[MIS25-10] Contribution of vegetation to methane emission produced in the soil of an upland forest: a 13CH4-labelling approach
キーワード：methane, forest soil, vegetation
The role of vegetation on net methane fluxes from upland forest ecosystem has only recently been underlined and is still not fully understand and quantify. Vegetation can be a net methane producer or emitter in some cases. In other cases, it can enhance the methane consumption by the forest soil. In upland forests, a decrease of the net methane uptake by 0 to 60% has been reported, but in a few cases, a doubling of consumption has been observed. One of the main sources of methane related to the vegetation is the transport of methane from deep anoxic soil layers where the methane is produced to the atmosphere through plant stems.
In order to quantify if vegetation is a preferential way of methane emission in our field site, a 13CH4 labelling had been undertaken. A pulse of 13CH4 was injected in the soil at a depth of 40 cm and 13CH4 was traced for two days after the pulse labelling in upper soil layers (0,5, 10, 25 cm depth), on the soil surface with soil chambers including or not herbaceous vegetation and in tree stem chambers.
Labelled CH4 was recovered in all compartments even if the forest was a net methane sink during this period. However, the vegetation (tree stems and understorey vegetation) have a limited contribution to the total recovery of labelled CH4 at the forest level, which is dominated by soil emission. Our results also confirm that a large part of the methane that diffuse from the deep soil layers is consumed before reaching the soil surface.
In order to quantify if vegetation is a preferential way of methane emission in our field site, a 13CH4 labelling had been undertaken. A pulse of 13CH4 was injected in the soil at a depth of 40 cm and 13CH4 was traced for two days after the pulse labelling in upper soil layers (0,5, 10, 25 cm depth), on the soil surface with soil chambers including or not herbaceous vegetation and in tree stem chambers.
Labelled CH4 was recovered in all compartments even if the forest was a net methane sink during this period. However, the vegetation (tree stems and understorey vegetation) have a limited contribution to the total recovery of labelled CH4 at the forest level, which is dominated by soil emission. Our results also confirm that a large part of the methane that diffuse from the deep soil layers is consumed before reaching the soil surface.