Effect of nitrogen and phosphorus addition on litter decomposition and nutrients release in a tropical forest

Aims Through the nutrient fertilization experiment, we aimed to understand how litter decomposition and nutrient release response to the elevated soil N and P availability. Methods A factorial fertilization experiment was conducted in a tropical forest in South China. Leaf litters of five species (Acacia auriculaeformis, Syzygium levinei,Carallia brachiate,Schefflera octophylla,Aphanamixis polystachya) and their mixed sample were put into litter bags in plots fertilized with N, P, or N and P together and collected every three months during the 18-months decomposition. Mass loss of leaf litters and nutrients content were measured. Results N addition decreased decomposition rates by 15-40%, and the magnitude was species-specific, while P addition had no significant influence on the litter decomposition of all species. Decomposition rate of leaf litter were lower in species with higher C/P ratios and cellulose content. All types of litters served as a net N source during the decomposition. The amounts of mineral elements released during the decomposition followed the order: K > Mg > Ca, and N addition accelerated the Ca and Mg release from litters. Conclusions The result suggests that future high N deposition can reduce the tropical forest litter decomposition rate but enhance the mineral nutrients release, which may contribute to higher soil C sequestration, while soil P availability does not influence the litter decomposition.