Environmental Benefit Evaluation Of Different Land Use Modes In Huoshaoping Township,hubei Province

Global climate change is one of the most concerned scientific issues at present.The increase in atmospheric greenhouse gas content is the main cause of global warming,and land use change has become an important source of soil greenhouse gas emissions.Huoshaoping Township,Changyang Tujia Autonomous County,Yichang,Hubei Province,altitude of 1,800 meters.For more than 30 years,due to the excessive use of chemical fertilizers,reclamation of wasteland,and planting of alpine vegetables,it has brought huge benefits,but also the environment has brought great damage,such as increased greenhouse gas emissions.Therefore,it is significance to discuss the characteristics of soil carbon and nitrogen fluxes and storage under different land use modes and their influencing factors for environmental benefit evaluation.In this study,three land use modes in Huoshaoping Township were cropland,artificial grassland and natural woodland.The plants and soil were collected for nutrient element determination,analysis of soil carbon and nitrogen storage,and use the static camera obscura method to observate and analyze soil greenhouse gas fluxes under different land use modes.The main conclusions are as follows:1.Compared with cropland,the construction of artificial grassland reduces soil atmospheric temperature and increases plant aboveground biomass,total carbon content of plant aboveground parts,soil organic carbon,total carbon and total nitrogen content,soil invertase,protease,catalase,microbial biomass carbon and microbial biomass nitrogen,the construction of artificial grassland increases soil carbon and nitrogen storage.2.During the observation period,the CO₂flux had obvious dynamic changes under the three land use modes.The CO₂flux in the growing period is emission,and the emission is from large to small:artificial grassland(151.0 mg·m^-2·h^-1)>natural woodland(82.8mg·m^-2·h^-1)>cropland(28.4 mg·m^-2·h^-1),and artificial grassland was significantly higher than cropland（p<0.05）.The CO₂emission flux was mainly affected by soil water content and soil catalase activity.3.During the observation period,the CH₄flux in artificial grassland increased significantly,and the natural woodland decreased significantly in the ablation period.CH₄fluxes in the growing period showed as emissions from cropland(31.3 ug·m^-2·h^-1),artificial grassland(-16.0 ug·m^-2·h^-1)and natural woodland(-11.9 ug·m^-2·h^-1)are all shown as absorption.The CH₄emission flux was mainly affected by soil temperature,water content and microbial biomass carbon.4.During the observation period,the variation trend of N₂O flux in cropland and natural woodland was similar.The N₂O fluxes of growing cropland(32.6 ug·m^-2·h^-1)and natural woodland(2.7 ug·m^-2·h^-1)showed emission,while artificial grassland showed weak absorption.The N₂O emission flux was mainly affected by soil temperature,water content and catalase.To sum up,different land use modes directly changed the community biomass,soil physicochemical properties and soil biological activity of the southern alpine ecosystem,which in turn affected the soil carbon and nitrogen fluxes and carbon and nitrogen storage in the southern alpine ecosystem.Artificial grassland soil carbon and nitrogen flux are higher,but because artificial grassland has higher aboveground biomass,high biomass leads to strong photosynthetic respiration,and the total amount of greenhouse gases emitted to the atmosphere is lower.Therefore,the construction of artificial grassland is conducive to reducing the emission of soil carbon and nitrogen,and increasing the storage of soil carbon and nitrogen in the study area.