1. College of Biology and the Environment, Nanjing Forestry University, Longpan Road 159, Xuanwu District, Nanjing 210037, China
2. Section of Ecology and Biodiversity, Institute of Environmental Biology, Utrecht University, Padualaan 8, 3584CH Utrecht, The Netherlands
3. Centre for Crop Systems Analysis, Wageningen University, P.O. Box 430, 6700AK Wageningen, The Netherlands