Comparative Study on Underground Vegetation Develop of Different Generation Plantations of Chinese Fir

The underground vegetation of different generation plantations of Chinese fir (Cunninghamia lanceolata) are studied through the investigation of different generation, age and site. The results are as follows: underground vegetation development of Chinese fir plantations are greatly influenced by planting generation. There are significant differences among the underground vegetation species, frequencies and biomass of different generation plantations. Species quantities of the first generation, the second generation and the third generation plantations are 69, 54 and 59 respectively. There is not special species of different generation plantations. As planting generation increases, biomass and nutrient accumulations of underground vegetation of different generation plantations increase. Underground vegetation concentrations are higher than those of its litter. Compared to the first generation plantation, the nutrient accumulations of underground vegetation of the second generation, the third generation plantations increase by 6.96% and 37.49% respectively. Underground vegetation of Chinese fir plantation has higher capacity to accumulate nutrients.