Effects of Grazing Intensity on Ecosystem Gas Exchange of Different Grassland Types in Inner Mongolia

In order to reveal the variation of gas exchange under different grazing intensities and grassland types in Inner Mongolia,gas exchange under different grazing intensities for three main grassland types(meadow steppe,typical steppe and desert steppe) were measured by using infrared analyzer(IRGA;LI-6400,Li-Cor,Lincoln,NE,USA) with a transparent chamber(0.5 m×0.5 m×0.5 m) in middle August.Results indicated that ecosystem net CO2 exchange(NEE),ecosystem respiration(ER) and gross ecosystem productivity(GEP) were significantly different between types(P0.05).NEE and GEP decreased and ER increased in meadow steppe with grazing intensities increasing.NEE and GEP increased and ER decreased in typical steppe with grazing intensities increasing;NEE and GEP increased and ER decreased in desert steppe with grazing intensities increasing compared to control.Grazing affected ecosystem gas exchange through influencing plants and soil of grassland ecosystem.