[Greenhouse gases emission or uptake in Inner Mongolia natural and free-grazing grasslands].

GC-MS was used to measure the greenhouse emission of Inner Mongolia Grassland. The results showed that four kinds of typical semi-arid grasslands in Inner Mongolia had their own special seasonal patterns as the source of atmospheric N2O and CO2 emission and the sink of atmopsheric CH4, which were controlled by seasonal weather variation. Different soil and vegetation types and precipitation influenced the intensity of emission and upatake of the gases. Compared with natural grassland, free grazing decreased CH4 uptake and N2O emission, but increased CO2 emission.