Atmospheric deposition of sulphur and nitrogen oxides in our country has decreased drastically since the second half of the 1980s (by more than 87% and 51%, respectively). It might therefore seem that these elements are slowly disappearing from ecosystems, as is the interest of the scientific community in them. Recently, however, it has become clear that we will not just get rid of these relics of the Czechoslovak industrial past.
For three years, samples were taken monthly from the individual soil horizons in the Jizera Mountains in order to determine the concentrations of SO4 (-II) and NO3 (-I). Two sampling sites were located under the spruce and beech vegetation. The aim of the study was to describe seasonal changes in the concentrations of the above-mentioned oxides depending on the "land-cover" (i.e. beech vs. spruce).
In both forest types, the concentration of NO3 (-I) decreased with depth, but in the soil under the beech stand, the compound was found in larger amounts. On the contrary, the concentration of SO4 (-II) culminated under the spruces in the lowest layer, but in beeches again in the upper mineral horizon. There were the least sulphates in the organo-mineral A-horizons under both stands. Overall, there was a more acidic soil under the spruce stand. Thus, the differences between beech and spruce forest can usually be justified by the different characteristics of both stands. This is, for example, a fall of leaves or a larger surface of needles, thanks to which conifers are more effective in "combing" these substances from the atmosphere. As a result, precipitation deposition under spruce trees is more acidic.
However, the increasing trend of absolute concentrations of both anions during the experiment, which was shown equally by both stands, was quite surprising. This indicates the long-lasting effect of the compounds on the soil. It is therefore important to realize that, for example, the current increasing emissions of nitrogen oxides from road transport may pose a serious threat to sensitive soil ecosystems, and therefore to humans, in the future. It is possible that even after the introduction of countermeasures, which will lead to an overall reduction in emissions, nitrogen oxide concentrations will continue to rise for a long time.
Tejnecký, V., Brázdová, M., Borůvka, L., Němeček, K., Šebek, O., Nikodem, A., Zenáhlíková, J., Rejzek, J., Drábek, O. (2013): Profile distribution and tempoval ganges of sulphate and nitrate contents and related soil properties under beech and spruce forests. Science of Total Environment 442, 165–171.
Ing. Jitka Zenahlíková, Ph.D.
She graduated from the Faculty of Forestry and Wood Sciences at the CULS with a doctoral degree in Forest Cultivation and currently works in the Šumava National Park as a clerk in the monitoring department.
Prepared by: Jiří Lehejček