Abstract: Litter is the main source of soil organic matter, and its decomposition can be affected by various factors. As an important measure for high-yield management of bamboo forests, fertilization affects the formation of organic matter and nutrient cycling. To investigate the impacts of different nitrogen fertilization levels on the early processes of Phyllostachys edulis litter decomposition under the conditions of mixed applications of nitrogen (N), phosphorus (P), and potassium (K) fertilizers, an experiment was conducted with a fixed P and K application level and four N application levels: no N application (CK), low N (242 kg·hm^-2, LN), medium N (484 kg·hm^-2, MN), and high N (726 kg·hm^-2, HN). The effects of fertilization on mass loss, nutrient return, and stoichiometric ratio of litter during decomposition were examined. The results showed that after 13 months of decomposition, the rate of litter mass remaining was 67.5%-70.8% across various nitrogen application levels, which was not affected by fertilization. There were no significant differences in carbon content of decomposing litter among different treatments. Fertilization significantly promoted the enrichment of N and P in litter, which was 39.97%-45.76% and 64.25%-75.70% higher than that in the CK, respectively. Hemicellulose and cellulose contents decreased to different extents, with hemicellulose decomposing faster. The reduction of hemicellulose content was in an order of MN (50.13%) > LN (49.25%) > HN (42.44%) > CK (39.00%), while the reduction of cellulose content was LN (36.86%) > MN (31.98%) > HN (26.89%) > CK (24.41%). The LN and MN treatments significantly promoted the decomposition of total cellulose, while different treatments had no significant effect on lignin. In conclusion, different N fertilization levels did not affect litter mass loss at the early stage of decomposition, regulated nutrient release and the decomposition of carbon components, and significantly enhanced N and P enrichment of litter. LN and MN treatments effectively promoted the decomposition of total cellulose. All treatments did not affect the lignin and total carbon contents of litter.

Key words: litter decomposition, Phyllostachys eduli,  fertilization, nutrient return