Study on Regularity of Radial Growth of Cunninghamia lanceolata Plantations After Climate Change

Dendrochronology method was applied to compare the difference in the average growth rate of Cunninghamia lanceolata in different sample plots in varied years by taking the mature C. lanceolata plantation on Jiangle Forest Farm, Fujian Province established in 1982 as study object. The regularity of the radial growth of C. lanceolata was studied by classifying the radial growth stage of the individual plant, and by identifying the growth release process. The results showed that the average growth rates during 1992-1996 in five plots were all significantly higher than those of other time periods (p<0.05), while the average growth rate of JL3 plot in that time duration was much lower than that of the other sample plots (p<0.05). The growth course of C. lanceolata could be divided into three stages, i.e., the rapid growth stage(1-6 a), slow growth stage(7-15 a) and stable growth period (16 a above). The average annual radial growth rate of C. lanceolata was 8.38 mm/a, which reached the peak value at 6 a and matured at 22 a. There was a tendency that the annual growth rate increased gradually. There were mutational growth within the rapid growth period (around 1986, in the year of 1994 and 2005). An over 35% of mediumlevel growth release took place between 1984-1986, which might be caused by the formation of forest gaps. However, the growth releases happened in 1994 and 2005 were related to the increase of precipitation in these years.