Spartina alterniflora invasion impacts denitrifying community diversity and functioning in marsh soils

Abstract This study aimed to investigate soil denitrifying bacterial and fungal community structures and potential denitrification rates in the coastal marsh soils of Eastern China across Spartina alterniflora invasive gradients (i.e. native (Nat), native-Spartina coexisted (Ecot) and Spartina-dominated (Mono) vegetations, respectively). Plant biomass and soil chemical properties were also analyzed to understand the patterns of spatial variability of structure and function of denitrifier communities across the studied gradients. Results indicated that total, bacterial and fungal potential denitrification rates (TDR, BDR and FDR) were 5.5, 3.5 and 1.5 times greater respectively in the Mono soil than in the Nat soil. Denitrifying bacterial richness, evenness and α-diversity were 2.0, 1.3 and 1.3 times greater in the Mono soil than those in the Nat soil, while only the richness among denitrifying fungal community parameters was 1.4 times greater in the Mono soil than that in the Nat soil. Plant biomass, soil organic carbon and pH were the most important factors influencing denitrifying bacterial and fungal community structures and functions. Denitrifying bacterial community composition was related closely to BDR and TDR, while denitrifying fungal community composition was not related to FDR and TDR, thus showing that the denitrifying bacterial community is a better predictor of denitrification function following Spartina invasion.