Ábrahám Levente (szerk.): Válogatott tanulmányok VI. - Natura Somogyiensis 19. (Kaposvár, 2010)

ERDŐS L., BÁTORI Z., MORSCHHAUSER T., DÉNES A. & KÖRMÖCZI L.: Transitional plant communities of the Villány Mts

38 NATURA SOMOGYIENSIS • • a W6 x Top-forest A Closed rock sward • • O North-cxposed shrubforest + Open rock sward • South-exposed shrubforest Fig. 2: Ordination scattergram of the Canonical Correspondence Analysis. For simplicity, only four ecological indicator values are shown quent species are Allium flavum, Dianthus giganteiformis, Helianthemum ovatum, Koeleria cristata, Melica ciliata and Orlaya grandiflora. In the case of the woody habitats (Helleboro odori-Spiraeetum mediae and Inulo spiraeifoliae-Qercetum pubescentis), species of beech and oak-hornbeam forests have greater relative abundances, due to the shading. Corydalis cava, Galanthus nivalis and Moehringia trinervia are especially typical. Xerotolerant species occur mainly at the edges of the stands, where more light reaches the field layer. The analysis of the ecological indicator values also emphasizes the dual character of the communities (Tables 1-3). Although proportion of T5 (species of the montane mesophilous broad-leaved forest belt), T6 (species of the submontane broad-leaved forest belt) and T7 plants (species of the thermophilous forest or woodland belt) is the greatest, T9 species can also be found in every community (besides Ruscus aculeatus, which is quite frequent in the beech and oak-hornbeam forests in the region, the following species: Asplenium javorkeanum, Artemisia alba, Festuca dalmatica and Pisum elatius

). In the case of humidity values, W1 plants (species of extremely dry habitats or bare rocks, e. g. Artemisia alba, Festuca dalmatica, Sedum spp., Thymus spp.) and W7 plants (species of moist soils not drying out and well aerated, e. g. Arum maculatum, Cystopteris fragilis) occur within the very same vegetation units. In the case of the N-values, maxima are at N2 (species of habitats very poor in nitrogen). However, it is interesting that spectra are ranging from N1 (plants occuring on soils extremely poor in mineral nitrogen) to N9 (plants occuring on soils extremely rich in nitrogen). The Canonical Correspondence Analysis shows that there are at least 3 ecological factors responsible for the vegetational gradient: temperature, moisture and nutrient-content of the soils (Fig. 2). According to this ordination, the northern side has a cooler microclimate, whereas the southern side is hotter, with the highest rate of the termofrequent species (for example T8 species). The oak-hornbeam forest and the scree-forest grow in the moistest habitats. The rate of the species with higher moisture requirement (for example W6 species) is the highest here. The top-forest is drier, the closed rock sward