Impact of sulphur and nitrogen deposition on plant species assemblages in natural vegetation

In the present study twelve years of changes in natural plant communities and their relation to S and N deposition are analysed. The Acid-tolerance index (ATI) and Nitrogen-demand index (NDI) based on Ellenberg's indicator values, and the Shannon-Wiener index were employed for characterizing the species assemblages of communities. The deposition at the sites was dramatically higher in the south than in the north of the country. NDI, but not ATI, was significantly correlated to N deposition. Species diversity at each site was quite stable over time. In PCA ordination species diversity, ATI and NDI were almost independent from each other, and were represented by three different principal components. There only NDI was strongly correlated to S and N deposition, while ATI was almost independent of them. Regression analysis suggested that species richness and diversity were weakly correlated to N deposition.