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Szerdahelyi, Tibor: Vegetation studies on rocky grasslands in the Pilis Mountain (Hungary) II.
Festuco-Brometea (B, C) elements is the lowest at site III. The quantity of Quercetea elements is the highest at the site VII. The distribution of the life-forms can be seen on Fig. 3. The high level of the therophyton and the hemitherophyton species (Th, TH) is characteristic. The level of the other elements (Ch, G, H) is comparatively constant. The distribution of the H values is shown at the 8 sites on Fig. 4. All of the sites have almost the same number of indifferent (Ro) species. At site II, we could see a kind of nivellation of the R values which is a sign of the degradation. On Fig. 5. we can see the distribution of the T values. The quantity of the indifferent (T 0 ) species is almost the same on all sites. At the sites I-IV, the Ti elements are present, while these values are missing on the sites V-VIII. The distribution of the water requirement of the 8 sites (F) is shown on the Fig. 6. We can see that the level of the indifferent elements (F 0 ) is very low, somewhere they are missing. The appearnace of the xerophilous communities is the most characteristic at the site I and site VIII. The influence of the milder exposition is shown at the sites III, V, VI, VII. On the site IV, the F4 elements appear. This is caused by the microrelief (valley influence). The distribution of the N requirement can be seen on Fig. 7. The number of indifferent species (N 0 ) is very few, on site V they are missing. The lowest level of the N3 elements is on the site VIII. The quantity of Ni elements is the highest on the sites I and VIII. Probably, this is the native condition of the communities. Running data, we gave the result the clustering of a matrix of the Czekanowski's similarity index. There are three centres in the dendrogram. Several samples are obtained only at 0.65 value. There is no close connection among them (Fig. 8). This dendrogram shows that the individual differences dominate among the samples, more than the connection among the sites. Acknowledgements are due to Dr. M. RAJCZY for his advice on suitable methods for the computer analysis. REFERENCES BRAUN-BLANQUET, J. (1964): Pflanzensociologie. - Wien-New York, 865 pp. MAAREL, E. van der (1979): Transformation of cover-abundance values in phytosociology and its effects on community similarity. - Vegetatio 39 (2): 97-114. MÁTHÉ, I. (1956): Vegetációtanulmányok a Nógrádi Flórajárás területén. (Vegetation studies in the area of the Nógrád flora district). - MTA Agrártudományok Osztályának Közleményei, 9: 1-56. PODANI, J. (1988): Syn-Tax III. User's Manual. - Abstracta Botanica 12: 1-183. POLGÁR, S. (1933): A bakonyi Tbbánhegy vegetációja. (Vegetation of the Tbbánhegy in the Bakony Moutains). - Bot. Közlem. 30: 32-43. PRISZTER, SZ. (1985): Synopsis systematico-geobotanica florae vegetationisque Hungáriáé VII. - Akadémiai Kiadó, Budapest, 683 pp. SOÓ, R. (1930): A modern növényföldrajz problémái, irányai és irodalma. (Problems, directions and references of the modern geobotany). - A Magyar Biológiai Kutató Intézet Munkái, 3:1-37.
