1. Graduate Student, School of Ecological and Environmental Sciences, East China Normal Univ., 500# Dongchuan Rd., Shanghai 200241, China.
2. Professor, School of Ecological and Environmental Sciences, East China Normal Univ., 500# Dongchuan Rd., Shanghai 200241, China; and Shanghai Key Lab of Urban Ecological Processes and Eco-restoration, 500# Dongchuan Rd., Shanghai 200241, China (corresponding author).
3. Professor, Dept. of Geography, Univ. of North Carolina at Chapel Hill, CB# 3220, 205 Saunders Hall, Chapel Hill, NC 27599.