The Role of the Upper Tidal Estuary in Wetland Blue Carbon Storage and Flux
The Role of the Upper Tidal Estuary in Wetland Blue Carbon Storage and Flux
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DOI：
10.1029/2018gb005897
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发表时间：
2018-05-01
影响因子：
5.2
通讯作者：
Whitbeck, Julie L.
中科院分区：
文献类型：
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作者：
Krauss, Ken W.;Noe, Gregory B.;Whitbeck, Julie L.
碳（C）常量储量、碳质量平衡和潮汐淡水森林湿地（TFFW）中的土壤碳埋藏以及沿河口上游过渡到低盐度沼泽的 TFFW 通常不包括在蓝碳核算中，但可能代表重要的碳汇。美国大西洋沿岸潮汐瓦卡莫河和萨凡纳河沿线的两条盐度样带的结果表明，所有地点的总碳储量为 322-1,264 毫克碳/公顷，随着盐度的增加，通常会转向更大的土壤储存。长达11年的碳质量平衡输入（凋落物、木本生长、草本生长、根部生长和表面积累）减去碳输出（表面凋落物和根部分解、气态C）为340-900g Cm(-2)年(-1)。土壤碳埋藏量是可变的（7-337g Cm(-2)年(-1)），侧向碳输出估计为碳质量平衡减去土壤碳埋藏量，即267-849g Cm(-2)年(-1)。这代表着大量的碳输出以支持水生生物地球化学转化。尽管挺水植被内的碳持久性降低、有机质分解以及横向碳输出增加，但随着森林盐化转变为沼泽，总碳储存量增加。这些潮汐河流湿地在盐分胁迫的森林地区表现出高氮矿化，在低盐度沼泽中表现出大量磷矿化。大量的碳常备储量和碳封存率表明，TFFW 和寡盐沼泽对于全球沿海碳动态以及促进其所在地区的能源转型相当重要。 通俗语言摘要 在确定陆地生态系统储存、交换或输出的碳量时，通常不考虑沿河流相关河口上游出现的潮汐湿地 全球。这些湿地类型的例子包括潮汐淡水森林湿地和低盐度沼泽，以及随着盐度入侵和海平面上升而处于森林和沼泽之间过渡不同阶段的湿地。然而，这些潮汐湿地比世界各地记录的许多沿海湿地类型（包括经典定义的蓝碳湿地）储存的碳更多，并且它们支持高年固碳率（从大气中吸收二氧化碳）和横向碳输出到水生环境，这可能影响关键的近岸和海洋能源转换。
Carbon (C) standing stocks, C mass balance, and soil C burial in tidal freshwater forested wetlands (TFFW) and TFFW transitioning to low-salinity marshes along the upper estuary are not typically included in blue carbon accounting, but may represent a significant C sink. Results from two salinity transects along the tidal Waccamaw and Savannah rivers of the U.S. Atlantic Coast show that total C standing stocks were 322-1,264Mg C/ha among all sites, generally shifting to greater soil storage as salinity increased. Carbon mass balance inputs (litterfall, woody growth, herbaceous growth, root growth, and surface accumulation) minus C outputs (surface litter and root decomposition, gaseous C) over a period of up to 11years were 340-900g Cm(-2)year(-1). Soil C burial was variable (7-337g Cm(-2)year(-1)), and lateral C export was estimated as C mass balance minus soil C burial as 267-849g Cm(-2)year(-1). This represents a large amount of C export to support aquatic biogeochemical transformations. Despite reduced C persistence within emergent vegetation, decomposition of organic matter, and higher lateral C export, total C storage increased as forests converted to marsh with salinization. These tidal river wetlands exhibited high N mineralization in salinity-stressed forested sites and considerable P mineralization in low-salinity marshes. Large C standing stocks and rates of C sequestration suggest that TFFW and oligohaline marshes are considerably important globally to coastal C dynamics and in facilitating energy transformations in areas of the world in which they occur.Plain Language Summary Tidal wetlands that occur along the upper reaches of river-associated estuaries are not normally considered when determining the amount of carbon stored, exchanged, or exported from terrestrial ecosystems globally. Examples of these wetland types include tidal freshwater forested wetlands and low-salinity marshes, as well as wetlands at different stages of transition between forest and marsh as salinity intrudes and sea levels rise. However, these tidal wetlands store more carbon than many coastal wetland types documented throughout the world, including classically defined blue carbon wetlands, and they support high rates of annual carbon sequestration (uptake of CO2 from the atmosphere) and lateral carbon export into aquatic environments that can influence critical near-shore and marine energy transformations.