Soil Physicochemical and biochemical Differentiation Under Dominant Broadleaf Forest Species in the Eastern Black Sea Region

Soil physicochemical and biochemical properties are fundamental to soil processes and ecosystem functioning in forested landscapes. However, their responses to dominant tree species in humid montane regions remain unclear. This study examined how three widespread broadleaf species—Quercus pontica, Quercus petraea, and Fagus orientalis—influence the physical, chemical, and biochemical properties of the soil in natural forests in the Eastern Black Sea region. Fifteen soil samples (five from each forest type) were collected under comparable climatic and geological conditions and analyzed for texture, pH, electrical conductivity, organic carbon content, and key biochemical indicators of microbial activity. Significant differences in soil properties were observed among forest types. Soils beneath Q. pontica exhibited a lower pH level (3.26), a higher organic carbon content (3.82), microbial abundance, and enhanced biochemical activity. enhanced biochemical activity. In contrast, Pontic oak-dominated stands were characterized by distinct textural and chemical signatures. Multivariate analyses revealed that soil texture fractions, pH, and microbial carbon acted as the primary edaphic filters driving differentiation of soils among forest types. These patterns suggest that species-specific litter inputs and belowground processes regulate soil biochemical functioning by modifying resource availability and physical habitat conditions. Our results demonstrate that, even under similar environmental conditions, dominant tree species exert a strong influence over soil physicochemical and biochemical properties. Understanding these species-specific soil responses is essential for predicting ecosystem functioning, carbon cycling, and sustainable forest management in a changing environment.