Characteristics And Influencing Factors Of Ecological Stoichiometry In Natural Wetland And Paddy

Wetland is the overlapped areas of the global waters and land areas.It accounts for 5% of global land area and can be divided into natural and constructed wetlands according to their formations.Ecological stoichiometry is an important scientific sense and guidance for the protection and restoration of wetland ecosystems.However,the ecological stoichiometry of natural wetlands or constructed wetlands was usually researched seperately,and were rarely studied together.In this study,the ecological stoichiometry of carbon(C),nitrogen(N),phosphorus(P),and sulfur(S)in plant,sediment and soil for both natural and artificial wetlands and its response to fertilizer and water level were studied comparatively.The results showed that:(1)The N:P value of plant leaves(Nelumbo SP)and plants(other plants)in Baiyangdian wetland was lower than 14,which preliminarily indicates that Baiyangdian wetland is N-limited.The C: N,C: P values of Baiyangdian plant leaves were lower than those of other plants such as Great Hing’an Mountains peatlands,global plants,Chinese forests and grasslands,indicating that the utilization efficiency of N and P in Baiyangdian wetland is low.The correlation analysis of C,N,P and S elements in Baiyangdian sediments showed that the correlation between C,N and S elements was significant.We infered that elements C,N and S are mainly derived from plant litter and organic matter.(2)In the positioning experiments,the soil elements were generally more sensitive to fertilization than that of straw and water level.The application of organic fertilizer was conducive to the accumulation of soil C,N and S content.In contrast,long-term application of chemical fertilizers was conducive to the accumulation of C,N and P in straw.After the subsequent fertilization changes,the changes in soil and straw element content depended more on subsequent fertilization.There was an interaction between fertilization and water level.Under different fertilization types,the soil and straw element contents and their metering ratios responded to water levels differently.At the same time,under different water level controls,the soil and straw element contents and their metering ratios responded differently to fertilization.(3)In the pot experiment with sulfur fertilizer application,the variations of C content in rice straw and roots under different treatments were small,while the variations of S content in rice roots and soil were large.The P: S values of rice straw,roots and soils had a large degree of variation,while C: N values had a relatively small degree of variation.The results suggest that P and S are in a decoupled state,and C and N are strongly coupled.Furthermore,the application of S fertilizer caused the C: N,C: P,N:P values of the straw to increase,which indicates that the application of sulfur fertilizer affects the stoichiometry of the element by increasing the carbon assimilation capacity of rice and changing the element content of rice plants.(4)The spatial variability of C content in natural wetland plants and rice straw was significantly smaller than that of N,P,and S.The variation coefficient of P content was the largest.The range of ecological stoichiometry of rice straw C,N and P was larger than that of wetland plants(except C: N).The results indicate that wetland plants and rice have good ecological adaptability to the bioavailability of phosphorus in the environment,and rice is more adaptable to nutritional imbalances than other wetland plants.