A survey of forest pollution with heavy metals in the Natural Forest Region (NFR) Moravskoslezské Beskydy with particular attention to Jablunkov Pass

A survey of forest nutrition was carried out in Natural Forest Region (NFR) No. 40 Moravskoslezské Beskydy. The reason for this survey was the gradually worsening state of forest stands in this region and especially in a part of it - in the Jablunkov Pass. Air pollution was the suspected cause of the unfavourable development. According to methodology established for the survey of forest nutrition, the samples of soil and assimilatory organs were collected at 375 sampling sites. The spatial distinctness of Jablunkov Pass was expressed on the basis of selected soil characteristics (quantity of organic material, exchangeable pH, content of total nitrogen, zinc, lead, chromium, cadmium) and of the contents of chemical elements (total nitrogen, magnesium, zinc, lead, chromium, cadmium) in two-years-old Norway spruce needles. These analyses were done by the software Statistica. The medians of concentrations of elements in two-years-old Norway spruce needles in the area of NFR except Jablunkov Pass are: Zn - 34, Pb - 0.71, Cd - 0.15 and Cr - 0.38 (mg/kg). In the area of Jablunkov Pass: Zn - 43, Pb - 12.1, Cd - 0.25 and Cr - 0.41 (mg/kg). Particular attention was paid to the content of heavy metals both in the whole area of NFR and in the area of Jablunkov Pass particularly. The spatial homogeneity is disturbed by the influence of air pollution there. Markedly higher contents of zinc, lead and cadmium are found in the whole soil profile, in the case of chromium in the forest floor only. The distribution of heavy metal contents in the soil profile is influenced by the quantity and quality of organic matter and by the altitude of sampling sites. The higher values of medians of zinc, lead and cadmium contents are found in the area of the Pass. Chromium is an exception with the highest contents found in the southern part of NFR. The medians of concentrations of elements in the forest floor of Norway spruce stands in the area of NFR except Jablunkov Pass are: Zn - 70.6, Pb - 88.6, Cd - 6.4 and Cr - 0.69 (mg/kg). In the area of Jablunkov Pass: Zn - 103, Pb - 138, Cd - 8.8 and Cr - 1.02 (mg/kg). The spatial distinctness of the area around the Jablunkov Pass is confirmed by the evaluation of the data of forest nutrition survey. Particularly, it consists in the high contents of phytotoxic heavy metals. The exceptionally high pollution of this area can be a cause of the physiological weakness of trees with following attack of the honey fungus.