Soil organic carbon storages and bacterial communities along a restored mangrove soil chronosequence in the Jiulong River Estuary: From tidal flats to mangrove afforestation

for mangroves with afforestation ages of 36 and 60 years, respectively. The total nitrogen (TN) and total sulfur (TS) contents exhibited significant correlations with the SOC in the mangrove soils, but only TN and SOC showed significant correlation in tidal flat soils. Although the tidal flats and mangroves occupied the contiguous intertidal zone within several kilometers, the variations in the SOC storage along the restored mangrove soil chronosequence were notably higher. The Functional Annotation of Prokaryotic Taxa (FAPROTAX) database was used to annotate the metabolic functions of the bacteria in the soils. The annotation revealed that only four metabolic functions were enriched with a higher relative abundance of the corresponding bacteria, and these enriched functions were largely associated with sulfate reduction. In addition, the specifically critical bacterial taxa that were associated with the SOC accumulation and nutrient cycling, shaped the distinct metabolic functions, and consequently facilitated the SOC accumulation in the mangrove soils with various afforestation ages. The general homogenization of the microbial community and composition along the intertidal soil chronosequence was primarily driven by the reciprocating tidal flows and geographical contiguity.