Abstract: [Objective] In this research, we have studied the diameter structure, tree height structure, spatial distribution and soil physicochemical characteristics of young plantation of Picea asperata with different densities and investigated the optimum stand retention density of plantation in Southern Gansu, the purpose of these efforts were to provide scientific basis for the construction and sustainable management of Picea asperata plantation.[Method] In this study, 28 plots within 7 levels of tree densities (850, 1 060, 1 350, 1 550, 1 750, 2 300, 3 000 individual·hm^-2) in young plantation of Picea asperata were studied by method of sample plot investigation, uniform angle index and stratified sampling analysis, determined the diameter class structure, tree height structure, uniform angle index, soil density, saturated moisture, field capacity, capillary capacity, total prosity, capillary prosity, organic matter, total nitrogen, total phosphorus, total potassium, available nitrogen, available phosphorus and available potassium etc.,calculated the average value of each index, standard deviation, and the differences between the various indices.[Result] The growth of the average DBH and average crown width all decreased along with the increase of density, the average height increased at first then decreased with the increased of density. The diameter and height structure with different densities were unimodal curves belong to normal distribution, the peak diameter gradually decreases with the increase of density, the frequency of tree medium diameter (DBH:12-24 cm) were much more than diameter (DBH>24 cm) and (DBH<12 cm). Using spatial structure parameters of the uniform angle index to study the spatial structure characteristics of forest, the uniform angle index gradually decreases with the increase of density, the stand structure was random distribution when the stand density was less than 1 550 individual·hm^-2 and when the stand density was greater than 1 550 individual·hm^-2, it was uniform distribution. The stand density was the key factor affecting the soil physical and chemical properties (especially soil organic matter and total porosity) in young plantation of Picea asperata; In the plantations with moderate stand density(1 550 individual·hm^-2), soil nutrient contents were higher, but soil density was the lowest, the saturated moisture, capillary capacity, field capacity, and the total porosity were relatively higher in the soil depth of 0-20 cm, the soil physical and chemical properties were better than over crowded or over sparse forest.[Conclusion] Tree density was closely related to the stand structure, soil physical and chemical properties. An appropriate density(1 550 individual·hm^-2) could be helpful for maintaining good forest structure characteristics and soil physical and chemical properties, and was the best density of young plantation of Picea asperata in southern Gansu.

Key words: Picea asperata plantation, tree density, stand structure, soil property, diameter structure, height structure, spatial distribution pattern