Abstract
It is a well-known theory regarding forest soils on the hilly topography of Japan that the influence of soil-moisture conditions on the decomposition of leaflitter is greater than that of the chemical composition of the leaflitter. This investigation is a re-examination of this theory. The effect of the species composition of the leaflitter on the decomposition rate of the Ao horizon was examined along the slope where no apparent effect of the soil-moisture conditions had been observed. The species composition of the leaflitter evidently was different on the ridge and on middle and lower parts of the slope. Mixed leaflitter collected on the ridge decomposed most slowly, and that on the lower part of the slope decomposed most rapidly. These results agreed not only with the estimated rate of decomposition calculated from the values of each species examined and their mixture ratio, but also with the annual decomposition rate calculated from the amount of the Ao horizon and the litterfall. This investigation suggests that the influence of the species composition of the leaflitter on decomposition should not be underestimated along the slope where the moisture conditions of the soil intensively affects the decomposition of the Ao horizon.
