Fresh Air for the Mire-Breathing Hypothesis: Sphagnum Moss and Peat Structure Regulate the Response of CO2 Exchange to Altered Hydrology in a Northern Peatland Ecosystem
Fresh Air for the Mire-Breathing Hypothesis: Sphagnum Moss and Peat Structure Regulate the Response of CO2 Exchange to Altered Hydrology in a Northern Peatland Ecosystem
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DOI：
10.3390/w14203239
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发表时间：
2022-10
期刊：
影响因子：
3.4
通讯作者：
Ally O’Neill;C. Tucker;E. Kane
中科院分区：
文献类型：
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作者：
Ally O’Neill;C. Tucker;E. Kane
泥炭地储存的碳比地球上所有的森林都多，在二氧化碳平衡中发挥着重要作用。然而，这些碳汇面临着一个不确定的未来，因为气候变化可能会导致水资源紧张，可能会降低泥炭藓的生产力，并将泥炭地转变为碳源。从两个泥炭地地貌：隆起的土丘（丘）和较低的，平坦的地区的泥炭地（凹地）收集的32个泥炭芯进行了围隔实验。降雨处理和地下水位进行了操纵，和CO2通量进行了测量。其他研究观察到泥炭下沉，并跟踪水位下降时，经历水压力，被认为是一种自我保护的技术称为“沼泽呼吸”。然而，我们发现，丘倾向于向内压缩，而不是像空洞那样显著地向地下水位下降下沉。较低的泥炭高度与降低总初级生产力（GPP）在响应降低地下水位，表明泥炭沉降并没有显着提高GPP的抗旱性呈线性相关。相反，泥炭藓泥炭压缩被发现稳定GPP，这表明这种机制的弹性干旱可能会传输整个景观，这取决于泥炭藓地貌类型占主导地位。这项研究得出泥炭藓性状和泥炭地水文和碳循环之间的直接联系。
Sphagnum-dominated peatlands store more carbon than all of Earth’s forests, playing a large role in the balance of carbon dioxide. However, these carbon sinks face an uncertain future as the changing climate is likely to cause water stress, potentially reducing Sphagnum productivity and transitioning peatlands to carbon sources. A mesocosm experiment was performed on thirty-two peat cores collected from two peatland landforms: elevated mounds (hummocks) and lower, flat areas of the peatland (hollows). Both rainfall treatments and water tables were manipulated, and CO2 fluxes were measured. Other studies have observed peat subsiding and tracking the water table downward when experiencing water stress, thought to be a self-preservation technique termed ‘Mire-breathing’. However, we found that hummocks tended to compress inwards, rather than subsiding towards the lowered water table as significantly as hollows. Lower peat height was linearly associated with reduced gross primary production (GPP) in response to lowered water tables, indicating that peat subsidence did not significantly enhance the resistance of GPP to drought. Conversely, Sphagnum peat compression was found to stabilize GPP, indicating that this mechanism of resilience to drought may transmit across the landscape depending on which Sphagnum landform types are dominant. This study draws direct connections between Sphagnum traits and peatland hydrology and carbon cycling.