1. Institute of Fragile Eco-Environment, School of Geographic Science, Nantong University, 9 Seyuan Road, Nantong 226019, China
2. School of Agriculture and Environment, College of Science, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand
3. Forestry Station of Huangnan Prefecture of Qinghai Province, 14 Regong Road, Tongren 811300, China