Infilled Ditches are Hotspots of Landscape Methane Flux Following Peatland Re-wetting
Infilled Ditches are Hotspots of Landscape Methane Flux Following Peatland Re-wetting
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DOI：
10.1007/s10021-014-9791-3
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发表时间：
2014-11-01
期刊：
影响因子：
3.7
通讯作者：
Freeman, Christopher
中科院分区：
文献类型：
--
作者：
Cooper, Mark. D. A.;Evans, Christopher. D.;Freeman, Christopher
泥炭地是陆地上巨大的碳储存库和持续的二氧化碳汇，但在上个世纪，大片地区被用于农业和林业，可能将其转化为净碳源。最近，一些泥炭地通过堵塞排水沟重新湿润，目的是增强生物多样性，减轻洪水，促进碳储存。泥炭地再湿润的一个潜在有害后果是甲烷（CH4）排放的增加，抵消了增加的二氧化碳固存的好处。我们研究了用沟渠排水的地毯式沼泽区域与最近填满排水沟的邻近区域之间CH4排放的差异。结果表明，阴道菌的定殖导致了填埋沟渠本身CH4排放的“热点”，而其他再湿润区域的CH4增加较小。外推到研究地点周围的毯状沼泽区域，我们估计排水前CH4排放量约为60 kg CH4 ha(-1) y(-1)，排水后减少到44 kg CH4 ha(-1) y（-1）。我们计算出，完全重新湿润这一地区最初将使排放量增加到约120 kg CH4 ha(-1) y（-1）的峰值，其中约三分之二的增加（与排水前条件相比增加的90%）归因于阴道杆菌聚集的填充沟渠的CH4排放，尽管这些区域仅占景观的7%。我们预测，随着生态系统的恢复，排放量最终会下降到排水前的值，但前提是泥鳅苔藓取代了填满沟渠的阴道藓。这些结果对缓解气候变化的泥炭地管理具有启示意义，表明恢复方法应尽可能以避免充气生物（如阴道芽孢杆菌）在填满的沟渠中定植为目标，并鼓励泥炭草的建立。
Peatlands are large terrestrial stores of carbon, and sustained CO2 sinks, but over the last century large areas have been drained for agriculture and forestry, potentially converting them into net carbon sources. More recently, some peatlands have been re-wetted by blocking drainage ditches, with the aims of enhancing biodiversity, mitigating flooding, and promoting carbon storage. One potential detrimental consequence of peatland re-wetting is an increase in methane (CH4) emissions, offsetting the benefits of increased CO2 sequestration. We examined differences in CH4 emissions between an area of ditch-drained blanket bog, and an adjacent area where drainage ditches were recently infilled. Results showed that Eriophorum vaginatum colonization led to a "hotspot'' of CH4 emissions from the infilled ditches themselves, with smaller increases in CH4 from other re-wetted areas. Extrapolated to the area of blanket bog surrounding the study site, we estimated that CH4 emissions were around 60 kg CH4 ha(-1) y(-1) prior to drainage, reducing to 44 kg CH4 ha(-1) y(-1) after drainage. We calculated that fully re-wetting this area would initially increase emissions to a peak of around 120 kg CH4 ha(-1) y(-1), with around two-thirds of the increase (and 90% of the increase over pre-drainage conditions) attributable to CH4 emissions from E. vaginatum-colonized infilled ditches, despite these areas only occupying 7% of the landscape. We predicted that emissions should eventually decline toward pre-drainage values as the ecosystem recovers, but only if Sphagnum mosses displace E. vaginatum from the infilled ditches. These results have implications for peatland management for climate change mitigation, suggesting that restoration methods should aim, if possible, to avoid the colonization of infilled ditches by aerenchymatous species such as E. vaginatum, and to encourage Sphagnum establishment.