干旱区生态环境知识资源中心

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 (CO(2)), methane (CH(4)) and nitrous oxide (N(2)O) 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 CO(2), CH(4) and N(2)O. Temperatures primarily determined the seasonal pattern of CO(2) emission; 60-84% of the CO(2) flux variation could be explained by temperature changes. High rates of net CH(4) 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 N(2)O emissions were also be related to rainfall and spring-thaw events. The total annual cumulative GHG emissions in CO2 equivalents (CO2: 1; CH(4):25; and N(2)O: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, CH(4) release accounted for approximately 1% of emissions, while CO(2) and N(2)O emissions contributed to approximately 59% and 40%, respectively. The total GHG emission factor (CO(2)+CH(4)+N(2)O) per animal for the sheepfolds investigated in this study was 30.3 kg CO(2) eq yr(-1) head(-1), which translates to 0.3, 18.8 and 11.2 kg CO(2) eq yr(-1) head(-1) for CH(4), CO(2) and N(2)O, respectively. Sheepfolds accounted for approximately 34% of overall N(2)O emissions in the Baiyinxile administrative region, a typical steppe region within Inner Mongolia. The contribution of sheepfolds to the regional CO(2) or CH(4) exchange is marginal.