[Effects of Grazing Intensity on Greenhouse Gas Emissions in a Typical Grassland].

Abstract

The research investigating the effects of different grazing intensities on greenhouse gas emissions within typical steppe ecosystems aids in formulating effective management strategies for these ecosystems. Furthermore, it plays a vital role in developing approaches to reduce greenhouse gas emissions. To investigate the effects of different grazing intensities on greenhouse gas emissions in typical steppe ecosystems, four treatments were established： no grazing （CK）, light grazing （LG）, moderate grazing, and heavy grazing （HG）. The greenhouse gas emission fluxes were measured using the static dark chamber infrared spectroscopy method. The results showed that： ① Significant seasonal changes exist in ecosystem respiration and CH₄ emission flux. Compared with the CK treatment, the HG treatment significantly reduced the total ecosystem respiration emission by 31.43%, while the total CH₄ emission was not significant among all treatments. Compared with the LG treatment, the HG treatment significantly reduced the total N₂O emission by 94.03% （P <0.05）. ② A significant linear correlation exists between the values of ecosystem respiration pairs and soil temperature （P <0.001）, and there was a significant linear relationship between ecosystem respiration and soil water content under the CK and HG treatments （P <0.05）, mainly related to soil temperature. Except for the LG treatment, the CH₄ emission fluxes of the other treatments showed a quadratic correlation with soil temperature, and the CH₄ emission fluxes of all treatments were linearly correlated with soil water content and were mainly correlated with soil water content （P <0.01）. A significant linear correlation exists between N₂O emission flux and soil temperature in the LG treatment （P <0.05）. ③ Compared with that in CK, the HG treatment significantly decreased soil water content, soil total carbon, soil total nitrogen, vegetation aboveground biomass, and litter, and significantly increased soil temperature and soil bulk density （P <0.05）. Heavy grazing reduced the total greenhouse gas emissions and total vegetation biomass. Although it reduced the carbon emissions of the grassland ecosystem, it was not conducive to maintaining the ecological balance of grassland. This study can provide reference data and theoretical support for evaluating the effects of grazing on the source-sink functions of grassland ecosystems.