Key Laboratory of Wetland Ecology and Environment,Northeast Institute of Geography and Agroecology,Chinese Academy of Sciences,Changchun 130102,China

College of Resources and Environment,University of Chinese Academy of Sciences,Beijing 100049,China

State Key Laboratory of Black Soils Conservation and Utilization,Changchun 130102,China

Department of Natural Sciences,Middlesex University,Hendon,London,NW4 4BT,UK

Xingkaihu Branch Office of Heilongjiang Agriculture Co.,LTD,Jixi 158325,China