Saarnio S, Silvola J
Department of Biology, University of Joensuu, P.O. Box 111, FIN-80101 Joensuu, Finland e-mail:
Oecologia. 1999 May;119(3):349-356. doi: 10.1007/s004420050795.
Increases in the supply of atmospheric CO and N are expected to alter the carbon cycle, including CH emissions, in boreal peatlands. These effects were studied in a glasshouse experiment with peat monoliths cored from an oligotrophic pine fen. The cores with living plants were kept in 720 ppm and 360 ppm CO atmospheres for about 6 months under imitated natural temperature cycle. Fertilisation with NHNO (3 g m for 25 weeks) was applied to 18 of the 36 monoliths. The rate of CH flux was non-linearly dependent on the number of Eriophorum vaginatum shoots growing in the monoliths, probably due to the gas transport properties of the aerenchyma. The average CH efflux rate, standardised by the number of shoots, was increased by a maximum of 10-20% in response to the raised CO level. In the raised-NHNO treatment, the increase in CH release was lower. The effect of combined CO+NHNO on CH release was negligible and even lower than in the single treatments. Both potential CH production and oxidation rates at 5, 15 and 25°C were higher near the surface than at the bottom of the core. As expected, the rates clearly depended on the incubation temperature, but the different treatments did not cause any consistent differences in either CH production or oxidation. The determination of potential CH production and oxidation in the laboratory is evidently too crude a method of differentiating substrate-induced differences in CH production and oxidation in vivo. These results indicate that an increase in atmospheric CO or N supply alone, at least in the short term, slightly enhances CH effluxes from boreal peatlands; but together their effect may even be restrictive.
预计大气中二氧化碳（CO）和氮（N）供应量的增加将改变北方泥炭地的碳循环，包括甲烷（CH）排放。在一项温室实验中，研究了这些影响，该实验使用了从贫营养松树沼泽地采集的泥炭整块样本。将带有活植物的样本在模拟自然温度循环条件下，置于720 ppm和360 ppm的CO气氛中约6个月。对36个整块样本中的18个施加硝酸铵（3 g m，持续25周）进行施肥。CH通量速率与整块样本中生长的绒毛草茎的数量呈非线性相关，这可能是由于通气组织的气体传输特性所致。以茎的数量进行标准化后，平均CH排放速率因CO水平升高而最多增加了10 - 20%。在提高硝酸铵处理中，CH释放的增加幅度较小。CO + 硝酸铵联合处理对CH释放的影响可忽略不计，甚至低于单一处理。在5℃、15℃和25℃时，表层附近的潜在CH产生和氧化速率均高于样本底部。正如预期的那样，这些速率明显取决于培养温度，但不同处理在CH产生或氧化方面并未导致任何一致的差异。在实验室中测定潜在的CH产生和氧化显然是一种过于粗略的方法，无法区分体内底物诱导的CH产生和氧化差异。这些结果表明，仅大气中CO或N供应量的增加，至少在短期内，会略微增强北方泥炭地的CH排放；但它们共同作用的效果甚至可能具有限制性。
