Comparative Analysis of Soil Organic Carbon and Soil Oxide Minerals across Different Climates and Forest Types

Soil organic carbon (SOC) is an important carbon stock and nutrient source. Most studies on SOC are related to climate conditions, vegetation, topography and land use, while the correlation between soil oxide minerals and SOC is still not extensively researched. Exploring the relationship between soil oxide minerals and SOC can enhance our understanding of the factors influencing SOC stocks and dynamics. We analyzed forest SOC content, employing correlation analysis to explore the relation ships between SOC content and soil pH, as well as soil oxide minerals. The study utilized data from natural and planted forests in two provinces in China with distinct climates, Heilongjiang (cold and dry climate) and Anhui (warm and humid climate). In both climates, natural forests exhibited higher SOC content compared to planted forests. The difference in SOC content between natural forests and planted forests was particularly pronounced in the surface soil under cold and dry climate. In com parison to forests in warm and humid climate, forests in cold and dry climate demon strated significantly higher levels of SOC. Soils in different climates had varying levels of oxidized mineral content. In soils of cold and dry climate, the levels of Na2O, MgO, CaO and MnO were higher, while soils in warm and humid climate had higher levels of SiO2 , Al2O3 , Fe2O3 , TiO2 and K2O. Si-2 exhibited a close correlation with other oxide minerals in the topsoil, whereas Fe2O3 and Na2O showed a strong correlation with other oxides in the subsoil. Under different climatic conditions, the same soil oxide mineral showed different correlations with SOC content. The contents of Al2O3 , Fe2O3 and Na2O were significantly and positively correlated with SOC contents in cold and dry climate, but significantly and negatively correlated in warm and humid climate. SOC and soil oxide minerals showed different characteristics under different climatic conditions and forest types. Additionally, soil oxide minerals and SOC exhibited a more significant correlation in the subsoil.