Winter-Grazing Reduces Methane Uptake by Soils of a Typical Semi-Arid Steppe in Inner Mongolia, China

Using a fully automated chamber-based measuring system, continuous high-frequency measurements of methane (CH sub(4)) uptake by soil of a typical semi-arid steppe in Inner Mongolia were conducted. Two management regimes were investigated: ungrazed since 1999 (UG99) and winter-grazed since 2001 (WG01). The magnitude of CH sub(4) uptake at the ungrazed site was slightly higher compared with those of semi-arid grasslands in the USA, and much higher than at humid grasslands. The daily mean CH sub(4) uptake under both regimes showed a clear seasonal variability, which was mainly driven by soil temperature. The results suggested that grazing exerted a considerable negative impact on CH sub(4) uptake in semi-arid steppes at regional scales.