1. Kyushu University Forest, Kyushu University, Sasaguri, Fukuoka 811-2415, Japan
2. Graduate School of Bioresource and Bioenvironmental Science, Kyushu University, Fukuoka, Japan
3. Ashoro Research Forest, Kyushu University, Hokkaido, Japan
4. Department of Plant Sciences, Graduate School of Agricultural Science, Kobe University, Kobe, Japan