Natural forests tend to be converted into agricultural lands in developing countries for economic development. In the subtropical regions of China, natural secondary forests are generally converted to banana, rubber, and eucalyptus plantations. Unlike natural forests, agricultural lands are mainly characterized by mono鄄plantations, tillage, fertilization, and litter removal. These practices may have unfavorable consequences on the soil ecosystem. Moreover, the soil in the subtropical regions of China is classi覱ed as Ultisol, which is vulnerable to erosion and degradation under improper soil management. Yet, knowledge about the effects of the conversion of natural forests to agricultural lands on soil quality in these regions remains scarce. Soil microorganisms are critical for organic matter conversion and nutrient cycling, in addition to being sensitive to environmental changes. Thus, soil microbial parameters such as microbial biomass, activity, biodiversity, and composition are considered as reliable indicators of soil quality. To understand the effect of forest