Tree ring chronologies have been used as a very good replaced reference for the climate flux in the research. Many academicians have already studied the climate change in the dry area of west and north China by using tree rings. Only a few works have been done in tropical and subtropical regions due to relative low sensitivity there.There are many ecological researches in Dagangshan State Forest Ecosystem Research Station in Jiangxi Province, it's very important to rebuild the history climate for the study in this area. So we selected the area for the study object.
According to tree-ring samples of Pinus massoniana from four sampling points in Dagang Mountain area, we have established a comprehensive tree-ring chronology in this region. The tree-ring width series were measured with LINTAN5 and its software TSAP (time series analysis presentations), and the measured tree-ring series were crossdated and quality-controlled with the software COFECHA. Using the ARSTAR software to get off the growing trend of trees, and then develop tree-ring width chronology. There are three different kinds of chronology were established, including standard chronology (STD), residual chronology (RES) and arstan chronology (ARS). Comparison of chronology statidtics among these chronologies indicates that STD contains more climatic signal.Statistical analysis of STD showed mean series inter-correlation of 0.52, mean sensitivity of 0.27, and signal-to-noise of 25.70. And the tree-ring chronology was fit for the dendroclimatologic study.
After conducting an analysis to the related and response relationship between radial growth of Pinus massoniana and climate change-related factors, we found that the tree radial growth in Dagang Mountain area was significantly affected by the precipitation during the growing season from July to September, which showed a negative correlation.On the basis of response analysis, we have reconstructed the precipitation data which was proved to be reliable by the cross validation in July-September of every year since 1892 in Dagang Mountain area for the first time. The reconstructing results showed that the precipitation changes of July-September in past 117 years had been experienced generally 3 partial dry periods and 3 partial wet periods in Dagang Mountain area: 1895-1902, 1908-1926 and 1944-1985; 1903-1907, 1927-1943 and 1986-2008. In addition, the apparent mutation variance of the reconstructing precipitation sequence in 1921, 1977 and 1937, shows that there is a phase change existing in the precipitation change trend in the region for hundreds of years.