U. S. Geological Survey, Woods Hole Coastal and Marine Science Center, Woods Hole, MA 02543, USA.
U. S. Geological Survey, Woods Hole Coastal and Marine Science Center, Woods Hole, MA 02543, USA.
Sci Total Environ. 2022 Nov 20;848:157682. doi: 10.1016/j.scitotenv.2022.157682. Epub 2022 Jul 31.
Coastal wetlands provide key ecosystem services, including substantial long-term storage of atmospheric CO in soil organic carbon pools. This accumulation of soil organic matter is a vital component of elevation gain in coastal wetlands responding to sea-level rise. Anthropogenic activities that alter coastal wetland function through disruption of tidal exchange and wetland water levels are ubiquitous. This study assesses soil vertical accretion and organic carbon accretion across five coastal wetlands that experienced over a century of impounded hydrology, followed by restoration of tidal exchange 5 to 14 years prior to sampling. Nearby marshes that never experienced tidal impoundment served as controls with natural hydrology to assess the impact of impoundment and restoration. Dated soil cores indicate that elevation gain and carbon storage were suppressed 30-70 % during impoundment, accounting for the majority of elevation deficit between impacted and natural sites. Only one site had substantial subsidence, likely due to oxidation of soil organic matter. Vertical and carbon accretion gains were achieved at all restored sites, with carbon burial increasing from 96 ± 33 to 197 ± 64 g C m y. The site with subsidence was able to accrete at double the rate (13 ± 5.6 mm y) of the natural complement, due predominantly to organic matter accumulation rather than mineral deposition, indicating these ecosystems are capable of large dynamic responses to restoration when conditions are optimized for vegetation growth. Hydrologic restoration enhanced elevation resilience and climate benefits of these coastal wetlands.
沿海湿地提供了关键的生态系统服务，包括在土壤有机碳库中大量长期储存大气 CO。这种土壤有机质的积累是沿海湿地对海平面上升做出响应而抬升的重要组成部分。通过干扰潮汐交换和湿地水位来改变沿海湿地功能的人为活动非常普遍。本研究评估了五个经历了一个多世纪的蓄水水文条件的沿海湿地的土壤垂直堆积和有机碳堆积，然后在采样前 5 到 14 年恢复了潮汐交换。附近从未经历过潮汐围堵的沼泽作为具有自然水文条件的对照，以评估围堵和恢复的影响。定年的土壤岩芯表明，在围堵期间，高程增加和碳储存受到了 30-70%的抑制，这占了受影响和自然地点之间高程差的大部分。只有一个地点发生了大量沉降，可能是由于土壤有机质的氧化。所有恢复的地点都实现了垂直和碳堆积的增加，碳埋藏量从 96 ± 33 增加到 197 ± 64 g C m y。沉降的地点的堆积速率是自然补偿的两倍（13 ± 5.6 mm y），这主要是由于有机质的积累而不是矿物质的沉积，表明这些生态系统在条件有利于植被生长时，能够对恢复做出较大的动态响应。水文恢复增强了这些沿海湿地的高程恢复能力和气候效益。
