Abstract:

Global climate change is closely related to the carbon cycle, and exploring changes in surface carbon emissions is an essential aspect of climate change research. In this study, the CO₂ fluxes of surface soils in Qingliangsigou watershed of Loess Hills and Gullies in northwest Shanxi were measured using an LI-8100A soil carbon flux automatic measurement system, the soil particle size was measured using a laser particle size analyzer (mastersizer 2000), the soil organic matter was measured using a chemical titration method, and the soil water content was measured using the drying method. Additionally, we explored the diurnal and spatial variation of surface soil CO₂ fluxes, temporal and spatial changes, CO₂ fluxes under different land use types, and the influence of environmental factors on surface soil CO₂ fluxes to complement the study of surface soil CO₂ fluxes in small watershed areas in the Loess Hills and Gullies of northwest Shanxi. We found that CO₂ fluxes showed a single peak in variation during the growing season, reaching a single day minimum around sunrise and a single day maximum between 16:00 and 22:00, and in the non-growing season, there was irregular variation. The CO₂ fluxes of farmland were lower than the CO₂ fluxes of waste grassland and jujube forest land. The highest CO₂ fluxes were observed in August, followed by May, and the lowest CO₂ flux was in November. The CO₂ flux of surface soil was closely related to photosynthetic effective radiation, atmospheric temperature, soil temperature, soil water content, soil organic matter, and soil texture. Therefore, the carbon fixation of soil can be effectively improved through scientific land use. In conclusion, the results of this study can be applied to most of the Loess Plateau and used to improve the ecological environment.

Key words: soil CO₂ flux, spatial and temporal variation characteristics, influencing factors, land use type, loess hilly gully area, northwest Shanxi