Liu Huifeng, Wu Xing, Li Zongshan, Wang Qing, Liu Dan, Liu Guohua
State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China.
University of Chinese Academy of Science, Beijing, 100049, China.
Environ Sci Pollut Res Int. 2017 Mar;24(9):8731-8743. doi: 10.1007/s11356-017-8628-y. Epub 2017 Feb 17.
Changes in land-uses and fertilization are important factors regulating methane (CH) emissions from paddy soils. However, the responses of soil CH emissions to these factors and the underlying mechanisms remain unclear. The objective of this study was to explore the effects of land-use conversion from paddies to orchards and fertilization on soil CH fluxes, and the abundance and community compositions of methanogens and methanotrophs. Soil CH fluxes were quantified by static chamber and gas chromatography technology. Abundance and community structures of methanogens and methanotrophs (based on mcrA and pmoA genes, respectively) were determined by quantitative real-time PCR (qPCR), and terminal restriction fragment length polymorphism (TRFLP), cloning and sequence analysis, respectively. Results showed that land-use conversion from paddies to orchards dramatically decreased soil CH fluxes, whereas fertilization did not distinctly affect soil CH fluxes. Furthermore, abundance of methanogens and methanotrophs were decreased after converting paddies to orchards. Fertilization decreased the abundance of these microorganisms, but the values were not statistically significant. Moreover, land-use conversion had fatal effects on some members of the methanogenic archaea (Methanoregula and Methanosaeta), increased type II methanotrophs (Methylocystis and Methylosinus), and decreased type I methanotrophs (Methylobacter and Methylococcus). However, fertilization could only significantly affect type I methanotrophs in the orchard plots. In addition, CH fluxes from paddy soils were positively correlated with soil dissolved organic carbon contents and methanogens abundance, whereas CH fluxes in orchard plots were negatively related to methanotroph abundance. Therefore, our results suggested that land-use conversion from paddies to orchards could change the abundance and community compositions of methanogens and methanotrophs, and ultimately alter the soil CH fluxes. Overall, our study shed insight on the underlying mechanisms of how land-use conversion from paddies to orchards decreased CH emissions.
土地利用方式的改变和施肥是调节稻田土壤甲烷（CH）排放的重要因素。然而，土壤CH排放对这些因素的响应及其潜在机制仍不清楚。本研究的目的是探讨从稻田转变为果园的土地利用方式变化以及施肥对土壤CH通量、产甲烷菌和甲烷氧化菌的丰度及群落组成的影响。通过静态箱和气相色谱技术对土壤CH通量进行定量分析。分别采用定量实时PCR（qPCR）以及末端限制性片段长度多态性（TRFLP）、克隆和序列分析来测定产甲烷菌和甲烷氧化菌的丰度及群落结构（分别基于mcrA和pmoA基因）。结果表明，从稻田转变为果园的土地利用方式显著降低了土壤CH通量，而施肥对土壤CH通量没有明显影响。此外，稻田转变为果园后，产甲烷菌和甲烷氧化菌的丰度降低。施肥降低了这些微生物的丰度，但数值没有统计学意义。而且，土地利用方式的转变对产甲烷古菌的一些成员（甲烷微菌属和甲烷八叠球菌属）有致命影响，增加了Ⅱ型甲烷氧化菌（甲基孢囊菌属和甲基弯曲菌属），并减少了Ⅰ型甲烷氧化菌（甲基杆菌属和甲基球菌属）。然而，施肥仅能显著影响果园地块中的Ⅰ型甲烷氧化菌。此外，稻田土壤的CH通量与土壤溶解有机碳含量和产甲烷菌丰度呈正相关，而果园地块中的CH通量与甲烷氧化菌丰度呈负相关。因此，我们的结果表明，从稻田转变为果园的土地利用方式变化可改变产甲烷菌和甲烷氧化菌的丰度及群落组成，并最终改变土壤CH通量。总体而言，我们的研究揭示了从稻田转变为果园的土地利用方式变化降低CH排放的潜在机制。
