Dynamic characteristics of litter decomposition and nutrient release of three common emergent plants

The decomposition of wetland plant litter is important for maintaining the structural and functional stability of wetland ecosystems. Here, to explore the dynamics of litter decomposition and nutrient release in wetland plants, we selected three common emergent aquatic plants, i.e., Phragmites australis, Triarrhena lutarioriparia, and Zizania latifolia. We investigated their decomposition rates, contents and stoichiometric ratios of carbon, nitrogen, and phosphorus, and the process of decomposition of single and mixed species. Results showed that whether single or mixed species, the most rapid litter decomposition occurred in the first 5 d. Subsequently, the decomposition rate decreased sharply, then slowly decreased until stable. The decomposition rate was correlated with initial nitrogen and phosphorus content of the litter, and nutrient return was significantly positively correlated with the instantaneous decomposition rate constant. Mixed decomposition may be influenced by nutrient migration and decomposition, showing synergistic effects in the early and end decomposition stages, and antagonistic effects in the middle decomposition stages. Our research indicated that mixed litter decomposition was not the additive effect of single litter decomposition, and further study of the mechanisms of litter decomposition is needed.