1. Department of Biology, Faculty of Science, Shinshu University , Asahi 3-1-1, Matsumoto, Nagano 390-8621 , Japan
2. Sugadaira Research Station, Mountain Science Center, University of Tsukuba , Sugadairakogen 1278-294, Ueda, Nagano 386-2204 , Japan
3. Division of Environmental Science and Ecological Engineering, College of Life Sciences, Korea University , Seoul 02841 , Republic of Korea
4. Institute of Mountain Science, Shinshu University , Asahi 3-1-1, Matsumoto, Nagano 390-8621 , Japan