1. Ph.D. Student, College of Geographical Sciences, Fujian Normal Univ., Fuzhou 350007, China.
2. Professor, College of Geographical Sciences, Fujian Normal Univ., Fuzhou 350007, China (corresponding author).
3. Professor, Ontario Ministry of Environment and Climate Change, Dorset Environmental Science Centre, 1026 Bellwood Acres Rd., Dorset, ON, Canada P0A 1E0.