The microclimate created by tree canopies plays an important role in influencing various components of semi-arid ecosystems. Soil mesofauna are vital members of these ecosystems and is essential to understand their biodiversity and the factors that influence them. Mesofauna and soil samples were collected from soil depths (0–5 and 5–15 cm), both under the canopy and in outdoor spaces. Results indicate that mesofauna biodiversity was significantly higher in the surface soil layer beneath the canopy. Among the soil physicochemical properties, organic matter, total nitrogen, and available phosphorus were identified as the main drivers of mesofauna biodiversity. Overall, the findings highlight the essesial role of oak-induced microclimatic conditions in shaping soil mesofaunal diversity. During spring, soil moisture levels increased and the microclimatic buffering effect of the herbaceous layer moderated temperature fluctuations and reduced evaporative losses, thus creating favorable conditions for mesofauna activity and diversity in outdoor areas. In contrast, during other seasons, mesofauna showed a clear shift in distribution towards the subcanopy areas. Unfavorable microclimatic conditions during the summer and cold seasons led to a redistribution of mesofauna to deeper soil layers or subcanopy habitats, with potential consequences for nutrient cycling and organic matter decomposition in outdoor areas.
