EN
The objective of the study was to determine the dynamics of soil temperature on inland dunes in the Toruń Basin (N Poland) with reference to the two methods of site preparation: homogenization of belts with a forest mill (FR) and preparation of trenches with a double−mouldboard plough LPZ−75 (LPZ). The study was conducted in a young Scots pine (Pinus sylvestris) plantation on plots with soil prepared by a forest mill on north− and south−facing slopes of a dune (FR−N and FR−S respectively) and with soil prepared with a plough on the ridge of a small aeolian mound (LPZ). On each plot a soil pit was dug and soil samples were taken from distinguished horizons for laboratory analyses. Besides, from April to December of 2013, at interval of ca. two weeks, soil temperature was measured at the depths of 3, 10, 25 and 50 cm. To estimate daily amplitudes of temperature in topsoil on the studied plots, in a sunny summer day (23.08.2013) the temperature was additionally measured from 5 a.m. to 9 p.m. with an hourly interval. These measurements were taken at the two upper depths (3 and 10 cm). Despite the fact that soil surface was distinctly darker for belts prepared with a mill than in trenches prepared by a plough, soil temperatures were almost regularly lower in FR−N and in FR−S than in LPZ. This concerns all the investigated depths. The differences were explained by much higher moisture of soil material in belts what involves higher thermal capacity and with that slower heat of a soil, as well as causes higher losses of thermal energy for evaporation. Another agent explaining this was indicated to be related to high porosity of materials found in the belts. Namely, especially in dry periods, high volume of soil pores are filled on the FR plots with air what impedes heat transfer in a soil. It was concluded that stated in a previous study worse growth of pines planted in milled belts than in tranches prepared with a plough was unlikely related to differences in soil thermal conditions. Thus, differences in growth dynamics of young pines in plots with site prepared by the two studied methods are caused by other reasons rather as primarily other competitive impact of weeds and differences in soil water conditions occurring at root system of young trees.