Key points are not available for this paper at this time.
Leaf litter decomposition mediates critical ecosystem nutrient cycling processes and plays a pivotal role in regulating nutrient dynamics processes in subtropical forests. Nevertheless, the mechanisms by which mixed plantation leaf litter quality regulates decomposition under nitrogen (N) deposition remain poorly understood, particularly in subtropical forests experiencing chronic high nitrogen deposition. Herein, we conducted a one-year field litterbag experiment in a mixed planation of Cunninghamia lanceolata and Phoebe bournei . Five levels of N addition: control (0 g N m 2 y −1 ), N1 (7 g N m 2 y −1 ), N2 (14 g N m 2 y −1 ), N3 (28 g N m 2 y −1 ), and N4 (56 g N m 2 y −1 ) were applied. N addition reduced the release rates of leaf litter carbon (C), N, phosphorus (P), and potassium (K). N addition accelerated cellulose degradation of P. bournei leaf litter during the early stage but inhibited it in the late stage, whereas cellulose degradation in C. lanceolata leaf litter was generally enhanced throughout the whole decomposition period. In contrast, lignin degradation was consistently inhibited by N addition during the decomposition process. The decomposition rate of two leaf litter was significantly reduced by N addition, with the strength of this effect being strongly dependent on the N addition rate. The control (CK) treatment exhibited higher decomposition rates compared to N addition. In addition, the decomposition rate of P. bournei leaf litter was faster than that of C. lanceolata leaf litter. The results were further revealed that N addition decreased decomposition rate indirectly by altering leaf litter stoichiometric ratios such as C: N, N: P, and lignin: N ratios. The research brings to light that the stoichiometric ratio of leaf litter should be considered a significant factor in regulating decomposition dynamics of leaf litter and nutrient cycling, particularly in the context of increasing N deposition intensification in subtropical forests.
Zhang et al. (Sun,) studied this question.