ABSTRACT Afforestation plays a crucial role in rehabilitating degraded ecosystems and improving soil and environmental conditions in arid and semi‐arid regions. Although many studies have shown that afforestation improves soil properties, the combined effects of slope, aspect, and microtopography on soil biochemical responses remain poorly understood. Furthermore, environmental characteristics, particularly aspect and slope percentage in mountainous forest ecosystems, play a key role in determining the extent of its impact. This study investigated the impact of afforestation using the wild almond ( Amygdalus scoparia Spach) on the physical, chemical, and biological properties of soil across different aspects, slopes, and canopy positions. To conduct this research, a total of 72 soil samples were collected in spring from northern and eastern aspects in two slope classes (less than 10% and more than 40%) and three positions (Under canopy upslope UCU, Under canopy downslope UCD, and control). The physical, chemical, and biological soil properties were then measured in the laboratory using standard methods. The results showed that saturated point (SP) (39.48 ver. 36.39), sand (25.33 ver. 23.50), clay (32.44 ver. 28.72), organic matter (OM) (2.2 ver. 1.93), and total nitrogen (N) (0.1 ver. 0.09) were higher in the northern aspect than in the eastern aspect, while the BD (1.18 ver. 1.08) was higher in the northern aspect than in the eastern aspect. On slopes of less than 10%, the soil had higher amounts of pH (7.31 ver. 7.24), SP (37.93 ver. 35.99), OM (2.06 ver. 2.16), and N (0.1 ver. 0.07), phosphorus (P) (283 ver. 199) and potassium (K) (287 ver. 193). The highest levels of the urease enzyme (μgρ NH4 Nml‐5dwt 2 h − 1 8) were observed on slopes with less than a 10% incline and at the UCD (8.26). The lowest levels were observed on slopes with an incline above 40% and in the control position (μgρ NH4 Nml‐5dwt 2 h −1 2). Additionally, enzyme activity was higher in the northern aspect than in the eastern aspect (i.e., phosphatase activity = 901.39). These results indicate that afforestation positively impacts quality‐related indicators, including soil respiration, porosity, urease and phosphatase enzymes, and OM and nutrients in the soil. Generally, soil is more fertile on slopes of less than 10%, on northern slopes, and on UCD. This research aims to restore this valuable ecosystem and ensure the region's sustainability, which can lead to improved soil quality and increased ecosystem sustainability. Future restoration efforts in semi‐arid mountains should prioritize planting A. scoparia on northern and downslope positions to enhance soil moisture, fertility, organic carbon, and ecosystem recovery efficiency.
Bagheri et al. (Fri,) studied this question.