Mgr. Katarína Gašová: Accumulation of chemical elements and energy in litterfall and forest floor of beech ecosystems of Kremnické and Štiavnické vrchy Mts [PhD thesis] The Institute of Forest Ecology, Department of Soil and Plant Ecology. Supervisor: Ing. Margita Kuklová, PhD. Qualification level: Philosophiae Doctor, 2017The submitted thesis studies the accumulation changes of selected nutrients, risk elements and energy in litterfall and forest floor of beech stands (Fagus sylvatica L.) in the interval of years 1993 and 2014. The study was carried out in phytocoenoses classified into the forest type group Fagetum pauper. They are localized in orographic units of Kremnické a Štiavnické vrchy Mts. In the past, Žiarska kotlina region was significantly affected by poorer air quality as a result of aluminium production and power engineering. Even though, the actions aimed to reduce quantity of emitted pollutants were implemented, the damage caused to the environment is a long-term problem.The results of the statistical analysis (ANOVA, post-hoc Tukey test, correlation analysis) show, that the consequences of air pollution can be seen in the changes of quantity as well as in the quality of the beech ecosystems. The stressed stand showed much larger litterfall accumulation and due to the lower soil reaction, the decomposition process was slowed down and subhorizon Ooh was formed. Statistically significant difference was found out between fermentation subhorizons of monitored plots. We recognized a partial improvement of emission-imission situation in Žiarska kotlina region, based on the considerable change of pH values between subhorizons Oof (5.45) and Ooh (4.66).Within monitored years, we found statistically significant differences between mean content of magnesium (p < 0.05), sulphur (p < 0.01) and aluminium (p < 0.001) in beech litterfall leaves on plot of the Štiavnické vrchy Mts. The differences between calcium content in leaves (both years) as well as in the Oon and Oof subhorizons were statistically significant and their higher amount was recorded in beech forest of Kremnické vrchy Mts. Leaves of stressed stand contained considerably more aluminium in the 90‘s compared to samples from control plot. Twenty years later, the significance of the difference was also confirmed in the arsenic content in the leaves of stressed stand, probably due to a combination of important traffic line, power engineering emission and poor wind circulation of Žiarska kotlina region.