<i>Aegilops tauschii</i> invasion modulates rhizosphere microbial life-history strategies and co-occurrence networks via shifts in soil resource availability

Abstract Plant invasion is one of the major drivers of global biodiversity loss. By altering soil microenvironments, it affects microbial interactions and ultimately reshapes ecosystem functions. Aegilops tauschii (Coss.), a dominant invasive weed in the winter wheat-growing regions of the Huang-Huai-Hai Plain, China, has expanded rapidly and poses a severe threat to wheat production. However, the mechanisms underlying its impacts on soil microbial community structure and interactions remain unclear. In this study, bulk and rhizosphere soil samples were collected along an invasion gradient (from uninvaded to severely invaded). By integrating analyses of soil physicochemical properties with microbial functional traits, we identified the key factors driving changes in microbial life-history strategies and co-occurrence networks. A. tauschii invasion significantly modified soil resources, with declining moisture and electrical conductivity but strong ammonium enrichment in bulk soil. Bacterial diversity showed U- or hump-shaped responses, while fungal diversity was weakly affected. Life-history traits shifted toward oligotrophy, particularly at severe invasion, whereas A. tauschii rhizosphere communities maintained more optimized strategy combinations. Network analysis revealed increased bacterial network complexity but reduced fungal stability in bulk soil, whereas A. tauschii rhizospheres developed more stable and complex bacterial networks. Electrical conductivity and ammonium nitrogen were identified as primary drivers of microbial diversity, strategy shifts, and network reorganization. The rhizosphere microbiome of A. tauschii establishes a belowground positive feedback loop facilitated by resource retention, strategy optimization, and enhanced network stability, ultimately promoting its invasive capacity.