Bortala River Basin Tree-ring Research And Climate Reconstruction

Analyzing the correlation between tree-ring width chronologies in the basin of Boertala River andclimatic information at Wen Quan and Bo Le Meteorological Station, and finding that the positiverelationship is significant between the tree-ring width chronologies at Ha Xia forest land and theprecipitation from October in the last year to July in the current year at Wen Quan Meteorological Station,the highest simple correlation coefficient is 0.549.However, For this two forest lands lies in the differentsituation ,San Tai forest land lies in more easterly situation than Ha Xia forest land. The former was perhapsinfluenced by f?hn effect is more obvious than the later .The temperature became mainly limited factorwhich influenced the growth of tree-ring . There is significant negative relationship between tree-ring widthchronologies at the other forest land-San Tai and the mean temperature from July to August at the samestation, the highest simple correlation coefficient is -0.563. Equations reconstructed were established usingthe filtered standardized chronologies of seven sampling sites at Ha Xia forest land and residualchronologies of eight sampling sites at San Tai forest land by means of stepwise regression, the results ofcrossing-test show that this two equations is stable and reliable. Then, finding that precipitationreconstructed has 5 dry stages and 6 wet stages in the basin of Boertala River, and has 2,3,4,12,29 and 43quasi dry-wet periods since the year 392.The precipitation reconstructed changes abruptly at 1730,1753,1778and 1831.And the mean temperature series reconstructed from July to August has 27 warm stages, and has11,12,13,22,27,40,72,93,94,95,146 and 147 quasi warm-cold periods since the year 461, themean temperature series reconstructed has abrupt changing years at 1696,1838,1842 and 1962. On the otherside, this article discussed the problem using tree-ring gray degree to reconstruct palaeoclimate. Byanalyzing the correlation between five kinds of tree-ring gray degree chronologies ( including the maximumgray degree, the minimum gray degree, the mean early-ring gray degree, the mean lately-ring gray degreeand the mean tree-ring gray degree) and precipitation and temperature since the year 1961 at Wen Quan andBo Le Meteorological Station, and finding that the correlation is more significant between standardizedchronologies of the maximum tree-ring gray degree and the precipitation from January to May at Wen QuanMeteorological Station, the highest simple correlation coefficient is 0.502 ,the significance is 0.0006. Ireconstructed the precipitation from January to May since about 100 years at Wen Quan MeteorologicalStation, using the standardized chronologies of the maximum tree-ring gray degree .And finding that theequation reconstructed is stable and reliable ,making use of methods of crossing-tested .From the result ofanalysis, finding that the precipitation series reconstructed has four dry stages and four wet stages from 100years at Wen Quan Meteorological Station, and has 11,12,22 and 23 quasi dry-wet periods .And theprecipitation series reconstructed did not occur evident abruptly change. From above, reconstructedpalaeoclimate using tree-ring gray degree was greatly important value.