Spatial Variability of CO2, CH4, and N2O Fluxes during Midsummer in the Steppe of Northern China
Jianzhong Cheng1, Xinqing Lee1, Benny K.G. Theng2, Bin Fang1,3, Fang Yang1,3, Bing Wang1, Like Zhang1,3
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1State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences,
Guiyang 550002, PR China
2Landcare Research Private Bag 11052, Palmerston North 4442, New Zealand
3Graduate University of Chinese Academy of Sciences, 100049, Beijing, PR China
Pol. J. Environ. Stud. 2014;23(2):319–328
Spatial variability is a major source of uncertainty in estimating the fluxes of greenhouse gases between steppe and atmosphere. The fluxes of CO2, CH4, and N2O were carried out between 08:00 and 10:00 h. of the following day during the midsummer period from a transect (area: 5.25×106 ha) in the semiarid steppe of northern China, using the dark static chamber technique and gas chromatography. Two land uses were chosen for this study: soils with plant covers and bare soils. Daily average GHG fluxes from the steppe transect were: 1.3×105 t C for CO2, -66.3 t C for CH4, and 1.1 t N for N2O. The emission of CO2 from soils with plant cover was significantly higher (P < 0.05) than that from the corresponding bare soils. The canopy effect, however, was observed for neither CH4 (P = 0.058) nor N2O (P = 0.772). Air temperature and relative humidity were the major factors affecting the diurnal variation in site-based CO2 flux (P < 0.05), while soil pH controlled its spatial variation (P < 0.05). The spatial uptake of CH4 correlated negatively with soil total N (TN) content (P < 0.05), while the flux of N2O significantly increased with soil organic carbon (P = 0.031) and TN (P = 0.022), indicating that soil organic matter is an important factor determining the N2O flux in the steppe of northern China.