Annual methane uptake of an artificial grassland under different grazing strategies

Increased grazing has led to the degradation of natural grasslands, which can be mitigated by implementing artificial grasslands. Continuous and rotational grazing are the most important and widely used grazing management strategies. However, our understanding of how diverse grazing management strategies affect methane (CH 4 ) flux from artificial grasslands remains limited. Using a static opaque chamber and gas chromatography technique, methane fluxes and environmental factors from three grazing strategies (continuous grazing (CG), rotational grazing (RG), and ungrazed (UG)) were compared over a three-year period in an artificial grassland in a temperate semi-arid area in northern China. Our results showed that artificial grasslands are a net sink for atmospheric CH 4 . The sink strength was 2.0, 1.4, and 1.6 kg C ha −1 yr −1 for UG, CG, and RG, respectively. Grazing reduced CH 4 uptake by 28–42% for CG and 18–32% for RG, compared to UG. However, there was no significant difference in CH 4 uptake between CG and RG. CH 4 uptake during the non-growing season accounted for 32–34% of the annual CH 4 uptake, a significant proportion of the annual total. CH 4 uptake increased with soil temperature for CG, RG, and UG and was significantly correlated with water-filled pore space for CG and UG over the three-year period. Variations in soil ammonium and nitrate levels exhibited a slight influence on CH 4 flux for CG and RG. Our study provides long-term observations of grazing strategies affecting CH 4 uptake in grasslands, facilitating evaluation of the effects on grassland CH 4 uptake from rotational grazing and continuous grazing.