1. College of Forestry, Sichuan Agricultural University, Chengdu, Sichuan Province, 611130, Sichuan, P.R. China
2. National Forestry and Grassland Administration Key Laboratory of Forest Resources Conservation and Ecological Safety on the Upper Reaches of the Yangtze River, College of Forestry, Sichuan Agricultural University, Chengdu, Sichuan Province, 611130, Sichuan, P.R. China