Department of Biology, Box 90338, Duke University, Durham, North Carolina 27708, USA.
Ecol Appl. 2012 Jan;22(1):264-80. doi: 10.1890/11-0527.1.
Whether through sea level rise or wetland restoration, agricultural soils in coastal areas will be inundated at increasing rates, renewing connections to sensitive surface waters and raising critical questions about environmental trade-offs. Wetland restoration is often implemented in agricultural catchments to improve water quality through nutrient removal. Yet flooding of soils can also increase production of the greenhouse gases nitrous oxide and methane, representing a potential environmental trade-off. Our study aimed to quantify and compare greenhouse gas emissions from unmanaged and restored forested wetlands, as well as actively managed agricultural fields within the North Carolina coastal plain, USA. In sampling conducted once every two months over a two-year comparative study, we found that soil carbon dioxide flux (range: 8000-64 800 kg CO2 x ha(-1) x yr(-1)) comprised 66-100% of total greenhouse gas emissions from all sites and that methane emissions (range: -6.87 to 197 kg CH4 x ha(-1) x yr(-1)) were highest from permanently inundated sites, while nitrous oxide fluxes (range: -1.07 to 139 kg N2O x ha(-1) x yr(-1)) were highest in sites with lower water tables. Contrary to predictions, greenhouse gas fluxes (as CO2 equivalents) from the restored wetland were lower than from either agricultural fields or unmanaged forested wetlands. In these acidic coastal freshwater ecosystems, the conversion of agricultural fields to flooded young forested wetlands did not result in increases in greenhouse gas emissions.
无论是海平面上升还是湿地恢复，沿海地区的农业土壤将以越来越快的速度被淹没，重新与敏感的地表水相连，并引发关于环境权衡的关键问题。湿地恢复通常在农业流域中实施，以通过去除养分来改善水质。然而，土壤的淹没也会增加温室气体一氧化二氮和甲烷的产生，这代表了一种潜在的环境权衡。我们的研究旨在量化和比较美国北卡罗来纳沿海平原未管理和恢复的森林湿地以及积极管理的农业领域的温室气体排放。在为期两年的对比研究中，我们每两个月进行一次采样，结果发现，土壤二氧化碳通量（范围：8000-64800kgCO2xha(-1)xyr(-1)）占所有地点温室气体总排放量的 66-100%，而甲烷排放量（范围：-6.87 至 197kgCH4xha(-1)xyr(-1)）最高的是永久性淹没的地点，而氮氧化物通量（范围：-1.07 至 139kgN2Oxha(-1)xyr(-1)）则在地下水位较低的地点最高。与预测相反，恢复湿地的温室气体通量（以 CO2 当量计）低于农业领域或未管理的森林湿地。在这些酸性沿海淡水生态系统中，将农业领域转换为淹没的年轻森林湿地并不会导致温室气体排放增加。
