Evaluation of soil properties in variously aged Scots pine plantations established on sandy soil

Pines are widely planted for sand dune stabilization and their cultivation results in the changes in physical, chemical, hydro-physical and water repellency properties. Soil properties were evaluated at three Scots pine plantations (PF1, PF2 and PF3) close to Studienka village, Borská nížina lowland (southwestern Slovakia) during hot and dry summer period. The PF1 site is a newly established plantation, the PF2 site is about 30 years old plantation, and the PF3 site is about 100 years old plantation. Here, we estimated the differences in pH, soil organic carbon content, C_ox, particle size distribution, PSD, saturated, ks, and unsaturated, k(–2 cm), hydraulic conductivity, water, S_w, and ethanol, S_e, sorptivity, water drop penetration time, WDPT, and repellency index, RI. It was found that C_ox varies most significantly with plantation age, and relative differences in PSD and pH were lower than the relative difference in C_ox. The PF3 site differs the most from the other two, especially in C_ox and in the content of sand fraction. It can be attributed to the older age of the plantation, which represents a more advanced stage of succession accompanied by an accumulation of soil organic matter. Relationships between C_ox, k(–2 cm), RI, and WDPT and pine forest age were described by appropriate mathematical models. We found a similarity between k(–2 cm) and RI relationships vs. pine forest age (exponential models), and between Cox and WDPT relationships vs. pine forest age (first and second-order polynomial models). The latter similarity can be supported by the fact that soil water repellency is induced by the hydrophobic and amphiphilic components of soil organic matter.