Abstract: Litter decomposition is an important process of energy flow and nutrient cycling in forests. Leaf litter includes naturally senescent leaf litter (SL) and green leaf litter (GL). It is not clear whether the responses of litter decomposition and nutrient releases between SL and GL to thinning intensity and fertilization in plantations are different. In this study, we compared the effects of thinning intensity and fertilization management on the decomposition rate and nutrient releases of C, N and P in the naturally senescent and green leaf litter in a 13-year-old Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) plantation. Our results showed that the dynamics of decomposition and nutrient release were similar between SL and GL. The decomposition rate and litter C, N and P releases were significantly faster in GL than SL. The remaining rates of dry matter in SL and GL were 58.4% and 40.5% after 1-year decomposition, respectively. Thinning intensity did not affect decomposition rate and the remaining rates of litter C, N, and P. Fertilization decreased dry matter remaining rate under medium thinning, but increased leaf litter N and P concentrations and the remaining rate of P content. Our results implied that litter chemical properties was one of the most important factors controlling litter decomposition rate and nutrient releases, and highlighted that reserving green leaf litter derived from thinning management was necessary to maintaining soil nutrient in Chinese fir plantations.

Key words: leaf litter, Chinese fir plantation, thinning intensity, fertilization, nutrient release, decomposition rate.