Artificial grassland establishment alters soil metabolomes by reshaping multi-domain microbial networks

As a core component of power transmission, substations often receive little attention regarding their internal ecological conditions. In this study, we established artificial grasslands at the Xining 330 kV Huayuan Substation and evaluated their ecological benefits. Our results showed that Duchesnea indica (SP1) and Poa annua (SP4) exhibited extremely high coverage (>90%) and aboveground biomass, positioning them as ideal pioneer species for vegetation restoration. The establishment of artificial grasslands significantly increased soil available nutrient content and moisture, reduced soil pH, and created a more favorable microenvironment for microbial communities. Significant differences were observed in the β-diversity of soil bacteria, fungi, and protists: bacterial communities diverged only between the artificial grasslands and the control, whereas fungal and protist communities not only differed from the control but also showed significant separation among different grass species treatments. Atificial grasslands substantially enhanced the complexity of the multi-domain network encompassing bacteria, fungi, and protists; importantly, the degree centrality of the three groups did not differ, underscoring their equivalent importance in maintaining network structure. Untargeted LC-MS metabolomics identified a total of 877 soil metabolites, with lipids and lipid-like molecules being the predominant class. PLS-DA analysis revealed significant differences in metabolites among treatments, and random forest analysis identified protists and their associated micro-food webs as the primary factors driving variation in metabolite composition. In summary, the construction of artificial grasslands within substations triggered multidimensional and profound ecosystem changes, driving cascading effects that extended from aboveground plant communities through the soil micro-food web to soil metabolites. These findings provide a scientific basis for developing ecological restoration technologies based on targeted regulation of the soil micro-food web, and advance our understanding of multi-trophic interactions in terrestrial ecosystems.