Three years of CO, CH and NO fluxes from different sheepfolds in a semiarid steppe region, China.

To better assess greenhouse gas (GHG) emissions from livestock folds in semi-arid steppe zones and reduce uncertainties in regional and national GHG emission inventories, we measured the fluxes of carbon dioxide (CO), methane (CH) and nitrous oxide (NO) from sheepfolds under contrasting management regimes (i.e., summer sheepfolds under continuous and rotational grazing strategies and the winter sheepfold) for 3 consecutive years. Our results showed that these GHG fluxes had high intra-annual and interannual variations, emphasizing the importance of multi-year measurement for achieving temporally representative annual budgets. Sheep presence and temperature appeared to be the key factors driving CH, CO and NO fluxes from sheepfolds, e.g., higher GHG emissions usually occurred in seasons with sheep presence. However, the sheepfold type exerted a distinct influence on the temperature sensitivity of GHG fluxes, i.e., the Q values for GHG fluxes were generally higher in summer sheepfolds than in winter sheepfold. The annual CH, CO and NO emissions for the 3 sheepfolds were estimated to be 1.5-16.5 kg C ha yr (or 1.9-2.6 g C yrsheep), 8.6-16.0 t C ha yr (or 5.1-6.6 kg C yrsheep) and 28.3-41.9 kg N ha yr (or 19.0-26.8 g N yrsheep), respectively. Averaging across the 3 years, the annual net GHG emissions (CH + CO + NO) for all sheepfolds ranged from 47 to 71 t CO-eq ha yr (or 27-36 kg CO-eq yr sheep), of which CO and NO emissions contributed the most; moreover, the annual net GHG emissions had no significant differences between sheepfold types or grazing strategies. Given that local steppe soils have a lower magnitude of soil respiration (CO) and NO emissions and are also net sink for atmospheric CH, the sheepfold sites in this region are undoubtedly one of the significant hotspots for GHG emissions and could be key areas to focus mitigation action.