Ground vegetation as an important factor in the biodiversity of forest ecosystems and its evaluation in regard to nitrogen deposition

We documented the current typological and phytosociological characterisation of the ground vegetation as an essential component of biodiversity in 154 Czech forest monitoring plots and to describe its changes during the past 15 years in regard to the deposition and concentration of nitrogen in the soil. Plots were classified as vegetation units in accordance with the UNECE and FAO nomenclature and on the basis of their potential natural vegetation and compared in terms of the occurrence and coverage of the indicative selected nitrophilous species. In all the soil horizons tested statistically significant differences in the C/N ratio were observed between areas with and without the presence of certain selected nitrophilous species (Geranium robertianum, Impatiens parviflora, Sambucus nigra, Urtica dioica). In the areas with the presence of the Geranium robertianum and Urtica dioica species, statistically significantly higher concentrations of nitrogen were recorded in some soil horizons than in those areas with the absence of these species. The findings concerning the influence of nitrogen on nitrophilous herbaceous indicators were compared with the European results obtained in the framework of the ICP Forests international programme and with those of other foreign studies.