1. Key Lab. of Wetland Ecology and Environment; Northeast Institute of Geography and Agroecology Chinese Academy of Sciences; 3195 Weishan Road Gaoxin District Changchun Jilin 130012 China
2. Eastern Cereal and Oilseed Research Centre Research Branch; Agriculture and Agri-Food Canada; K.W. Neatby Building 960 Carling Ave. Ottawa ON K1A 0C6 Canada