黄土高原不同土地利用方式对土壤N2O通量的影响 postprint

Abstract: Nitrous oxide (N2O) a remarkable greenhouse gas in the atmosphere, exerts a pronounced effect on global climate warming. Changes in land use types critically affects N2O emissions, particularly in ecologically fragile semiarid regions with more complex underlying mechanisms. However, there is still a lack of systematic research on how complex and diverse land use types affect soil N2O emissions in semiarid regions of China and the key driving factors involved. To address this, this study focused on four typical land use types in the semiarid Loess Plateau of central Gansu Province: Picea asperata forest (Piceaasperata); Medicago sativa grassland (Medicago sativa); abandoned land (Abandoned land); and wheat field (Wheat field). Soil N2O fluxes were monitored using the static chamber-gas chromatography method, combined with soil physicochemical property data,to elucidate the key drivers regulating soil N2O emissions under different land use types. Compared to the abandoned land, the Picea asperata forest and Medicago sativa grassland had significantly increased soil water content, while wheat fields exhibited elevated ammonium nitrogen (NH4+-N) and nitrate nitrogen (NO3−-N) concentrations. Compared to the abandoned land, the Medicago sativa grassland and wheat fields exhibited markedly enhanced nitrate reductase and nitrite reductase activities, which decreased with an increase in soil depth across all treatments. Soil N2O fluxes under different land use types exhibited an initial increase followed by a decline during the vegetation growth stages. The total soil N2O emissions decreased by 34.2% and 23.3% in the Picea asperata forest and Medicago sativa grassland, respectively, and increased by 32.47% in the wheat fields, compared to the abandoned land. Random forest analysis identified soil temperature as the most influential factor affecting the soil N2O flux. Overall, compared to the abandoned land and wheat fields, the artificial forest and grassland systems in the study area demonstr