Study On Contents And Spatial Distribution Characteristics Of Soil Carbon,Nitrogen And Phosphorus In Bailong River Basin

Bailong River Basin is located in staggered area of Longnan mountain area,Qinling-Daba Mountain area,and Sichuan Basin area,surrounded by the three highly sensitive areas,making the Bailong River Basin was the most famous erosion and geological disasters-prone areas,at the same time,it is the most important ecological function protection area of upper reaches of the Yangtze River.The change of land use type by human activities has further exacerbated the deterioration of soil and water and the ecological environment,and it is urgent to carry out large-scale ecological restoration in that area.As an important component of ecosystem,soil’s carbon(C)element,nitrogen(N)element and phosphorus element(P)content and their ecological chemical metrological characteristics is an important basis for effectively measuring soil quality and ecological restoration.It making great significance for soil ecological restoration and the mechanism of Earth biochemical cycle to understand the three elements cycle and balance mechanism.In this study,the C,N,P content and distribution characteristics of soil vertical profile under different land use in Bailong River Basin were systematically investigated,and the relationship between C,N and P elements was quantitatively analyzed by eco-chemical metrology.Similarly,the spatial characteristics of these three elements are also analyzed,conclusion as followed :(1)Soil carbon and nitrogen content in forest are rich,soil stoichiometric ratio is stable status.Soil organic carbon content and soil total nitrogen content are gradually decreased with the soil profile,which have obvious surface accumulation phenomenon.Compared with other land use types,soil organic carbon content and total nitrogen levels of forest reach the first class level on average,and C:N,C:P and N:P achieve the national average level according to the second national soil census,the characteristics of stoichiometric ratio are stable.(2)Soil organic carbon content is the main factor affecting soil quality.SOC was the main factor affecting soil C:N,C:P,N:P,and soil TP had no significant effect on soil stoichiometricratio.(3)In Bailong River Basin,the contents and the soil stoichiometric ratio levels of soil carbon,nitrogen and phosphorus are low.Soil organic carbon,total nitrogen and total phosphorus upper second area accounting for 40.28%,39.97% and 50.47% respectively.Soil C:N,C:P and N:P are far lower than the global average,but achieve the national average area accounting for 14.98%,1.95% and 47.54% respectively.(4)The spatial distribution of soil stoichiometric ratio characteristics is significantly different across the Bailong River Basin.C:N ratio in a unbalance status in the middle reaches.The studies show that there is lacking of C element in the right shore side while lacking N elements in the left shore side.Human activities is the main factor of the phenomenon.