Abstract: Using an incubation experiment, we examined the effects of nitrogen (N) addition and warming on litter decomposition and carbon (C), nitrogen (N), and phosphorus (P) stoichiometric characteristics of Chinese fir (Cunninghamia lanceolata) leaves with different ages. We collected litter from a longterm N addition \[CK (0), N1 (50 kg N·hm^-2·a^-1), N2 (100 kg N·hm^-2·a^-1)\] experiment in subtropical Chinese fir plantation, Qianyanzhou, Jiangxi, China. Litters from one and two-year-old leaves of Chinese fir were used for incubation under two temperatures (20 and 30 ℃). The results showed that N addition did not affect C concentrations of decomposing Chinese fir litter, while significantly increased N concentrations and decreased P concentrations. Both N and P concentrations of decomposing litter were higher in one-year-old leaf than that in two-year-old leaf. In the early decomposition stage, litter P concentrations was higher with N2 than that with N1 or CK. Nitrogen addition significantly reduced litter C∶N ratio and increased litter C∶P and N∶P ratios. During decomposition, litter C∶N and C∶P ratios under the same N addition level were higher in two-year-old leaf than that in oneyearold leaf, while N∶P ratio showed the opposite trend. Litter C∶N and C∶P ratios were significantly increased with warming during litter decomposition. Under the same temperature, C∶N ratio was higher in one-year-old leaf than that in two-year-old leaf. Litter N∶P ratio increased with incubation temperature and was higher in one-year-old leaf than two-year-old leaf. Our results suggested that the effects of litter decomposition with different leaf ages, N input, and temperature on soil C and N cycling should be considered in the management of Chinese fir forests.

Key words: ecological stoichiometry, leaf age, Cunninghamia lanceolata, nutrient turnover.