Spartina alterniflora has the highest methane emissions in a St. Lawrence estuary salt marsh
Spartina alterniflora has the highest methane emissions in a St. Lawrence estuary salt marsh
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DOI：
10.1088/2752-664x/ac706a
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发表时间：
2022-05
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影响因子：
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通讯作者：
S. Comer-Warner;Sami Ullah;Wendy Ampuero Reyes;S. Krause;G. Chmura
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作者：
S. Comer-Warner;Sami Ullah;Wendy Ampuero Reyes;S. Krause;G. Chmura
盐沼有能力储存大量的“蓝碳”，有可能减轻气候变化的一些影响。盐沼的碳储存可能部分被甲烷（一种强效温室气体）的排放所抵消。海平面上升和植被入侵可能导致盐沼生态系统不同海拔和植被带之间的转移。海拔高度带具有不同的土壤性质、植物性状和根际特征，影响CH4通量。我们调查了典型的盐沼在西北大西洋北方的四个海拔区（泥滩，互花米草，Spartina patens和入侵芦苇）之间的CH4排放量的差异。S.互花米草区（17.7 ± 9.7 mg C m − 2h − 1）与其他三个排放量可忽略不计（<0.3 mg C m − 2h − 1）的区域相比。这些排放量很高的盐沼和那些通常发现在低盐度的寡盐沼泽相似。CH4通量与土壤性质（盐度、地下水位深度、容重和温度）、植物性状（根茎体积和生物量、根体积和死生物量）和CO2通量显著相关。CH4排放量和根茎和根体积之间的关系表明，在这些植物的通气组织可能是一个主要的运输机制CH4从缺氧土壤到大气中。这可能对全球盐沼碳汇的减排潜力产生重大影响，特别是作为S。互花米草分布广泛。这项研究表明，CH4通量可以在同一系统中不同植被的数量级上变化，因此，在未来的气候模型中可能需要使用特定的排放因子，并根据植被类型进行更准确的碳预算。
Salt marshes have the ability to store large amounts of ‘blue carbon’, potentially mitigating some of the effects of climate change. Salt marsh carbon storage may be partially offset by emissions of CH4, a highly potent greenhouse gas. Sea level rise and invasive vegetation may cause shifts between different elevation and vegetation zones in salt marsh ecosystems. Elevation zones have distinct soil properties, plant traits and rhizosphere characteristics, which affect CH4 fluxes. We investigated differences in CH4 emissions between four elevation zones (mudflat, Spartina alterniflora, Spartina patens and invasive Phragmites australis) typical of salt marshes in the northern Northwest Atlantic. CH4 emissions were significantly higher from the S. alterniflora zone (17.7 ± 9.7 mg C m−2h−1) compared to the other three zones, where emissions were negligible (<0.3 mg C m−2h−1). These emissions were high for salt marshes and were similar to those typically found in oligohaline marshes with lower salinities. CH4 fluxes were significantly correlated with soil properties (salinity, water table depth, bulk density and temperature), plant traits (rhizome volume and biomass, root volume and dead biomass volume all at 0–15 cm) and CO2 fluxes. The relationships between CH4 emissions, and rhizome and root volume suggest that the aerenchyma tissues in these plants may be a major transport mechanism of CH4 from anoxic soils to the atmosphere. This may have major implications for the mitigation potential carbon sink from salt marshes globally, especially as S. alterniflora is widespread. This study shows CH4 fluxes can vary over orders of magnitude from different vegetation in the same system, therefore, specific emissions factors may need to be used in future climate models and for more accurate carbon budgeting depending on vegetation type.