Expansion of Ligularia virgaurea patches enhances soil bacterial and fungal diversity in alpine meadows of the Qinghai-Tibet Plateau by mediating soil resource heterogeneity

Grassland patchiness degradation poses an escalating threat to grassland ecosystem functions and biodiversity, particularly in alpine ecosystems. The rapid expansion of Ligularia virgaurea patches on the Qinghai-Tibet Plateau is creating grassland degradation and weakening their ecological function, yet how this process alters soil microbial communities and its key drivers remain unclear. In response to this concern, we analyzed the soil physicochemical properties and soil microbial communities within L. virgaurea patches of different densities and explored the impacts of L. virgaurea invasion and patches expansion on soil nutrients, enzyme activities, and soil microbial communities. The results of this study indicated that the expansion of L. virgaurea patches enriched more available resources within the patches. Specifically, the soil organic carbon (SOC) content increased by 4.3%, soil total nitrogen (TN) by 9.5%, and soil total phosphorus (TP) by 11.3% within the patches. The expansion of L. virgaurea patches promoted the diversity of soil bacteria and fungi, and enhanced the connectivity and complexity of microbial networks. Structural equation modelling indicated that L. virgaurea patches enhanced soil resource heterogeneity, indirectly affecting the abundance and diversity of soil bacteria and fungi. Furthermore, we identified pH, NO3−-N, and cellulase as common drivers of bacterial and fungal community changes. Overall, L. virgaurea patches enhance the soil resources heterogeneity, changing the composition of soil microbial communities within the patches and increasing soil microbial diversity by regulating the availability of soil resources. This study clarifies the changing characteristics and interrelationships of abiotic and biological soil properties during the expansion of L. virgaurea patches in alpine meadows, providing a theoretical foundation for the management of grasslands affected by poisonous plants.