Matskási István (szerk.): A Magyar Természettudományi Múzeum évkönyve 83. (Budapest 1991)

Dobolyi, K., Kováts, D. , Szerdahelyi, T. ; Szollát, Gy.: Vegetation studies on the rocky grasslands of Odvas Hill (Budaörs, Hungary)

for example, the chosen plots of samples) are, among other things that sample group I was made in springtime (spring aspect), therefore, the grass cover and the number of species were relatively low. The similarity of sample groups III and IV are remarkable because the inclination of slope and its consequences - as ecological factors - in our case have greater influences on the vegetation than the exposure of the slope. By knowing of the results of numerical methods the samples were summarised again and the groups from the classification were accepted. The cenological analysis was made in this sample group. THE CENOLOGICAL CHARACTERIZATION OF SAMPLE GROUPS Sample group I has been selected on th W side of the hill, on S exposure, mainly on 35 angle slope, with an average grass covering of 25-30 %. The samples have been taken in springtime, the average number of species was 19. Sample group II has been selected on W exposure, on 10 angle slope, in autumn, the covering average per cent is 90 % (85-100 %), the average number of species was 20. Most of the samples of group III have been taken in NW exposure (3 samples on W, 2 samples on E-NE exposure), the average angle of slope being 35 ((20)-35-40-(45)). The samples have been taken in autumn, and partly in summertime, the average covering per cent was 45 % ((30 %)40 %-(70 %)), the average number of species was 28. Sample group IV has been selected on the E side of the hill, mostly on SE exposure, on (25)-30-35 angle slopes, samples have been taken in autumn, the average covering per cent was 60 % ((45 %)-55 %65 %), the average number of species was 32. Considering the distribution of cenological characters (Fig. 4) the richness in rock grass elements of sample groups III and IV was striking. The Festuco-Bromea and Festuco-Brometea elements are characteristic for sample group II being common in the rock grass and steppe communities. In the distribution of the phytogeographical spectrum (Fig. 5) it is obvious that nearly 30 per cent of the Mediterranean and sub-Mediterranean elements and the relatively high rate of the Pontic, Pannon and Balkan elements are important. Sample group II also differs slightly from the other three groups with respect to this character that appears in high quantities in the Central European, Mediterranean- sub-Mediterranean (34 %) characters and other categories. Fig. 4. Distribution of the cenological characters on the groups