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)

91 sample plots have been selected on the examined place from a 2 x 2 m quadrate according to BRAUNBLANQUET method (1964). The places of sampling have been marked on the ground (Fig. 1), thus, in the future it is possible to follow up the temporal changes of the vegetation. The samples have been classified by agglomerative methods based on the JACCARD and CZEKANOWSKI similarity functions and the average reduction strategy. The data matrix has been analysed by principal component analysis, as well, by means of the SYN-TAX III package (PODANI 1988). The four largest sample groups have been analysed statistically on the basis of their species' characteristics (floral element, cenological character, life-form, ecological parameters: requirements for soil pH, temperature, water and nitrogen) (Soo 1964-80). The values of the features characterizing the sample groups have been calculated according to percentage pro rata, that is, the sum of the presences concerning one feature has been expressed in percentage of all presences of all species. The species composition of the sample groups has been compared with the similar data of ZÓLYOMrs summary tables (1958). RESULTS AND DISCUSSION GENERAL DESCRIPTION OF THE VEGETATION The south and southeast facing steep slopes of Odvas Hill are covered by an open dolomite rocky grassland community passing a rocky slope steppe community on the lower, gentle slopes. This community gives away the steppe meadows on the foot of the hill, on loess. Open rocky grassland occur in W exposure, in fact in NW exposure, too, on the slopes having similar steepness as on the S exposure of the hill. This association strikingly has more Anthyllis vulneraria at many places. Closed dolomite rocky grassland is on the north, northeast facing slopes, this community passes through to the east Fig. 1. Places of the sample plots on the Odvas Hill Annls hist-nat Mus. nam. hung., 83,1991