1. Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau & Inner Mongolia Key Laboratory of Grassland Ecology, School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, PR China
2. Department of Bioresource Science, Ibaraki University College of Agriculture, Ami-machi, Ibaraki 300-0393, Japan
3. United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, Fuchu-shi, Tokyo 183-8509, Japan
4. Present address: Institute for Plant Protection, National Agriculture and Food Research Organization (NARO), Tsukuba, Ibaraki 305-8605, Japan
5. Present address: Center for Conservation Science and Restoration Techniques, National Research Institute for Cultural Properties, Tokyo, Taito-ku, Tokyo 110-8713, Japan