quasi-Biennial Oscillation;48.0acycle,64.0a cycle corresponded with40~70a Significant variation cycle of theannual precipitation in Northern Xinjiang.
Keywords/Search Tags:Manasi River Basin, Picea schrenkiana et Mey, Tree-Ring Width, Response Analysis, Reconstruction of Climate Factor
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