Abstract: The rate of soil organic carbon (SOC) mineralization affects carbon dioxide (CO₂) concentration in the atmosphere, with consequences on global climate change. However, the effects of lithology on SOC mineralization remain undefined. A laboratory experiment was conducted to explore the lithology effects on SOC mineralization of soils that were developed from limestone in karstic areas and clastic rocks in non-karstic areas. Soil microbial activity, microbial biomass and community composition were determined by fluorescence analysis and phospholipid fatty acid (PLFA) method, respectively. Mineral factors, such as iron, aluminum oxides, and exchangeable calcium and magnesium contents, were used to estimate mineral conservation characteristics. There were significant differences in SOC mineralization between two soil types, as evidenced by a 38.5% higher cumulative mineralization of clastic rocks developed soils than that of limestone developed soils at the end of incubation (day 42). Soil physicochemical properties, microbial and mineral protective properties jointly explained 47.1% variations of SOC mineralization based on the variation partitioning analysis. The results of structural equation modeling further showed that lithology not only directly influenced SOC mineralization, but also indirectly influenced it by regulating soil mineral protection properties or soil chemical properties, or by regulating soil chemical properties and microbial properties. To predict soil carbon dynamics and minimize carbon emissions under global change, the importance of the lithological effects on SOC mineralization should be considered.

Key words: lithology, SOC mineralization, phospholipid fatty acid, soil enzymatic activity, mineral protection