Annual emissions of greenhouse gases from sheepfolds in Inner Mongolia
Sheepfolds represent significant hot spot sources of greenhouse gases (GHG) in semi-arid grassland regions, such as Inner Mongolia in China. However, the annual contribution of sheepfolds to regional GHG emissions is still unknown. In order to quantify its annual contribution, we conducted measurements of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) fluxes at two sheepfold sites in the Baiyinxile administrative region of Inner Mongolia for 1 year, using static opaque chamber and gas chromatography methods. Our data show that, at an annual scale, both sheepfolds functioned as net sources of CO2, CH4 and N2O. Temperatures primarily determined the seasonal pattern of CO2 emission; 60–84% of the CO2 flux variation could be explained by temperature changes. High rates of net CH4 emissions from sheepfold soils were only observed when animals (sheep and goats) were present. While nitrous oxide emissions were also stimulated by the presence of animals, pulses of N2O emissions were also be related to rainfall and spring-thaw events. The total annual cumulative GHG emissions in CO2 equivalents (CO2: 1; CH4: 25; and N2O: 298) were quantified as 87.4 ± 18.4 t ha−1 for the sheepfold that was used during the non-grazing period (i.e., winter sheepfold) and 136.7 ± 15.9 t ha−1 used during the grazing period (i.e., summer sheepfold). Of the annual total GHG emissions, CH4 release accounted for approximately 1% of emissions, while CO2 and N2O emissions contributed to approximately 59% and 40%, respectively. The total GHG emission factor (CO2 + CH4 + N2O) per animal for the sheepfolds investigated in this study was 30.3 kg CO2 eq yr−1 head−1, which translates to 0.3, 18.8 and 11.2 kg CO2 eq yr−1 head−1 for CH4, CO2 and N2O, respectively. Sheepfolds accounted for approximately 34% of overall N2O emissions in the Baiyinxile administrative region, a typical steppe region within Inner Mongolia. The contribution of sheepfolds to the regional CO2 or CH4 exchange is marginal.
KeywordsCarbon dioxide Methane Nitrous oxide Sheepfold Semi-arid grassland Xilin River catchment
This work was supported by the National Natural Science Foundation of China (40805061, 40425010) and the German Research Foundation (DFG, Research Unit No. 536, “Matter Fluxes in grasslands of Inner Mongolia as influenced by stocking rate”, MAGIM). Further support was provided by the Helmholtz-CSC stipend program and the Helmholtz-funded joint laboratory ENTRANCE of IMK-IFU and IAP-CAS. Thanks are also due to IMGRS of CERN and the staffs from IAP, IB and IMK-IFU for their help in field experiments.
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