The effect of mechanical site preparation on sandy soil properties in Scots pine plantations

Sandy soils represent an extreme environment for tree growth. Traditionally, site preparation before planting involves removing logging residues (LRR) and ploughing. An alternative method is incorporating logging residues (LRI) into the topsoil which may enhance tree regeneration and seedling growth. The aim of this study was to assess whether and how different site preparation techniques affect soil physico-chemical and microbial properties over the long term. The study was performed in the Záhorská nížina lowland (Slovakia) in September 2020. Soil samples were taken in two 25-year-old Pinus sylvestris (L.) plantations along five soil profiles in each stand, down to a depth of 30 cm. Results showed a significant increase in carbon and nitrogen concentration and soil moisture in the LRI plot. However, soil pH and phosphorus content significantly decreased. No significant differences were observed in calcium, magnesium, and potassium concentrations between the differently treated plots. The LRI plot also exhibited a significant increase in microbial biomass carbon, N-mineralisation, and catalase activity. The results indicate that different mechanical site preparation methods may impact soil properties over the long term, likely through improved seedling survival and tree growth.