A three-year study of controls on methane emissions from two Michigan peatlands
A three-year study of controls on methane emissions from two Michigan peatlands
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DOI：
10.1007/bf00002570
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发表时间：
1994
期刊：
影响因子：
4
通讯作者：
R. Shannon;J. R. White
中科院分区：
文献类型：
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作者：
R. Shannon;J. R. White
我们调查了密歇根州两个泥炭地三年期间甲烷排放量的时间变化。在以豆科灌木茶树为主的植物群落中，CH4m−2d−1的日平均通量为0.60-68.4mgCH4m−2d−1，在以少花苔草和沼泽苔草等植物为主的区域中，日平均通量为11.5-209mgCH4m 2d−1。当地下水位波动范围为泥炭地表以上15 cm到地下50 cm时，所有站点的甲烷通量与地下水位位置在一年周期内均显著相关。在地下水位波动较小的第二和第三年期间，相关性不显著。在植物区系作为甲烷输送管道的3年中，甲烷通量与−5~−40 cm范围内的泥炭温度密切相关(r=0.82~0.98)。在灌木区，甲烷通量与泥炭温度的相关性在头两年很弱到不显著，但在第三年表现出很强的相关性。当地下水位低于−20 cm时，灌木区的甲烷消耗速率(−0.2mgCH4m−2d−1)很低，而具有甲烷输送能力的植物的甲烷净通量总是为正的。泥炭岩心实验证实了这两类地点的甲烷氧化潜势。这项研究的结果表明，甲烷的排放速率不能仅用扩散来解释；植物群落通过将甲烷从厌氧泥炭直接输送到大气中，在改变泥炭生态系统的甲烷通量方面发挥了重要作用。
We investigate temporal changes in methane emissions over a three-year period from two peatlands in Michigan. Mean daily fluxes ranged from 0.6–68.4 mg CH4m−2d−1in plant communities dominated byChamaedaphne calyculata, an eficaceous shrub, to 11.5–209 mg CH4m−2d−1in areas dominated by plants with aerenchymatous tissues, such asCarex oligospermaandScheuchzeria palustris. Correlations between methane flux and water table position were significant at all sites for one annual cycle when water table fluctuations ranged from 15 cm above to 50 cm below the peat surface. Correlations were not significant during the second and third annual periods with smaller water table fluctuations. Methane flux was strongly correlated with peat temperatures at −5 to −40 cm (rs= 0.82 to 0.98) for all three years at sites with flora acting as conduits for methane transport. At shrub sites, the correlations between methane flux and peat temperature were weak to not significant during the first two years, but were strong in the third year.Low rates of methane consumption (−0.2 to −1.5 mg CH4m−2d−1) were observed at shrub sites when the water table was below −20 cm, while sites with plants capable of methane transport always had positive net fluxes of methane. The methane oxidizing potential at both types of sites was confirmed by peat core experiments. The results of this study indicate that methane emissions occur at rates that cannot be explained by diffusion alone; plant communities play a significant role in altering methane flux from peatland ecosystems by directly transporting methane from anaerobic peat to the atmosphere.