Soil carbon dioxide dynamics in deep profiles under erosional and depositional conditions on the Chinese Loess Plateau
Description
Soil erosion, a major process in soil degradation, significantly influences carbon emissions and the CO₂ exchange between the atmosphere and soil, affecting the redistribution of soil organic carbon (SOC) and soil inorganic carbon (SIC). This, in turn, has important implications for the global carbon cycle and climate change. Understanding soil carbon dynamics under different erosion and deposition conditions is essential for managing carbon stocks. This study investigates the effects of erosion and deposition on SOC and SIC distribution and their contribution to CO₂ flux across soil profiles (0-200 cm depth) at three check dams in the Loess Plateau, China. The results show that soil erosion reduces carbon stocks, with SOC decreasing by 13.0% and SIC by 2.1% at depositional sites compared to erosional sites. CO₂ fluxes at erosional sites are significantly lower than at depositional sites, with fluxes peaking in August during the growing season. Seasonal variations in CO₂ flux are consistent across erosion environments. Correlation analysis indicates that at erosional sites, CO₂ flux is strongly correlated with soil temperature, SOC, SIC, and pH, while at depositional sites, it is more strongly correlated with soil temperature and moisture content. These findings highlight differing environmental controls on CO₂ flux between erosion and deposition sites. Additionally, δ¹³C values of CO₂ emissions were more negative at erosion sites, reflecting a higher contribution from SOC, while at deposition sites, the values were less negative, indicating a stronger influence of SIC, especially in deeper soil layers. The study emphasizes that SOC and SIC play crucial roles in influencing soil CO₂ flux, with the dynamics of carbon redistribution under erosion processes significantly affecting carbon cycling and storage. These results underline the need for site-specific land management strategies to mitigate soil carbon loss and enhance soil health in erosion-prone areas.