Effects of (Cydalima perspectalis Walker) on the quality characteristics of leaf litter and soil (Case study: Cheshmebalbel Boxwood Reserve, Bandargaz, Golestan Province)

In this study, the impact of boxwood moth pest defoliation on the dynamics of leaf litter and soil nutrients in the Cheshmebolbel boxwood (Buxus hyrcana) reserve was evaluated. A random sampling technique was employed to collect litter layer samples (using a 400 cm2 frame) and soil samples (using a metal cylinder with an 8 cm diameter and a 10 cm depth) from 32 sites in unpolluted and polluted boxwood stands. The results revealed that only soil moisture percentage differed significantly among the soil physical variables, whereas all chemical soil variables showed significant differences between the two polluted and unpolluted boxwood sites. Furthermore, basal respiration (0.14, 0.12), metabolic rate, microbial ratio, and carbon availability index were significantly higher in the polluted sites compared to the unpolluted site, while no significant difference was observed based on the microbial-carbon respiration index. The principal component analysis (PCA) results demonstrated a distinct separation of the two sites, both polluted and unpolluted, along the first axis, based on both litter and soil variables. In this context, nitrogen, metabolic rate, moisture, nitrate, ammonium, and stimulated respiration (0.30, 0.39) exhibited a positive correlation with the first axis, representing the concentration of the unpolluted stand. On the other hand, C/N ratio, potassium, magnesium, calcium, and microbial biomass carbon displayed a negative correlation with the first axis, representing the concentration of unpolluted sites. In general, the findings of this research underscore the substantial influence of defoliation induced by pest outbreaks on an important aspect of forest ecosystem health, performance, and nutrient cycling.