1. School of Environment and Institute of Grassland Science, and Key Laboratory of Vegetation Ecology and Key Laboratory for Wetland Ecology and Vegetation Restoration Northeast Normal University Changchun Jilin 130024 China
2. Department of Ecology and Evolutionary Biology Institute of Arctic and Alpine Research University of Colorado at Boulder Boulder Colorado 80309 USA
3. Department of Ecology College of Life Sciences Inner Mongolia University Hohhot Inner Mongolia 010021 China
4. Institute of Mycology Jilin Agricultural University Changchun Jilin 130118 China