To investigate the effects of different forest covers and soil depth on selected physical, chemical, and biological soil properties, the present study was conducted in three forest stands: natural forest, poplar plantation, and alder plantation. A factorial experiment was carried out based on a randomized complete block design with three replications. In each land cover type, soil sampling was performed separately from the 0–20, 20–40, and 40–60 cm depths. The results showed that the effects of forest cover type and soil depth on all physical, chemical, and biological soil properties were significant at the 1% probability level (P ≤ 0.01). According to the findings, the poplar plantation, which consists of broadleaf species, had higher soil organic carbon (SOC) content than the other two land cover types. At the 0–20 cm depth, SOC content in the poplar stand was 13.61% and 6.55% higher than that of the natural forest and alder plantation, respectively. Following the strong positive correlation between SOC and several soil quality indicators, traits such as porosity (12.02% and 7.14%), total nitrogen (13.62% and 6.5%), cation exchange capacity (18.25% and 20.34%), total glomalin (8.75% and 4.96%), soil respiration (0.85% and 2.08%), and microbial biomass carbon (20.93% and 16.2%) also showed the highest values at the 0–20 cm depth of the poplar plantation compared with the other two stands. In addition, the lowest values of metabolic quotient, bulk density, and dispersible clay were observed in the surface layer of this stand. It is noteworthy that increasing soil depth was associated with a decrease in SOC and those properties positively correlated with it, whereas properties negatively correlated with SOC increased with depth. These findings indicate that forest cover type and, consequently, the quality of organic inputs, play a decisive role in determining soil quality.