HUANG Kerui，LIU Fang，LI Zizun，LI Yuancheng
( Guangxi College and University Key Laboratory of Regional Ecological Environment Analysis and Pollution Control of West Guangxi, Baise University, Baise 533000,China)
Abstract: The two most widely distributed soils (lime soil and yellow soil) in the karst area of southwest Guangxi were selected as research objects in this study. The effects of the land use change, from abandonment to reforestation, on CH4 oxidation were studied on the basis of field inspection and laboratory soil CH4 oxidation kinetics test. The results revealed that the land use change affects the CH4 flux variously for different soils, e.g. CH4 fluxes in lime soils decreased following the order of abandoned land LS-3[-64.30 μg/(m2？h)]> natural bushes LS-1 [-48.96 μg/(m2？h)]> cultivated land LS-2 [29.61 μg/(m2？h)],while in yellow soils, the order was reforest YS-2[-36.95 μg/(m2？h]> cultivated land YS-1[-29.44 μg/(m2？h)]. The CH4 oxidation in soils followed the standard Michaelis-Menten kinetics, with CH4 Vmax values of 400 to 4347 pmol/(g？h) and Km values of 72~878.3 μL/L. The Vmax value measured in lime soils was more than twice of that in yellow soils, indicating the higher oxidation potential of lime soils. The tendency of seasonal CH4 flux changes was indistinct, however the release and absorption peaks were usually found in autumn or winter. Generally, the soil temperature had a positive effect on CH4 uptake. The soil moisture had a remarkable negative effect on CH4 fluxes in soils, LS-1 and LS-3, which experienced slight human disturbance, while the soil ammonium nitrogen content was the dominated factor for CH4 oxidation in soils, i.e. dry lands LS-2 and YS-1 and forest land YS-2. Our results suggested that the soil restoration has a positive effect on CH4 consumption, but its degree depends on not only the change of soil physical and chemical properties and methane microbial community but also regional climate factors.
Key words: karst; land use; methane
EARTH AND ENVIRONMENT Vol.46, No.6, Tot No.326, 2018, Page 534-541
