Comparison and Study on the Productivity and Biomass Component Proportions of Different Rotation of Chinese Fir Plantations in Fenyi, Jiangxi Province

The productivity of first rotation of Chinese fir(Cunninghamia lanceolata) was compared with that of the second rotation. The tree height of dominant tree was used as the indicator, which was not influenced by the stand density but influenced by the site condition and age of the stand. The stand age on the first and the second generations sample plots of Chinese fir with similar site condition and development stage in Dagangshan of Jiangxi Province was in keeping with that of the main plot of first rotation, and height of dominant trees was calculated after the age changing by using Growth and Yield Model System of Chinese Fir Plantation, so as to compare the dominant heights between the first and second rotation stands with similar stand age and site conditions. Based on the data of practical measuring of biomass, the differences of biomass percentage of trunk, root and leaves were compared by the method of hypothesis testing. The results showed that there was no significant difference of productivity between the first and the second rotation young stands under various site conditions. The productivity of first rotation middle aged stand was higher than that of the second rotation stand. The poorer the site condition, the more significant the difference. For 4～12 years old stands, it was showed that:(1) The percentage of trunk in the total biomass was higher for first rotation stand than for the second rotation stand.(2) The percentage of root in the total biomass was lower for first rotation stand than for the second rotation stand. The poorer the site condition, the more significant the difference.(3) There existed no significant difference of percentage of leaves and branches in total biomass between first and second rotation stands.