The Decomposition Dynamics Of Litter In Nine Wetland Plants And Its Effects On Soil Nitrogen Removal Process

Wetland ecosystems have high nitrogen removal capabilities,it can reduce nitrogen pollution through denitrification,anaerobic ammonia oxidation,plant absorption and other ways.Wetland plants play an important role in wetland ecosystem,their decomposition will affect the physical and chemical properties of wetland soil,and the soil biological characteristics.What’s more,it effect the nitrogen removal process of wetland soil.To explore how the litter decomposition of wetland plants affects the process of soil nitrogen removal,we selected nine common wetland plants including submerged plants,emergent plants and hygrophytes.Through studying the decomposition rate and nutrient release dynamics of single and mixed decomposition,and the removal process of soil nitrogen during litter decomposition by simulation control experiment,we hope to explore the relationship between litter decomposition and soil nitrogen removal,The main results are as follows:(1)The initial decomposition rate of litter decomposition is significantly related to the initial element content of litter,the higher litter origional N and P contents,the faster litter decomposition rate.The decomposition rate of the litter reaches a maximum at 5th day,and then it’s drops down until stable.(2)Nutrient return of the litter was significantly correlated with the instantaneous decomposition rate,emergent plants show a slow trend of the nutrient return in the late decomposition period.The emergent plants’ C:N,N:P ratios are significantly lower than the values of submerged plants and hygrophytes in the late decomposition period,but in the early stage of decomposition,it‘s significantly higher than the value of submerged plants and hygrophytes.(3)Soil denitrification and anammonia oxidation rate are directly affected by soil TC,TN content,and indirectly by soil p H.The rate of soil nitrogen removal was significantly correlated with the soil ammonia nitrogen and nitrate nitrogen content.In the early stage of litter decomposition,the process of soil nitrogen removal is dominated by denitrification,and the late stage of decomposition is completed by denitrification and anammonia oxidation.(4)Soil potential denitrification and anammonia oxidation rates in single plants’ decomposition were faster than those in mixed plants’ decomposition.Soil potential denitrification and anammonia oxidation rates in soil added with litters were faster than those in soil without litters.Our study provides a data basis for deeply understanding the nitrogen removal function of wetland ecosystem,and provides scientific support for wetland restoration work.