[Population dynamics of Quercus variabilis on northern slope of Qinling mountains]

Studies on the population dynamics, age structure, spatial distribution pattern, life table, and survival curve of Quercus variabilis showed that the Q. variabilis population on the northern slope of Qinling mountains was increasing. The number of young-aged individuals was larger, and that of middle-aged and old individuals was smaller. The life tables for different age classes showed that the mortality at age classes I and II was the highest, and the mortality rate was decreased with increasing age. However, at age classes VII and VIII, the mortality rose again for their decrepitude. The expected life span of age classes III, IV and V was higher, and decreased gradually with increasing age. The survival curves were the type of Deevey III, and the distribution pattern of population was aggregative as a whole. As the age increased, the intensity of aggregation decreased, and tended to a random distribution at higher elevations. A wise management should accelerate the recovery of Q. variabilis population and the enhancement of its productivity. The altitude 800-1,100 m was the favorable habitat for Q. variabilis population. As for the Q. variabilis at lower altitude, its protection should be reinforced, and the disturbance from human beings should be reduced. Forest thinning and other fostering management at middle altitude should be given in time. The target trees at higher altitude should be fostered.