Impacts of no grazing in summer on greenhouse gas emissions from Kobresia humilis alpine meadow

Using close chamber-GC method, the impacts of no grazing in summer on greenhouse gas emissions from Kobresia humilis alpine meadow, soil properties, and biomass were measured in 2004. The results indicated that vegetation coverage was increased by 41%, biomass increased by 53% per hectare and soil properties changed significantly after eight years in no grazing grassland when compared to grazing grassland. CO₂ respiration from vegetation and soil of no grazing grassland was 20.7% lower than that from grazing grassland. The average emission rates were 30.7 kg·(hm²·d)^-1 for no grazing grassland and 38.7 kg·(hm²·d)^-1 for grazing grassland. Both Kobresia humilis alpine meadow with grazing and no grazing activities showed to be a sink of atmospheric CH₄ and the uptake rate of CH₄ was enhanced after the prohibition of grazing. The average uptake rates of CH₄ for no grazing grassland were 28.1 gCH₄·hm^-2·d^-1 and 21.9 gCH₄·hm^-2·d^-1 for grazing grassland. N₂O emission was lower from no grazing grassland than that from grazing grassland. The average emission rates of N₂O were 4.5 gN₂O-N·hm^-2·d^-1 and 7.6 gN₂O-N·hm^-2·d^-1 for no grazing grassland and grazing grassland, respectively. No grazing in summer weakened the contribution of grassland to the concentration of greenhouse gases in atmosphere compared to grazing grassland.