Water salinity and inundation control soil carbon decomposition during salt marsh restoration: an incubation experiment

Coastal wetlands are a significant carbon (C) sink since they store carbon in anoxic soils. This ecosystem service is impacted by hydrologic alteration and management of these ecosystems. Efforts to restore tidal flow to former salt marshes has increased in recent decades, and is generally associated with alteration of water inundation levels and salinity. This study examined the effect of water level and salinity changes on soil organic matter decomposition during a 60-day incubation period. Intact soil cores from impounded freshwater marsh and salt marsh were incubated after addition of either seawater or fresh water under flooded and drained water levels. Elevating freshwater marsh salinity to 6 to 9 ppt enhanced CO2 emission by 50% -80% and most typically decreased CH4 emissions, whereas, decreasing the salinity from 26 ppt to 19 ppt in salt marsh soils had no effect on CO2 or CH4 fluxes. The effect from altering water levels was more pronounced with drained soil cores emitting ~10-...

海岸湿地是重要的碳（C）汇，因其能在缺氧土壤中储存碳。这种生态系统服务受水文改变及生态系统管理的影响。近几十年来，恢复原盐沼潮汐流的努力日益增多，这通常与水位淹没程度和盐度的改变相关。本研究在60天培养期内考察了水位和盐度变化对土壤有机质分解的影响。来自封闭淡水沼泽和盐沼的完整土壤芯，在添加海水或淡水后，于淹没和排水两种水位条件下进行培养。将淡水沼泽盐度提升至6-9 ppt可使CO₂排放量增加50%-80%，且通常会降低CH₄排放量；而将盐沼土壤盐度从26 ppt降至19 ppt，对CO₂或CH₄通量无显著影响。