Three years of CO 2 , CH 4 and N 2 O 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 (N O) 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 N O 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 N O emissions for the 3 sheepfolds were estimated to be 1.5-16.5 kg C ha yr (or 1.9-2.6 g C yr sheep ), 8.6-16.0 t C ha yr (or 5.1-6.6 kg C yr sheep ) and 28.3-41.9 kg N ha yr (or 19.0-26.8 g N yr sheep ), respectively. Averaging across the 3 years, the annual net GHG emissions (CH + CO + N O) 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 N O 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 N O 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.