1. College of Life Science and Technology; Heilongjiang Bayi Agricultural University; Daqing P. R. China
2. Department of Plant Biology & Ecology, College of Life Science; Nankai University; Tianjin P. R. China
3. Silviculture and Forest Ecological Studies; Hokkaido University; Sapporo Japan
4. Research Center for Eco-Environmental Sciences of Yellow River Delta; Binzhou University; Binzhou P. R. China