Topological Reinforcement of Rhizosphere Microbial Networks Facilitates the Invasive Superiority of Spartina anglica

Abstract

Rhizosphere microbial interaction patterns underpin the resilience and dominance of invasive plants in fluctuating coastal salt marshes. We compared the rhizosphere microbial communities of the invasive Spartina anglica and the native Spartina maritima across varying distances from freshwater inputs using 16 S rRNA high throughput sequencing and co-occurrence network analysis. S. anglica maintained high rhizosphere microbial taxonomic stability across all locations, whereas S. maritima displayed significant shifts in microbial community composition in response to environmental variation. Despite this taxonomic consistency, S. anglica adaptively rewired its microbial network topology to maintain functional robustness. At distal locations (farther from the freshwater stream) characterized by high abiotic stress, S. anglica rhizosphere networks exhibited significantly higher density, nodal connectivity, and topological complexity. Conversely, S. maritima suffered a substantial reduction in network organizational stability and complexity under identical conditions. These results suggest that the invasive success of S. anglica may be linked to its ability to engineer a cooperative and resilient microbial interaction environment via topological reinforcement, although further studies across seasonal and temporal scales are needed to confirm this relationship. This research highlights that the structural organization of microbial networks, rather than changes in taxonomic recruitment, determines the competitive superiority of invasive species in dynamic coastal ecosystems.