10:45 〜 12:15
[BBC02-P05] Spatial patterns of soil CH4 flux in a mountain forested watershed: topographic and biogeochemical controls
キーワード：Upland forest, greenhouse gas, soil, landscape, watershed, Methane flux
Mountain forests are an integral component of the global carbon cycle, playing a key role in the exchange of greenhouse gases. Methane (CH4) is a potent greenhouse gas. Upland soils are thought to be sinks of atmospheric CH4, but soils in riparian zones of mountain streams can potentially act as sources of CH4, which is usually overlooked in global CH4 budget. Thus, understanding how the landscape structure influences the direction and magnitude of CH4 fluxes in mountain forested areas is important for accurately estimating CH4 budget at the watershed scale.
The study site is located in the upper watershed of the Yura River in the Ashiu Experimental Forest of Kyoto University. We installed 60 soil collars at a depth of 5 cm in the soil across the landscape, with a distance of about 30 m between each. With different transects we covered the ridge, hillslope, riparian zone and wetland as part of examining the influence of topography on CH4 fluxes. CH4 flux was measured using cavity an enhanced absorption spectroscopy gas analyser.
We mainly observed negative net CH4 fluxes, which means that overall the riparian zone, hillslopes and ridges were CH4 sinks. Soil CH4 uptake was highest mid-slope and lowest in the riparian zone and on ridges. Hotspots of CH4 emissions were found in wetlands.
A comprehensive understanding of the relationship between CH4 flux and landscape structure, as well as the associated controlling factors at different time scales, is necessary for the scaling up of chamber measurements of CH4 flux and the accurate determination of CH4 budgets in forested watershed ecosystems.
The study site is located in the upper watershed of the Yura River in the Ashiu Experimental Forest of Kyoto University. We installed 60 soil collars at a depth of 5 cm in the soil across the landscape, with a distance of about 30 m between each. With different transects we covered the ridge, hillslope, riparian zone and wetland as part of examining the influence of topography on CH4 fluxes. CH4 flux was measured using cavity an enhanced absorption spectroscopy gas analyser.
We mainly observed negative net CH4 fluxes, which means that overall the riparian zone, hillslopes and ridges were CH4 sinks. Soil CH4 uptake was highest mid-slope and lowest in the riparian zone and on ridges. Hotspots of CH4 emissions were found in wetlands.
A comprehensive understanding of the relationship between CH4 flux and landscape structure, as well as the associated controlling factors at different time scales, is necessary for the scaling up of chamber measurements of CH4 flux and the accurate determination of CH4 budgets in forested watershed ecosystems.