Unveiling sedimentary microbial communities: Restored mangrove wetlands show higher heterogeneity and network stability than natural ones

Mangrove wetlands, characterized by high biodiversity and crucial ecological functions, have witnessed extensive restoration efforts in China in recent decades. Despite the successful recovery of standing vegetation, the alterations in below-ground microbial communities, vital engines for completing biogeochemical cycles in wetlands, remain poorly understood. Here, the prokaryotic and microeukaryotic communities in restored mangrove forests (RMF) and natural mangrove forests (NMF) in Shenzhen, the world’s first International Mangrove Center in China were investigated and compared. This work aimed to explore an appropriate sampling strategy for sedimentary microbial community biodiversity study and evaluate their heterogeneity and network stability in RMF and NMF. The results revealed that a “broad-coverage and sparse-spot” sampling strategy was conducive to ensuring a sufficient representation of microbial diversity in mangrove wetlands. Significant differences were found in microbial community structures of RMF and NMF, with the relative abundances of Myxococcales and Cerozoa as potential biomarkers, respectively. RMF displayed higher prokaryotic richness, microbial community dissimilarity, and spatial turnover rate compared to those of NMF, indicating greater microbial diversity and spatial heterogeneity in RMF. Meanwhile, the RMF microbial network was characterized by lower complexity but higher modularity, robustness, and the ratio of negative to positive cohesion. These demonstrated that microbiomes were shaped by stability constraints and the RMF microbial network was more stable and resistant to environmental variations than that of NMF. Interestingly, the stability of these microbial networks appeared to depend on the topological roles of key species rather than on their abundance. Overall, this study disclosed a kind of relationship between the aboveground elements of restored and natural mangrove forests and their belowground microbial communities. These findings provide references for comprehensive assessments of biodiversity, stability, and ecological restoration in mangrove ecosystems.