Abstract:

The biomass structure and soil fertility in 29 years old Chinese fir stands of 5 different densities were studied. The results show that the biomass of mean individual and its each organ tend to decrease with the increasing of density; The biomass and the productivity per unit area tend to consistant; The amount of litter per unit area increases with the increasing of density, but the development of the ground vegetation and its biomass are at the contrary. The soil moisture content, maximum water-holding, and capillary water-holding capacities of stands with 2805 and 3750 trees per hectare are greater than others, the soil porosity increases with the increasing of density, and the content of soil organic substances, total nitrogen (N), total phosphorous (P), available nitrogen and available phosphorous are decreasing with the incerasing of density, but the tendency of available potassium content is not evident. The planting density of Chinese fir must be confined from 2805 to 3750 trees per hectare in order to raise the yield and maintain the soil fertility.

Key words: Chinese fir, Planting density, Biomass structure, Soil fertility