Driving mechanism of spatial differentiation patterns of CO2 flux on eroded slope in loess hilly region
HAO Wang-lin1,2,3, XIA Bin1,2, XU Ming-xiang1,2,4
1. Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling 712100, China; 2. University of Chinese Academy of Sciences, Beijing 100190, China; 3. Department of Life Sciences, LüLiang University, Lüliang 033000, China; 4. Institute of Soil and Water Conservation, Northwest A&F University, Yangling 712100, China
Abstract:On eroded slopes with different soil organic carbon (SOC) levels in loess hilly region, the spatial differentiation patterns driving factors and process mechanisms of CO2 fluxes were analyzed, and a subsection model of CO2 fluxes was constructed. The results showed that: (1) The spatial differentiation patterns of soil CO2 flux on slopes caused by erosion was as follows: sedimentary area (S) > control area (CK) > eroded area (E); the increase of SOC level can promote the increase of CO2 flux in all parts of slope. (2) The erosion reduced soil moisture, bulk density and aggregate stability, cause soil nutrient loss, reduce bacteria diversity and fungal diversity; sedimentation caused the opposite phenomenon. The effect of erosion/sedimentation process on soil temperature was not significant. The increase of SOC level can effectively improve soil particles, soil moisture, increase bulk density, inhibit soil nutrient loss, increase bacteria diversity but reduce fungal diversity. (3) Our structural equation model analyzed the multi-factor driving mechanism of erosion location, soil temperature, soil moisture, SOC, DOC, SMBC, fungal diversity and bacterial diversity on CO2 flux (R2=77%). Our model also identified soil temperature, soil moisture and SMBC as the direct influencing factors of CO2 flux. Based on the two-factors hydrothermal model, the T&M&C model was built by embedding the C factor which could indirectly represent the microbial activity and available carbon substrate, thus allowing to estimate more accurately the CO2 flux in different parts of the erosion slope (R2>67%).
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