Diversity and Life-History Strategies of Rhizosphere Microbial Communities Associated with Deyeuxia Angustifolia Along a Wetland Degradation Gradient

Abstract Wetland degradation alters rhizosphere habitats and resource availability, yet its effects on bacterial and fungal diversity and life-history strategies remain unclear. We examined Deyeuxia angustifolia rhizosphere communities across four wetland types in the Sanjiang Plain, China: marsh (ZZ), typical meadow (DC), slightly degraded (DN), and severely degraded (DS). We measured plant biomass and soil properties and analyzed microbial communities using 16 S rRNA gene and ITS amplicon sequencing, life-history strategy indices, and partial least-squares path modeling (PLS-PM). Bacterial and fungal community composition differed significantly among wetland types ( P ≤ 0.001 and P = 0.006, respectively). Bacterial alpha diversity did not differ significantly, whereas fungal Shannon and ACE indices were lower in DN than in DC ( P < 0.05). The relative abundances of Acidobacteriota and Archaeorhizomyces increased with degradation, whereas Pseudomonadota and Actinomycetota peaked in DC; Ascomycota dominated fungal communities. The bacterial oligotrophic-to-copiotrophic ratio was highest in ZZ, followed by DN, with both exceeding DC and DS ( P < 0.05). The fungal ectomycorrhizal-to-saprotrophic ratio showed no significant differences. PLS-PM indicated that degradation was negatively associated with soil environmental conditions ( P < 0.001), which were positively associated with the bacterial oligotrophic-to-copiotrophic ratio ( P < 0.05) and negatively associated with fungal alpha diversity ( P < 0.05). Overall, fungal diversity in the rhizosphere soil of Deyeuxia angustifolia differed significantly across the wetland degradation gradient. Bacterial life-history strategies showed a significant, non-linear shift among degradation stages, reflected in changes in the relative dominance of oligotrophic and copiotrophic taxa. These findings provide insight into how wetland microbial communities respond to degradation and may inform wetland restoration.