College of Resources and Environment Northeast Agricultural University Harbin 150030 P.R.China;
College of Surveying and Mapping Engineering Heilongjiang Institute of Technology Harbin 150050 P.R.China;
Land Management Institute Northeastern University Shenyang 110169 P.R.China;
College of Resources and Environment Northeast Agricultural University Harbin 150030 P.R.China;
Institute of Plant Nutrition and Resources Beijing Academy of Agricultural and Forestry Sciences Beijing 100097 P.R.China;
College of Resources and Environment Northeast Agricultural University Harbin 150030 P.R.China;
Land Management Institute Northeastern University Shenyang 110169 P.R.China;
