title: Aerobic methane emission from plants in the Inner Mongolia steppe.
abstract: Traditionally, methane (CH4) emission from terrestrial plants is thought to originate from belowground microbial metabolism under anaerobic conditions, with subsequent transport to the atmosphere through stems. However, a recent study reported aerobic CH4 emission from plants by an unrecognized process, a result that has since been questioned. We investigated CH4 emissions under aerobic conditions from aboveground tissues of 44 species indigenous to the temperate Inner Mongolia steppe. Ten herbaceous hydrophytes (wetland-adapted plants) were examined, two of which--Glyceria spiculosa and Scirpus yagara--emitted CH4 from stems but not from detached leaves. Of 34 xerophytes (arid-adapted plants) examined, 7 out of 9 shrub species emitted CH4 from detached leaves but not stems, whereas none of 25 herbaceous xerophytes emitted CH4. The herbaceous hydrophyte, S. yagara, emitted highly 13C-depleted CH4, suggesting a microbial origin. Achillea frigida exhibited the highest CH4 emission rates among the shrubs and continuously emitted relatively 13C-enriched CH4 from detached leaves, indicating that CH4 was derived directly from plant tissues under aerobic conditions. Because woody species are relatively rare in the Inner Mongolia steppe, aerobic, plant-derived CH4 emission is probably negligible in this region. Our results may imply a larger role for aerobic CH4 production in upland ecosystems dominated by woody species or in ecosystems where woody encroachment is occurring as a result of global change.
authors: State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Nanxincun 20, Xiangshan, Beijing 100093, China. wangzp5@yahoo.com
authors: Zhi-Ping
authors: ZP
authors: Wang
authors: Xing-Guo
authors: XG
authors: Han
authors: G Geoff
authors: GG
authors: Wang
authors: Yang
authors: Y
authors: Song
authors: Jay
authors: J
authors: Gulledge
mesh_terms: D000332:Aerobiosis; D000393:Air Pollutants / Q000378:metabolism*; D002247:Carbon Isotopes / Q000032:analysis; D002681:China; D004784:Environmental Monitoring; D008697:Methane / Q000378:metabolism*; D010944:Plants / Q000378:metabolism*
chemical_list: D000393:Air Pollutants; D002247:Carbon Isotopes; D008697:Methane