Characteristics and correlation analysis of stoichiometric ratio-enzyme activity in rhizosphere soil of Ulmus pumila in different regions of Inner Mongolia

In order to reveal the stoichiometric characteristics, enzyme activities and their interrelationships of soil nutrients in the root zone of Ulmus pumila L.natural sparse forests in different regions of central and eastern Inner Mongolia, nine typical Ulmus pumila natural sparse forest plots were selected in this study. The soil physical and chemical properties, C : N, C : P and N : P stoichiometric ratios, as well as sucrase, urease, acid phosphatase and alkaline phosphatase activities in 0-20 cm soil layer were measured, and the spatial differences and correlations were discussed by variance analysis, correlation analysis and principal component analysis. The results showed that the physical and chemical properties, stoichiometric ratio and enzyme activity of soil in different sites showed obvious spatial heterogeneity, and some of the sites had higher contents of organic matter, organic carbon, total nitrogen and available nutrients, reflecting that there were significant differences in the supply pattern of soil C, N and P resources under different site conditions. Soil C : N was significantly negatively correlated with sucrase and urease activities, and C : P was significantly correlated with phosphatase activity, and some enzyme activities showed synergistic changes, indicating that there was a certain coupling relationship between soil element balance and microbial potential resource acquisition input. Soil water content and some carbon and nitrogen nutrient indexes showed a certain synergistic change, indicating that water may be one of the important environmental factors affecting the accumulation and transformation of soil nutrients in the root zone of Ulmus pumila, but its role may also be regulated by soil type, pH, vegetation composition and other regional environmental factors. In general, there are obvious spatial differences in soil resource supply and enzymatic transformation processes in different Ulmus pumila natural sparse forests in central and eastern Inner Mongolia. The results can provide a scientific basis for understanding soil nutrient cycling and regional adaptation characteristics of Ulmus pumila natural sparse forests in arid and semi-arid regions.