Responses of vegetation and soil ecological stoichiometry to precipitation in desert steppe

Changes in precipitation have an important impact on the element cycle between plants and soil, especially in arid areas. Therefore, to better understand the impact of different precipitation gradients on the stoichiometric characteristics of the desert grassland ecosystem, we considered the desert grassland of Yanchi County in Ningxia as the research object, used rain shelters to manually adjust the rainfall in the study area, and measured the carbon (C), nitrogen (N), and phosphorus (P) contents of the plant community and soil of five different precipitation gradients 33%, 66%, 100% (Control), 133%, and 166%. We analyzed the ecological stoichiometric characteristics of the plant community and soil. The results showed that 1) the C content gradually decreases with an increase in the precipitation gradients. The content of N ꞉ P of normal rainfall is significantly higher (P < 0.05) than the rainfall enhancement treatment in above-ground parts of the plant community, the contents of C, N, and P first decrease then increase with the increase of rainfall gradient in below-ground parts of the plant community, and the contents of C, C ꞉ N, and C ꞉ P are significantly higher than the treatment of increasing rainfall under the 66% rain reduction treatment (P < 0.05). 2) Soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) increase with the increase of rainfall. The SOC, TN, and TP of the surface soil are significantly higher than those of the deep soil layer (P < 0.05) in the treatment of increasing rainfall. 3) There was a significant negative correlation between soil SOC and P contents in the above-ground part of the plant community (P < 0.05) but no significant correlation between soil C, N, and P contents in other parts of the plant community.Precipitation changes can change plant nutrient allocation and increase soil nutrient accumulation, but the coupling relationship between plant and soil elements in desert steppe is weak.