| The Qinling Mountains, as the geographical boundary of the southern and northern part of China, are mainly constituted by forest ecosystems and are sensitive to climate change.We select Pinus armandi growing at three elevations(1600~1800m,1800~2000m and2000~2200m) in the Huoditang forest region located on the south-facing slope of the Qinling Mountains as research objects. Based on the principles of dendrochronology, the chronologies of ring width,earlywood width and latewood were constructed and analysis the characteristic parameters of chronology. Responses of wood width to main climate elements(temperature and precipitation) ftom 1970~2012 were analyzed by correlation and response function methodologies. Determined the main climate factors affecting the tree growth in the region and to reveal the relationship between tree radial growth. Compared the differences of Pinus armandi ring width in the three elevationss to climate change.So that to provide references for forest management under climate change.The major achievements of this study are summarized as follows:1. Based on the principles of dendrochronology,we compared and analyzed the statistical characteristics of the STD chronologies of ring width,earlywood width and latewood width at three elevations(1600~1800m,1800~2000m and2000~2200m).The Mean Sensitivity,Express Population Signal and Signal to Noise Ratio are believable and reliable.Show that the chronologies contain abundant environmental information and suitable for dendrochronology study.2. The correlation analysis showed that Pinus armandi ring growth reflects the different levels of response relationships to climate change under different elevations: Temperature had a negative influence on ring width,while the precipitation had a positive influence on ring width. Precipitation in August of last year, April to May of current year had a significant positive effects on tree ring width grown in low altitude and the media altitude. Temperature in last August, April to June of current year showed a significant negative correlation on tree ring width; Pinus armandi grown at high altitudes had a negative correlation with temperature in September of last year and May of current year, showed a significant positive correlation with precipitation in August of last year, in May of current year. Comprehensive Correlation analysis showed: In the growth of Pinus armandi ring width is strongly influenced by precipitation in low altitude, and growth of Pinus armandi ring width is strongly influenced by temperature in high altitudes.3. Response analysis shows temperature and precipitation as the main climate limiting factors of Pinus armandi growth, the precipitation in to June are more important, precipitation in last year also had certain influence on tree growth. Temperature had negative influence on Pinus armandi growth just at the beginning of the growing season(April to May).Compared with the previous year precipitation influence on tree growth, the influence of the temperature is smaller. Through the annual ring width and precipitation and temperature response function equation, compared simulation values and measured values, simulated values is consistent represented response of Pinus armandi ring growth to climate.4. Analysis by characteristic year showed that climatic factors had a grate impact on the growth rings width of Pinus armandi.The lower temperature during spring and summer,the more precipitation in September and October of last year lead to the formation of Large rings.However,the higher temperature during spring and summer, the less precipitation during growing season of Pinus armandi from April to June lead to the formation of Narrow rings.In addition, the earlywood rate of Large rings(81.4%) was higher than that in the Narrow rings(72.5%), indicating the climatic factors play a greater role on the formation of Pinus armandi earlywood. |
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