| The Tumen River downstream is one of the key wetlands in Jilin Province,which located at the junction of China,Korea and Russia.Artificial fertilization leads to the increase of soil nutrients,which affects the composition of wetland plant communities and threatens the health of Wetland.In this paper,the agriculture/wetland ecotone in the Tumen river downstream is taken to study the effect of agricultural activities on plant nitrogen and phosphorus.The paddy field soil,natural wetland soil(with or without water)?transition zone(with or without water)were selected and we take the Glyceria spiculosa as example to study the relationship of nitrogen and phosphorus between the plant organs(root,root,stem and leaf)and environment.(1)The average content of total nitrogen(TN),total phosphorus(TP),available nitrogen(AN)and available phosphorus(AP)in the transition zone1 was significantly higher than that in paddy field and natural wetland.TN,AN and AP in transion2 were less than that in agriculture and natural wetland,but the TP is more than that in paddy field and natural wetland.The TN and TP in natural wetland were higher than that in paddy field,AN and AP were less than that in paddy field.The average ratio of N:P in soil was as follows,natural wetland(1.32)>transition 1(1.02)>paddy field(0.71)>transition 2(0.24).The average content of TN,TP,AN and AP in soil showed:the natural wetland1>natural wetland2,N:P showed that natural wetland2>natural wetland 1.The TN,AN and N:P in the transition zone1 showed that increasing and then decreasing with the increase distance of farmland.The contents of TN,AN,TP,AP,and N:P in the soil of paddy ditches zone have certain differences.(2)The main root,fine root,stem and leaves of the Glyceria spiculosa had the higest content of TN and TP in transion zone1,followed by the natural wetland and the transition zone2.The ratio of N:P the stem and leaf of the Glyceria spiculosa in the transition zone1,the the main root in nature wetland and the fine root in transition zone2 were the largest.According to the different water depth in nature wetland,the content of TN,TP and N:P of the main root,fine root,stem and leaf in Glyceria spiculosa showed:natural wetland1>natural wetland2,TP of main root and N:P of fine root in plant take the contrast trend.Two-way ANOVA showed water is the main factor that influence the nitrogen and phosphorus of the plant,land use and water influence the nitrogen of the fine root.(3)Comprehensive analysis the homeostasis of nitrogen(HN),phosphorus(HP)and nitrogen phosphorus ratio(HN:P)in plant organs,leave HP(2.78)>HN(1.75),root HP(2.22)>HN(1.47),fine root HN:P(2.38)>HP(1.52)>HN(1.45),stem HN:P(2.08)>HP(1.79)>HN(1.69),The ecological stoichiometry homeostasis of main root,fine root,stem and leave in plant were small,the results showed that the plant was nitrogen limited and easily affected by nitrogen.Nitrogen content increased in transition zone 1 influenced by paddy field and effects on the growth of Glyceria spiculosa.Through the correlation analysis of nitrogen and phosphorus in soil and water environment with plant nitrogen and phosphorus,the nitrogen and phosphorus in plant were significantly correlated with soil AN and AP(p<0.05).but the plant nitrogen and phosphorus in the transitional zone were significantly correlated with soil AN and AP,some organs were significantly correlated with total nitrogen and total phosphorus in soil(p<0.05).The results showed that plant growth environment in transition zone had changed the utilize ways of nitrogen and phosphorus response process affected by paddy field.In total,the cultivation of paddy field and water in this area has changed the distribution of nitrogen and phosphorus in the surrounding wetland and affected the balance of nitrogen and phosphorus in wetland plants.Long term,it may affect the structure of wetland plant communities and threaten the stability of wetland ecosystem structure and function.We should enhance the management of paddy field in order to protect the wetland. |
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