Slávka Tóthová

The paper is focused on the evaluation of long-term changes in the chemical composition of precipitation in the mountain forests of Slovakia. Two stations with long-term measurements of precipitation quality were selected, namely the station of the EMEP (European Monitoring and Evaluation Programme) network Chopok (2008 m a.s.l.) and the station of the ICP Forests (International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests) network Poľana-Hukavský grúň (850 m a.s.l.). All basic chemical components were analyzed, namely sulfur (S-SO4), nitrogen (N-NH4, N-NO3), and base cations (Ca, Mg, and K) contained in precipitation. The time changes of the individual components were statistically evaluated by the Mann–Kendall test and Kruskal–Wallis test. The results showed significant declining trends for almost all components, which can significantly affect element cycles in mountain forest ecosystems. The evaluated forty one-year period (1987 to 2018) is characterized by significant changes in the precipitation regime in Slovakia and the obtained results indicate possible directions in which the quantity and quality of precipitation in the mountainous areas of Slovakia will develop with ongoing climate change.

The effect of wood ash (WA) fertilisation on chemical and biological properties of forest floor layers was studied in a Norway spruce (Picea abies (L.) Karst.) stand in the central part of Slovakia at an altitude of 1300 m above sea level. In the forest floor, litter (OL), fragmented (OF), and humic (OH) horizons with average thickness of 1.5, 2, and 4 cm, respectively, could be distinguished. Three replicates of two wood ash treatments (3 and 6 t·ha⁻¹) and a control were established in the autumn of 2012. Soil samples from OL, OF, OH and A-horizon were taken 0.5, 1, 6 and 12 months after the WA application. In soil samples chemical (pH, C and N content, C:N ratio, concentration of exchangeable Ca, Mg and K) and microbial properties (basal respiration, catalase activity, structure of microbial community based on BIOLOG assay) were determined. Our results showed that the changes in microbial and chemical properties do not occur simultaneously in particular horizons. WA application in autumn lead to a significant increase in pH, base cation concentration, and distinct losses in C and N content in the OL layer in the first month; however, at the beginning of the vegetation period, the most pronounced effect of WA was observed in OF and especially OH horizons; no changes were found in the A-horizon. Different properties of particular forest floor horizons led to a vertical stratification of the microbial community. Each forest floor horizon had particular properties, leading to a vertical stratification of the microbial community; deeper horizons had more homogenous functional groups.