1. College of Life Science, Northwest Normal University, Lanzhou, Gansu 730070, China; 2. Management Bureau of Liancheng National Nature Reserve, Yongdeng, Gansu 730333, China; 3. Key Laboratory of Arid and Grassland Ecology of the Ministry of Education, Lanzhou University, Lanzhou, Gansu 730000, China
Using Hegyi's competition index model for individual tree,we analyzed the intraspecific and interspecific competition of Picea wilsonii in Liancheng National Nature Reserve of Gansu.The results showed that intraspecific competition intensity of Picea wilsonii reduced with the increase in diameter scale of the trees.The intraspecific competition was much larger than interspecific competition.The order of competition intensity(CI.) was listed as:Picea wilsonii>Populus davidiana>Acer tetramerum var.betulifolium>Pinus tabulaeformis>Salix sp.>Betula albo-sinensis.The relationship between competition intensity and individual growth of objective tree followed closely the following equation CI.= AD–B.When the diameter scale reached to 40 cm,there was little change of competition intensity.The CI.of Picea wilsonii was positively correlated with altitude.
