Effect of 5 years long cessation of grazing on methane uptake in a semi-arid grassland

Grazing exerts a key role in nutrient cycling in grassland ecosystems, however, little is known about the effects of short-term enclosure on methane (CH₄) fluxes in a semi-arid steppe biome like this of Inner Mongolia. CH₄ fluxes were measured in the Leymus chinensis (Trin) Tzvel. grassland using static chamber and gas chromatography (GC). Measurements were carried out twice per month over a growing season in 2004 at the two sites (one fenced since 1999 (UG99) and the other subjected to freely grazing (FG)). All CH₄ fluxes were positive, indicating that this grassland functioned as the active atmospheric CH₄ uptakes. During this period, the UG99 site (57.6 ± 6.7 μg C m^-2 h^-1) had significantly higher mean CH₄ uptake in comparison to the FG site (37.0 ± 6.3 μg C m^-2 h^-1). A significant liner negative correlations between CH₄ uptake and soil moisture (0-5 cm) at the both sites were found (P <0.05). The results indicated that short-term enclosure was helpful to improve CH₄ uptake in this area.