The aim of the research was to study the influence of different tree stands on topsoil magnetic susceptibility and heavy metal contamination in the soil. The study was performed in the old park in Pruhonice (near Prague) in the Czech Republic. On the relatively small area of Pruhonice Park, five different coniferous tree species (pine, spruce, blue spruce, fir, Douglas fir) and five deciduous species (beech, red oak, common oak, hornbeam, birch) were found, growing in small clusters on the same geological background. Also other natural and anthropogenic factors such as distance from industrial and urban sources of pollution, type of soil, climate, etc. were similar. The magnetic susceptibility was measured directly in the field. Twenty topsoil cores 0.3 m long (2 under each tree species) were collected and also soil samples from under each tree (litter horizon) were taken. The magnetic susceptibility values of the topsoil profiles and of litter layer samples were obtained. Heavy metal analyses of surface samples (litter horizon) were also carried out. The field magnetic susceptibility (K) data are more or less comparable to the laboratory data (x). High heavy metal contents corresponding to high magnetic susceptibility values are observed in the litter horizon. A positive correlation between magnetic susceptibility and some heavy metals was observed. The results suggest that the type of forest may also influence the values of magnetic susceptibility and heavy metal content. Generally higher magnetic susceptibility values were observed in the coniferous forest, except for the surface layer (litter horizon) where the K values are lower than in the deciduous forest.

The aim of the study was to estimate the influence of metallurgical slag on heavy metal concentration in tree species. The research included pH-reaction and conductivity of slag samples, heavy metal content (Pb, Zn, Cd, Cu, Ni) in slag, needles and leaves samples. The waste material is covered by vegetation and fulfils a soil function. The vegetation is self-sending. The plant cover being a result of natural succession consists of weeds, grasses, perennials, bushes and trees. Dominant tree species are birches and willows as well as poplar and pine. In slag samples are observed the raised concentration of cadmium, lead and copper. The low content of zinc is surprising. In tree material observed excessive heavy metal concentration especially lead and cadmium. Their accumulation is undoubtedly depended on tree species, but in this case heavy metal content in plant samples is a result of their presence in slag material. The higher heavy metal content in slag results the higher concentration in needles and leaves (probes S1 and S2, T1 and T2). Exception to this rule is the birch - probe B,, but in this case the pH is crucial. In samples with pH over 6.8 heavy metal mobility, their solubility and phytoavailability decrease. pH below 7 results in higher trace element uptake in plants.