Insights into the Distribution of Soil Organic Carbon in the Maoershan Mountains, Guangxi Province, China: The Role of Environmental Factors

The forest ecosystem is the largest carbon reservoir in the terrestrial ecosystem, with soil organic carbon (SOC) being its most important component. How does the distribution of forest SOC distribution change under the influence of regional location, forest succession, human activities, and soil depth? It is the basis for understanding and evaluating the value of forest SOC reservoirs and improving the function of forest soil carbon sinks. In this paper, soil organic carbon concentrations (SOCCs) and environmental factors were measured by setting 14 experimental plots and 42 soil sampling sites in different forest communities and different elevations in the Maoershan Mountains. The redundancy analysis (RDA) method was used to study the relationship between SOC distribution and external factors. The results show that SOC distribution was sensitive to elevation, forest community, and soil layer. It had obvious surface aggregation characteristics and increased significantly with the increase in elevation. Among them, SOCCs increase by 1.80 g/kg with every 100 m increase in elevation, and that decreased by 5.43 g/kg with every 10 cm increase in soil depth. The SOC distribution in natural forests is greater than that in plantations, and the spatial variation in SOC distribution in plantations is higher due to the effect of cutting and utilization. SOC distribution is the result of many environmental factors. The response of SOC distribution to the forest community indicates that the development of plantations into natural forests will increase SOC, and excessive interference with forests will aggravate SOC emissions. Therefore, strengthening the protection of natural forests, restoring secondary forests, and implementing scientific and reasonable plantation management are important measures for improving the SOC reservoir’s function.