Wetland carbon storage controlled by millennial-scale variation in relative sea-level rise
Wetland carbon storage controlled by millennial-scale variation in relative sea-level rise
复制标题
DOI：
10.1038/s41586-019-0951-7
复制
发表时间：
2019-03-07
期刊：
影响因子：
64.8
通讯作者：
Woodroffe, Colin D.
中科院分区：
文献类型：
--
作者：
Rogers, Kerrylee;Kelleway, Jeffrey J.;Woodroffe, Colin D.
沿海湿地（红树林、潮汐沼泽和海草）是所有自然系统中单位面积碳固存率最高的（1,2），这主要是因为它们的生产力相对较高，并能在沉积基质中保存有机碳(3)。气候变化和相关的相对海平面上升（RSLR）在21世纪上半叶增加了沿海湿地的有机碳埋藏率(4)，但这些碳-气候反馈效应已被模拟为随着时间的推移而减弱，因为湿地越来越被淹没，碳储存受到侵蚀（4,5）。在这里，我们表明，在过去的几千年里（在全新世晚期，从大约4200年前到现在），海岸线上的潮汐沼泽经历了快速的RSLR，其表面20厘米内的土壤碳浓度平均比那些长期海平面稳定的土壤碳浓度高1.7到3.7倍。这种差异随着深度的增加而增加，土壤碳浓度在50到100厘米的深度下降了4.9到9.1倍。我们分析了一个暴露在近期快速RSLR下的湿地在与下伏矿山矿柱坍塌相关的沉降后的反应，并证明了碳积累和海拔的增加与RSLR创造的容纳空间（即可用于矿物和有机物质积累的空间）成正比。研究结果表明，以构造稳定海岸线为特征的滨海湿地由于缺乏调节空间，其碳储量较低，而碳固存则随着RSLR创造的垂直和横向调节空间的增加而增加(6)。这样的湿地将提供与全球气候-碳模型相关的长期缓解反馈效应。
Coastal wetlands (mangrove, tidal marsh and seagrass) sustain the highest rates of carbon sequestration per unit area of all natural systems(1,2), primarily because of their comparatively high productivity and preservation of organic carbon within sedimentary substrates(3). Climate change and associated relative sea-level rise (RSLR) have been proposed to increase the rate of organic-carbon burial in coastal wetlands in the first half of the twenty-first century(4), but these carbon-climate feedback effects have been modelled to diminish over time as wetlands are increasingly submerged and carbon stores become compromised by erosion(4,5). Here we show that tidal marshes on coastlines that experienced rapid RSLR over the past few millennia (in the late Holocene, from about 4,200 years ago to the present) have on average 1.7 to 3.7 times higher soil carbon concentrations within 20 centimetres of the surface than those subject to a long period of sea-level stability. This disparity increases with depth, with soil carbon concentrations reduced by a factor of 4.9 to 9.1 at depths of 50 to 100 centimetres. We analyse the response of a wetland exposed to recent rapid RSLR following subsidence associated with pillar collapse in an underlying mine and demonstrate that the gain in carbon accumulation and elevation is proportional to the accommodation space (that is, the space available for mineral and organic material accumulation) created by RSLR. Our results suggest that coastal wetlands characteristic of tectonically stable coastlines have lower carbon storage owing to a lack of accommodation space and that carbon sequestration increases according to the vertical and lateral accommodation space(6) created by RSLR. Such wetlands will provide long-term mitigating feedback effects that are relevant to global climate-carbon modelling.