摘要
一般认为自然来源的甲烷是在厌氧环境下形成的,而最近研究却发现在有氧环境下植物自身也能释放甲烷,这将对全球甲烷收支产生重大影响。但这一发现目前还存在很大争议,一些研究证实植物在有氧环境下能排放甲烷,果胶、聚半乳糖醛酸等含甲氧基官能团的组分是植物产生甲烷的主要来源物质,甚至纤维素、木质素等植物结构组分也能排放甲烷;而另一些研究却发现植物并不能排放甲烷或者排放速率极小,而观测到的植物甲烷排放可能来自于土壤中,即溶解有甲烷的土壤水分被被植物吸收并通过蒸腾或蒸发作用而排放到大气中。有氧环境下植物排放甲烷的机制仍不清楚,光照、温度、紫外辐射、机械损伤等环境胁迫可能是导致植物排放甲烷的重要原因,但这些因素的影响作用仍存在很大的不确定性。即使如此,一些研究仍对全球或区域植物甲烷排放的通量进行了估算,估计全球植物甲烷排放通量为10-236Tg.a-1。未来研究应在更多地区针对不同生境的各种植物是否排放甲烷进行独立检验,并在此基础上探讨植物排放甲烷的机制。
According to conventional knowledge,methane emission from natural sources is primarily produced by strictly anaerobic methanogen microbes. However,recent findings suggest that terrestrial plants may also emit methane under aerobic conditions,and this has far-reaching implications for the estimation of global methane budget. The findings are still heavily debated. Some research has shown that plants can emit methane under an aerobic environment,and that compounds like pectin or polygalacturaonic acid,which contain methoxyl groups,and other plant structure components such as cellulose and lignin,can function as precursors for the production of methane. Other researchers argued that methane emission by plant materials were zero or very small in quantity,and the measured methane emissions from plants may come from soil water,which contains dissolved methane and plants emit the dissolved methane into the atmosphere through transpiration,or evaporation. The mechanism for the methane emission from plants under aerobic conditions remains unknown,environmental stress such as light,temperature,UV radiation and physical injury may lead to significant methane emissions from plants,but these factors are still uncertain. Even so,fluxes on the global and regional methane emissions from plants were estimated,and the global estimated values vary between 10 and 236 Tg·a^-1. These controversies should be re-examined in independent studies through measuring plant methane emission in different habitats,and examining the mechanisms of methane emissions from plants in the future.
出处
《生态学报》
CAS
CSCD
北大核心
2010年第14期3812-3817,共6页
Acta Ecologica Sinica
基金
国家自然科学基金项目(30970486)
福建省高等学校新世纪优秀人才支持计划资助项目
关键词
甲烷
植物
有氧条件
环境胁迫
methane
plant
aerobic conditions
environmental stress
