Abstract: Sulfate-reducing bacteria (SRB) and sulfur-oxidizing bacteria (SOB) play important roles in the sulfur cycle of coastal salt marsh sediments. SRB can reduce sulfate to sulfide, while SOB can oxidize the reduced sulfur compounds to sulfate and decrease the accumulation of sulfide. Both of them can keep the dynamics of sulfur cycle in balance. This paper summarized the research progress on the existent forms of sulfur in coastal salt marsh sediments, its geochemical cycle, and the biodiversity, bioactivity, and ecological significance of SRB and SOB. Some issues involved in the sulfur cycle in coastal salt marsh ecosystem and the ongoing research on the functions of SRB and SOB in this ecosystem were discussed.

Key words: Xiaoxing′anling forest region, Forest harvesting, Runoff, Peak flood, Snowmelt runoff amount