Impact of manipulated drought and heavy rainfall events on peat mineralization processes and source‐sink functions of an acidic fen
Impact of manipulated drought and heavy rainfall events on peat mineralization processes and source‐sink functions of an acidic fen
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DOI：
10.1029/2008jg000853
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发表时间：
2009-06
影响因子：
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通讯作者：
M. Reiche;A. Hädrich;G. Lischeid;K. Küsel
中科院分区：
文献类型：
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作者：
M. Reiche;A. Hädrich;G. Lischeid;K. Küsel
[1]气候变化模型预测了北方温带地区未来几十年降水模式的变化。由此引起的水位波动可能会极大地影响泥炭地的源汇功能。在这里，我们操纵了酸性微营养沼泽的地下水位，使用干燥和再湿实验来模拟夏季干旱和暴雨，以估计泥炭分解和源汇功能的变化。我们发现，在最初的地下水位下降过程中，最活跃的表层中二氧化碳(CO2)的形成速率和胞外酶活性增加；然而，极端干燥并没有进一步增加这些活性。在更深层的含氧泥炭层中激发的活动并不会对二氧化碳排放产生实质性的影响。此外，还未检测到酚氧化酶活性。泥炭干燥后的再湿不会像在矿物土壤中那样导致二氧化碳冲刷。地下水位控制产生了更高的硝酸盐、铁和硫酸盐的有效性，并延长了甲烷形成的开始。硫酸盐被出口到附近的一条溪流中。我们的结论是，夏季干旱和暴雨等极端天气条件的增加可能不会影响碳的储存，反而会加强泥炭地对硝酸盐和亚铁的汇功能和对硫酸盐的源功能。
[1] Climate change models predict changes in precipitation patterns over the next several decades for northern temperate regions. Resulting fluctuations of the water level may drastically affect the source-sink functions of peatlands. Here, we manipulated the water table level in an acidic, minerotrophic fen using drying and rewetting experiments to simulate summer drought and heavy rainfalls to estimate changes in peat decomposition and source-sink functions. We found that carbon dioxide (CO2) formation rates and exoenzymatic activities increased in the most active surface layer during the initial water table drawdown; however, extreme drying did not further increase these activities. Activity stimulated in deeper oxygenated peat layers did not substantially contribute to CO2 emissions. Additionally, no phenol oxidase activity was determined. Rewetting of peat after drying did not lead to a CO2 flush like in mineral soils. Water table manipulations yielded a higher availability of nitrate, ferric iron, and sulfate and prolonged the onset of methane formation. Sulfate was exported to a nearby stream. We concluded that the increasing frequency of extreme weather conditions like summer droughts and heavy rainfalls might not affect carbon storage but instead strengthen the sink function for nitrate and ferrous iron and the source function for sulfate in peatlands.