Study On Soil Carbon, Nitrogen And Phosphorus And Ecological Stoichiometry Characteristics Of Baotou Yellow River Wetland

Soil is the most basic component of wetland ecosystem,providing various organisms with nutrients required for their growth and development,among which carbon,nitrogen and phosphorus are the key nutrients and the key to the elemental cycle of the ecosystem.Therefore,the investigation of soil carbon,nitrogen,phosphorus and their ecological stoichiometry characteristics is an important indicator of soil quality and ecological quality.As an important ecological function area in Baotou,studying the distribution of soil carbon,nitrogen,phosphorus and their ecological stoichiometry characteristics can provide scientific basic data for the ecological construction and restoration of Baotou Yellow River Wetland Reserve,and has practical significance for the land use in Baotou.In this study,the soil of Baotou Yellow River Wetland was used as the research object.After the field survey,seven soil sample sites were identified from west to east to investigate the distribution of organic carbon,total nitrogen,total phosphorus and ecological chemometric characteristics of Baotou Yellow River;and different wetland types(completely natural,disturbed natural and degraded natural)were selected to investigate their soil organic carbon,total nitrogen,total phosphorus and ecological chemometric characteristics,and the results are as follows:(1)The mean values of soil organic carbon content,total nitrogen content and total phosphorus content in Baotou Yellow River wetland were 7.66 g/kg,0.41 g/kg and 0.87g/kg,respectively.The vertical distribution of soil organic carbon and soil total nitrogen content was characterized by decreasing with increasing soil depth,and no significant change in soil total phosphorus content with increasing soil depth.Soil organic carbon content,total nitrogen content and total phosphorus content increased significantly in the surface soil in 2021,which is due to the significant decrease of human intrusion activities,and there is no obvious pattern of their changes with time.(2)The mean values of soil organic carbon,total nitrogen and total phosphorus reserves in Baotou Yellow River Wetland are 6.42 kg/m2,0.34 kg/m2 and 0.74 kg/m2,respectively,and the vertical changes of soil organic carbon and total nitrogen reserves are characterized by decreasing with increasing soil depth,and the reserves in the surface layer(0-20 cm)account for nearly 50% of all reserves.No significant change with the increase of soil depth.(3)The mean values of soil C/N,C/P and N/P are 20.70,7.73 and 0.39,respectively.The soil C/N value is higher than the average value of the national swamp wetland,and there is no significant change with the increase of soil depth;the soil C/P value and soil N/P value are smaller than the average value of the national swamp wetland,and they all show a decreasing trend with the increase of soil depth.It shows that soil nitrogen is the limiting element in the Yellow River wetland.(4)Soil organic carbon content,total nitrogen content and total phosphorus content in Baotou Yellow River wetland showed highly significant positive correlation with each other(p < 0.01),and soil capacitance showed highly significant negative correlation with soil organic carbon content,soil total nitrogen content and soil total phosphorus content(p < 0.01).Soil p H was significantly negatively correlated(p < 0.05)with soil organic carbon content and soil total nitrogen content,and negatively correlated with soil total phosphorus content.Soil water content was highly significantly positively correlated with soil organic carbon content,soil total nitrogen content,and soil total phosphorus content(p < 0.01).At the same time,we got that soil organic carbon content,soil total nitrogen content,soil total phosphorus content and soil N/P were more related to soil water content and soil bulk weight by typical correlation.(5)The mean values of soil organic carbon content in different wetland types were:complete natural wetland(5.87-24.67 g/kg)> disturbed natural wetland(4.76-5.39g/kg)> degraded natural wetland(3.08-3.86 g/kg);soil total nitrogen content was:complete natural wetland(0.34-1.39 g/kg)> disturbed natural(0.22-0.27 g/kg)>degraded natural wetland(0.13-0.14 g/kg);soil total phosphorus content was;complete natural wetland(0.74-2.33 g/kg)> disturbed natural wetland(0.59-0.65 g/kg)> degraded natural wetland(0.49-0.56 g/kg).It indicates that the anthropogenic intrusive activities have damaged the soil environment of the wetlands and led to the loss of nutrients.The vertical distribution characteristics of soil organic carbon content and total nitrogen content of different wetland types are the same,all decreasing with the increase of soil depth,and soil total phosphorus content does not change significantly with the increase of soil depth;its change with time has no obvious pattern,and it increases significantly in 2021,which is due to the significant decrease of human intrusion activities.(6)The mean values of soil C/N of different wetland types showed that degraded natural type wetland(24.05)> disturbed natural type wetland(20.49)> completely natural type wetland(17.63),and their soil C/N did not change significantly in the vertical direction.The mean values of soil C/P in wetlands showed that fully natural wetlands(4.24)> disturbed natural wetlands(3.02)> degraded natural wetlands(2.48),which decreased in the vertical direction with increasing soil depth.The mean values of soil N/P in wetlands showed complete natural type wetlands(0.50)> disturbed natural type wetlands(0.37)> degraded natural type wetlands(0.25).It was consistent with soil C/P in the vertical direction.