The degraded areas in Southern Brazil are undergoing rapid conversion from abandoned fields into agroforestry system. Our focus was to investigate the impact of land use and soil properties on soil fauna and quality in an agroforestry system and a natural ecosystem. The agroforestry system had the presence of Cicadidae (0.1 ind trap−1), Diplura (0.01 ind trap−1), Gryllidae (0.2 ind trap−1), Gyrinidae (0.07 ind trap−1), and Larvae (0.3 ind trap−1), and it presents lower SOC (less 44.3%) and higher total N (more 29.8%) and P contents (more 68.8%) when compared with the natural ecosystem. Richness and diversity declined (less than 16.3 and 31.8%, respectively) with increasing soil pH. Natural ecosystem showed the greatest diversity (H' = 2.44) of soil fauna. A negative correlation was observed between diversity and soil pH (−0.91), and positive correlations among diversity and SOC (0.97), richness (0.88), and dominance (0.93). In conclusion, fauna abundance, precipitation, and soil pH played essential roles in soil quality through ecosystem services, habitat, and energy provision, which in turn promoted the entire soil food web. Thus, the findings in the agroforestry system and natural ecosystem help us to understand how land uses impact soil fauna, and soil quality. [ABSTRACT FROM AUTHOR]