2015 Volume 24 Issue 2 Pages 1-9
Ten years after group cutting to promote regeneration of broad-leaved tree species, we investigated litterfall and the organic horizon (O-horizon) at three different slope positions in a secondary hinoki cypress-dominated forest. The aim was to determine the effects of the cutting on nitrogen (N) cycling. In the cut plots on the middle and lower slopes, where abundant tall broad-leaved tree species had regenerated, carbon (C) and N inputs by leaflitter from these trees were higher, and the litterfall C/N ratio was lower, than in the control plots. In contrast, on the upper slope, where abundant woody shrubs had regenerated, these parameters did not differ between the control and cut plots. Litterfall C/N ratio decreased with increasing N input by leaf litter from broad-leaved species. Stocks and mean residence times (MRTs) of C and N in the O-horizon were lower in the cut plots than in control plots at the same positions. The MRTs of C and N in the O-horizon decreased as the litterfall C/N ratio decreased. The decrease in MRTs in the O-horizon in the cut plots was much greater at the middle and lower slope positions than at the upper position. These results suggest that the change in MRTs in the O-horizon at each position 10 years after group cutting is strongly influenced by the type of tree species that regenerates in the cut plots, but not by differences in soil nutrition along the slope.
