Reconstruction And Analysis Of The Dendroclimatology In The West Of Altay Region

According to tree-ring samples of Larix sibirica collected from eight sites in thewest of Altay region, in2009, using the method of spline function, the standardizedtree-ring width chronologies were developed. Correlation analysis indicated thatthere was significant correlation between the JDN chronology which located near thelower limit of the forest and the precipitation of last winter (r=0.523, α=0.0002),while there was positive correlation between the HLM chronology which locatednear the upper limit of the forest and the mean low temperature from June to July inthe under year growing season (r=0.422, α=0.004). By means of stepwise regressionmethod, the long-term sequence of precipitation was reconstructed from Decemberlast year to February current year, with an explained variance of42.4%. In the sameway, the long-term sequence of minimum temperature was reconstructed from Juneto July, with an explained variance of30.8%. It was verified that the reconstructedprecipitation and temperature series were reliable. Analyzing the reconstructed seriesshow that:(1) The growth of the Larix Sibirica in the west of Altay region was intensivelylimited by the precipitation (from December last year to February current year) andminimum temperature (from June to July). The result had distinct physiologicalsignificance. The reconstructed equation was stable by crossing-test.(2) In the250years, the winter precipitation in the west of Altay region had6wet stages and6dry stages. The longest wet stage was1937-1962, lasting for26years, and the longest dry stage was1854-1868, lasting for45years.In the250years, the minimum temperature in the west of Altay region had6warm stages and5cold stages. The longest warm stage was1856-1917, lasting for62years, and the longest cold stage was1810-1855, lasting for46years.(3) The reconstructed precipitation had abrupt change in1856,1916,1962,1987. The precipitation changed from little to much around1856and1987, while theprecipitation changed from much to little around1916and1962.The reconstructed minimum temperature had abrupt change in1858,1915,1962,1987. The temperature changed from high to low around1915and1962, while thetemperature changed from low to high around1858and1987.(4) As far as winter precipitation, there were47normal years,52dryish years,25dampish years,67dry years and59wet years. The wettest year was1860, and thedriest year was1932. As far as summer minimum temperature, there were177normal years,35warmish years,28coldish years,5warm years,5cold years. The warmest year was1860, and the coldest year was1854.(5) The reconstructed long-term precipitation sequence had3.4-3.8a,7.2-7.5a,7.9a,10.3a,16.6a,18.4a changing periods. The reconstructed long-term minimumtemperature sequence had no significant cycle.