In a series of the investigations on orgainc matter decomposition at Sambe Forest of Shimane University, decomposition rates for various forest litters were calculated from the measurements of the amounts of litter fall and organic matter in A_0 horizon. The results of these calculations were well in accordance with the well-known general tendencies of organic matter decomposition along the slope of mountain in the warm temperate forest of Japan.
To clarify some factors affecting these phenomena of litter decomposition, the fallen leaves of seven species of deciduous broad-leaved trees were compared in their decomposition rates by litter bag method. After 229days breakdown, the weight loss of each species was as follows : Cornus Kousa 85%, a mixture of Cornus controversa and C. macrophylla 60%, a mixture of Carapinus Tschonoskii and C. laxiflora 51%, Castanea crenata 49%, Prunus Sargentii 47%, Styrax Obassia 43%, and Quercus serrata 38%. No apparent differences in weight loss occurred among the places along the slope.