Few studies in arid and semi-arid regions have focused on the efects of natural and aforested woody species on the dynamics of soil physicochemical and biological properties during diferent seasons. This study investigates the efects of aforested woody species including native and non-native introduced species in a semi-arid forest region of Iran. Soil sampling was done beneath the canopy of mentioned woody species and outside the canopy in spring and summer (48 soil samples: 8 patches [7 species and control]×2 seasons×3 replicates). Three soil cores (with 25 cm in diameter; 20 cm in height) were randomly extracted and then mixed to produce one composite sample. The results showed that season and species had a signifcant efect on most soil chemical parameters including calcium carbonate (CaCo3), available phosphorus (Pava), available potassium (Kava), Acidity (pH), electrical conductivity (EC) and calcium (Ca). In addition, the season and species had a signifcant efect (P<0.05) on water content (WC). The efect of woody species on soil biological attributes was greater than the season as diferent woody species signifcantly changed the basal respiration (BR) and substrate induced respiration (SIR), microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), microbial biomass phosphorous (MBP), and alkaline phosphatase. Duncan's multiple mean comparison showed that WC, organic carbon (OC), total nitrogen (Ntot), Pava, Kava, Ca, MBC, MBN, MBP under the Quercus brantii trees (natural and plantation) were more than Amygdalus scoparia and also A. scoparia were more than Pinus eldarica (PIN) and Cupressus arizonica (CUP). In addition, the amount of nutrients and soil biological activity beneath these non-native plantations decreased compared to the native plantation species. It can be said that in order to improve soil quality in semi-arid region, preservation of existing natural species should be prioritized and if necessary, plantation with native species should be considered.
