Phytosociological approach to scree and ravine forest vegetation in Slovakia

Abstract

The aim of the study was to perform phytosociological revision of the scree and ravine forest vegetation in Slovakia in order to identify i) basic vegetation units of vegetation according to their floristic composition, and ii) to find out the main environmental gradients affecting their compositional variability. Releves originally assigned to broadly comprehended alliance Tilio platyphylli-Acerion (974 releves) were used for the analyses. In order to select final dataset (527 releves), formal criteria, such as tree layer cover >50%, releve area of 200–500 m 2 and presence at least two from six traditionally accepted diagnostic species of the alliance in Central Europe ( Acer platanoides , Lunaria rediviva , Phyllitis scolopendrium , Polystichum aculeatum , Tilia platyphyllos and Ulmus glabra ) were applied to the primal dataset. Altitude, aspect, slope, climatic characteristics (mean annual precipitation and air temperature), geological bedrock and Ellenberg indicator values (EIVs) were specified for each phytosociological releve. We used modified TWINSPAN algorithm for classification, Detrended Correspondence Analysis (DCA) for explanation of species composition-environmental relationships, and both ANOVA corrected using modified permutation test and Mann-Whitney U-test to test environmental differences at each step of division by numerical classification. Two alliances, Melico-Tilion platyphylli and Tilio platyphylli-Acerion were distinguished with three ( Aceri platanoidis-Tilietum platyphylli , Scolopendrio-Fraxinetum and Seslerio heufleranae-Quercetum petraeae ) and two ( Mercuriali perennis-Fraxinetum excelsioris and Lunario redivivae-Aceretum pseudoplatani ) associations, respectively. Besides the floristic composition, other important factors for differentiation of the associations were altitude and related climatic characteristics. The main environmental characteristics affecting the overall compositional variability of studied forests were EIVs for light, moisture, soil reaction and temperature. The complex syntaxonomical revision identified five floristically and ecologically clearly differentiated associations, what reduced the number to almost half of previously distinguished communities from the territory of Slovakia. Moreover, presented concept is at alliance level in accordance with recent European classification approach.