Standing Dead Trees: a Conduit for the Atmospheric Flux of Greenhouse Gases from Wetlands?

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• 作者：Mary Jane Carmichael ; William K. Smith
• 关键词：Dead vegetation ; Wetlands ; Carbon cycle ; Methane ; Decomposition ; Gas transport
• 刊名：Wetlands
• 出版年：2016
• 出版时间：December 2016
• 年：2016
• 卷：36
• 期：6
• 页码：1183-1188
• 全文大小：
• 刊物主题：Freshwater & Marine Ecology; Environmental Management; Ecology; Hydrogeology; Coastal Sciences; Landscape Ecology;
• 出版者：Springer Netherlands
• ISSN：1943-6246
• 卷排序：36

文摘

Wetlands represent the largest natural source of methane flux to the atmosphere, which can occur across the sediment/water/plant-atmosphere interface. Of these three potential methane sources, the role of vegetation in this flux is the least well understood. Both living and dead herbaceous vegetation have been demonstrated to act as methane sources, while knowledge regarding the contribution of woody vegetation to this flux is restricted to live plants. For dead woody vegetation to act as a methane source, two conditions must occur: (1) gas evolution/accumulation within the trunk airspace of a dead tree (e.g. snag) and (2) flux of this gas across the plant-atmosphere interface. The research presented here investigates condition (1) and provides evidence for a significant accumulation of both CH₄ and CO₂ in trunk airspace at water level (104.4 ± 19.0 and 1785.5 ± 470.7 μL L−1 for CH₄ and CO₂ respectively) and CO₂ at breast height (1257.6 ± 294.4 μL L−1) as compared to ambient air immediately outside the trunk (ca. 3 and 370 μL L−1 for CH₄ and CO₂ respectively) in dead snags located within two ghost forest landscapes at the Timberlake Observatory for Wetland Restoration (Tyrrell County, North Carolina). A more finely resolved understanding of this potential pathway for methane flux to the atmosphere is important given the predicted increase in dead carbon stocks within coastal wetland ecosystems, as global climate change can lead to the conversion of these ecosystems into ghost forest landscapes.