Abstract
A 35-yr old Cryptomeria japonica plantation in Nuandai circle, which was thinned in 2007, will be selected to monitor its litterfall, litter layer, and litter decomposition for two years in order to study the influences of thinning on litterfall, litter layer, and litter decomposition at the stand. This is the second-year report. Having collected nine months litterfall in 2009, the preliminary results were the largest total mean annual litterfall at control stands (2.54 Mg ha-1 yr-1), the second at 25%-thinning stands (1.61 Mg ha-1 yr-1), and the smallest at 50%-thinning stands (1.45 Mg ha-1 yr-1). The litterfall amount differed widely among seasons. The largest amount occurred in September. The total amounts of litter layer during the first two season collections were 9.15, 17.45, and 12.42 Mg ha-1 at control, 25%-thinning, and 50% thinning stand, respectively. For those amounts there were no significant differences among treatments. The litter bags were collected after 12 and 18 months in the field. The mass remaining of needles and twigs ranged from 47.4 to 50.2% after 18-months decomposition. Since there were no significantly different among treatments, thinning had slightly influences on needles and twigs decomposition. After chemical analyses the means nutrient concentrations of litterfall (mean±standard deviation) were as follows: C: 539±4 mg g-1, N: 17.1±0.4 mg g-1, P: 1.07±0.03 mg g-1, K: 1.92±0.14 mg g-1, Ca: 15.6±0.8 mg g-1 and Mg: 2.41±0.17 mg g-1.