The Kasuya Research Forest (KRF) is located in the northern part of Kyushu Island. The elevation ranges from 30 to 553m. About 100ha of there forests is on hilly Tertiary mountains lower than 100m in altitude, and other forests are on the steep mountains over the Paleozoic strata. Most of the natural forests consist of warm temperate evergreen broad-leaved trees such as Quercus sp., Castanopsis sp., Machilus thunbergii, Morella rubra, etc. The drier ridge sites are covered by deciduous broad-leaved trees such as Carpinus tschonoskii, Quercus serrata, Castanea crenata, etc. Plantation forests composed predominantly of Cryptomeria japonica and Chamaecyparis obtusa cover about 70% of the total forest area.