Methane Uptakes and Emissions in Upland Tropical Forest and Agricultural Soils

Journal article

Authors/Editors

Strategic Research Themes

No matching items found.

Publication Details

Author list: Vanitchung, S.;Chidthaisong, A.;Conrad, R.

Publication year: 2014

Journal: Journal of Sustainable Energy and Environment (1906-4918)

Volume number: 5

Issue number: 2

Start page: 43

End page: 49

ISSN: 1906-4918

Abstract

Three land use types in Thailand; 1) the natural forests (hill evergreen forest (HEF), dry evergreen forest (DEF), moist evergreen forest (MEF) and mixed deciduous forest (MDF)), 2) a reforested forest (ARF) and 3) agricultural field (AG) were studied for their methane fluxes, oxidation potential and kinetics. Net atmospheric methane consumption was observed at all forest and reforested sites, with the montly consumption rate raning from -0.6 mg CH4 m-2 day-1 at the reforested site to 2.4 mg CH4 m-2 day-1 at the hill evergreen forest site. At the agricultural site the net methane emission of 13.6 mg CH4 m-2 day-1 was found. At dry evergreen forest and reforested sites, a clear zonation for active methane oxidation layer was detected along the soil depths. The most active oxidation lied between 15 cm and 40 cm while in agricultural soil no clear active layer was observed. Stratification of active oxidation zones coincided with the trends of inorganic nitrogen content profile. In DEF and ARF soils, high concentration of inorganic nitrogen compounds (usually > 100 mg NO3- or NH4+ ⋅ kg soil-1 ) was detected in the top 15-cm soil while there was no clear distribution trend found in AG soil. Examining kinetic coefficients of these active layers revealed that soil at all natural forest sites had high affinity for methane (Km of 52 ppmv) but rather low methanotrophic capacity (Vmax of 0.82 nmol⋅g soil-1 ⋅ h-1 ). Soil at ARF and AG sites, on the other hand, showed low affinity for methane (Km of 724 ppmv and 1454-2362 ppmv, respectively). However, soils at these two sites were capable of oxidizing high concentration of methane (Vmax about 10 nmol ⋅ g soil-1 ⋅ hr-1 ). These results indicate that land use type significantly affects rates, depth distribution and kinetics of methane oxidation in tropical soils.

Keywords

Methane oxidation, depth distribution, methane oxidation kinetics, and land use