Declines in Plant Productivity Drive Carbon Loss from Brackish Coastal Wetland Mesocosms Exposed to Saltwater Intrusion
Declines in Plant Productivity Drive Carbon Loss from Brackish Coastal Wetland Mesocosms Exposed to Saltwater Intrusion
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DOI：
10.1007/s12237-018-0438-z
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发表时间：
2018-07
影响因子：
2.7
通讯作者：
B. Wilson;S. Servais;Sean P. Charles;S. E. Davis;E. Gaiser;J. Kominoski;J. Richards;T. Troxler
中科院分区：
文献类型：
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作者：
B. Wilson;S. Servais;Sean P. Charles;S. E. Davis;E. Gaiser;J. Kominoski;J. Richards;T. Troxler
沿海湿地是生产力最高的生态系统之一，是全球重要的碳库（C）。海平面加速上升（SLR）和沿海湿地的咸水入侵增加了盐度和淹没深度，对驱动碳储存的植物和土壤过程造成不确定的影响。我们将来自咸湿沼泽的带有锯草（Cladium jamaicense）植物的泥炭土块暴露在盐度（升高（约 20 ppt）与环境（约 10 ppt））和淹没水平（淹没（土壤表面以上的水）与暴露（土壤表面以下 4 厘米的水位））的持续处理中 18 个月。我们量化了土壤生物地球化学、植物生产力和整个生态系统碳通量（生态系统总生产力，GEP；生态系统呼吸，ER）的变化。盐度升高对土壤CO 2 和CH 4 流出没有影响，但使ER和GEP分别降低42%和72%。暴露于环境盐度的对照巨石具有更高的净生态系统生产力（NEP），其储存的碳比暴露于高盐度的植物和土壤多九倍。淹没抑制了土壤CO 2 外流，但对NEP没有影响。咸水入侵导致植物生产力和土壤有机碳输入下降，可能是土壤碳储存量净下降的机制，这可能会影响沿海泥炭沼泽适应海平面上升的能力。
Coastal wetlands, among the most productive ecosystems, are important global reservoirs of carbon (C). Accelerated sea level rise (SLR) and saltwater intrusion in coastal wetlands increase salinity and inundation depth, causing uncertain effects on plant and soil processes that drive C storage. We exposed peat-soil monoliths with sawgrass (Cladium jamaicense) plants from a brackish marsh to continuous treatments of salinity (elevated (~ 20 ppt) vs. ambient (~ 10 ppt)) and inundation levels (submerged (water above soil surface) vs. exposed (water level 4 cm below soil surface)) for 18 months. We quantified changes in soil biogeochemistry, plant productivity, and whole-ecosystem C flux (gross ecosystem productivity, GEP; ecosystem respiration, ER). Elevated salinity had no effect on soil CO 2 and CH 4 efflux, but it reduced ER and GEP by 42 and 72%, respectively. Control monoliths exposed to ambient salinity had greater net ecosystem productivity (NEP), storing up to nine times more C than plants and soils exposed to elevated salinity. Submersion suppressed soil CO 2 efflux but had no effect on NEP. Decreased plant productivity and soil organic C inputs with saltwater intrusion are likely mechanisms of net declines in soil C storage, which may affect the ability of coastal peat marshes to adapt to rising seas.