Effects Of Simulated Fire And Warming On Soil Properties And Greenhouse Gas Flux Of Leymus Chinensis Grassland

Fire burning and climate warming have important effects on the soil-plant-atmosphere carbon and nitrogen cycle in grassland ecosystems.These two kinds of human disturbances have little research on the soil-plant-greenhouse gas in grassland.In this study,under the simulated fire and climate warming scenarios?small temperature increase T1 and large temperature increase T2?,we analyzed the soil properties of Leymus chinensis grassland,biomass below and above ground and the fluxes of greenhouse gases CO₂,CH₄and N₂O,To clarify the relationship between CO₂,CH₄and N₂O gas flux and soil indicators and biomass,provide a scientific basis for the correct management of grassland.The result shows:1. The burning changed the physical and chemical properties of the top soil in the Leymus chinensis grassland ecosystem.It increased the soil temperature,p H value and the content of available nitrogen in the soil;it reduced the soil water content,organic carbon,available potassium,microbial carbon,Microbial nitrogen and microbial biomass phosphorus content;the effects on soil total phosphorus,total potassium,and available phosphorus content were not significant.2. The CO₂and CH₄emission flux increased significantly after the fire burning,but the CO₂and CH₄emission flux returned to the normal level after 65 days and 50 days,respectively;Fire burning had no significant effect on N₂O emission flux.3. T1 and T2 treatments increased the soil temperature of 0—20 cm by 1.48? and2.91?,respectively;decreased the soil water content of 0—20 cm by 4.41%and 7.98%,respectively.At the same time,the warming treatments increased the underground biomass by 17.68%and 28.35%,increased above-ground biomass by 15.68%and 23.53%,respectively.The warming process reduced the soil organic carbon,total nitrogen,available nitrogen,available phosphorus,total phosphorus,total potassium,and microbial biomass phosphorus,but increased the soil available potassium,microorganisms carbon and microbial biomass nitrogen.4. T1 and T2 treatments significantly increased CO₂emissions and increased CH₄emissions but did not reach a significant difference.The warming treatments had no significant effect on N₂O.5. Air temperature,soil temperature,and soil moisture content could significantly explain the changes of CO₂,CH₄and N₂O emission fluxes.Among the soil physical and chemical indicators,the organic carbon,nitrate nitrogen content,and soil microbial biomass carbon-nitrogen ratio were the main factors which affected CO₂emissions.Meanwhile,microbial biomass carbon and soil microbial biomass carbon-to-nitrogen ratio were the main factors which affected CH₄emissions;organic carbon,available nitrogen and microbial biomass nitrogen contents had the best correlation with N₂O emissions.