Fig. 2

Diazotrophic community composition and specific diazotrophic taxa associated with NFR in mangrove sediments. a Taxonomic composition of diazotrophic communities across 10 depths of mangrove sediments. Bar width indicates relative abundance of OTUs from different taxa. b Taxonomic cladogram based on linear discriminant analysis (LDA-score >2.0) combined with effect size measurements (LEfSe), which classify discriminative taxa between surficial sediments (0–50 cm, blue) and deep sediments (50–100 cm, red). Moving from inside to outside, cladograms depict domain, phylum, class, order, family, and genus levels. Taxa with non-significant differences are represented as yellow circles. In legend, red * represents the diazotrophic genus having significantly positive correlation with NFR, while blue * represents the diazotrophic genus showing significantly negative correlation with NFR. *p < 0.05; **p < 0.01