Stand structure and its relationship with environmental factors of Picea crassifolia in Qilian mountains

【Objective】In order to provide scientific basis for scientific management, sustainable utilization of Picea crassifolia, and ecosystem stabilization and restoration in Qilian mountains, we explored the relationship between stand structure and environmental factors, and found out the main factors affecting the stand structure of Picea crassifolia.【Method】Picea crassifolia which distributed in Pailugou catchment of Qilian mountains was selected as objects, and investigated the characteristics of vegetation structure and site factors of 15 fixed sample plots(20 m×20 m), the distribution characteristics of stand structure and site factors of Picea crassifolia were studied by using descriptive statistics method, and the relationship between stand structure and site factors was analyzed by redundancy analysis method.【Result】The diameter structure, tree height structure, crown length structure and crown width structure were all distributed to the left, the relationship between diameter, height, crown length, crown width and abundance was cubic polynomial, the abundance of diameter level from 1-5 cm to 21-25 cm, height from 2-4 m to 14-16 m, crown length from 1-2 m to 8-10 m, and crown width from 2-4 m to 4-6 m was 93.10%、91.56%、80.23% and 83.4 xx le 2% respectively. Altitude and slope had great correlation with diameter, crown length and crown width, slope aspect had little correlation with diameter, crown width, crown length and stand age, the temperature of 20-40 cm soil layer had great correlation with tree height, the temperature of 0-10 cm soil layer had great correlation with crown density, soil volume water content was positively correlated with diameter, crown length and crown width, but negatively correlated with tree height and canopy density, the water content of 40-60 cm soil layer well explained the variation of stand structure.【Conclusion】The water content of 40-60 cm soil layer was the main factor which affects the stand structure of Picea crassifolia in Pailugou watershed of Qilian mountains.