L. Hably szerk.: Studia Botanica Hungarica 23. 1992 (Budapest, 1992)

Dobolyi, Konstantin Z.: Vegetation studies on the rocky grasslands of Hór Valley (Bükk Mountains, Hungary)

The four largest sample groups were analysed statistically on the basis of their species' characteristics (floral element, cenological character, life form, ecological parameters: requirements for soil pH (R), temperature (T), water (F) and nitrogen content of soil (N) (SOO 1964-80)) and nature conservation rank (SIMON 1988). The values of features characterizing the sample groups have been calculated according to percentage pro rata of plant mass, that is the sum of the transformed cover values concerning one feature has been expressed in percentage of sum of all cover values of all species. (One species may belong to several categories with respect to several features, so the sum of percentage values may exceed 100 %). RESULTS The examined grasslands are floristically very rich: 123 vascular plant species have were found in the 200 square metres covered by the samples (Table 1). The dendrogram was cut at 0.58 similarity level. As a result of the classification we gained four larger samples groups as well as some smaller ones. The four larger sample groups consist of: 1=6,11=9,111=8 and IV= 13 samples (Fig. 1). According to the floral composition and the constancy values samples of all the four groups belong to the Seslerio-Festucion pallentis Klika association group. Floral elements which express relatively small phytogeographical area appeared in high quantities in all four groups (Table 3). In the distribution of the floral element spectrum it is remarkable that in group I the proportion of Mediterranean, Pontic, Pannonian and Continental elements is the highest. Group IV is the richest in Carpathian, Balkanian and Alpine elements. Plants respond to particular environmental circumstances of rocky grasslands (dry, shallow soil, extreme micro-climate) with special life forms. Accordingly Chamaephyta and Therophyta species are found in high proportion on the studied sites (Table 4). As expected, in the distribution of cenological characters rock-grass elements (Festuco-Brometea, Festucetalia valesiaceae, Festucion) are predominant (Fig. 2). The considerable proportion of Quercetea pubescenti-petraeae species may be explained that these grasslands are of relatively small area, surrounded by forests and forest-species invade into these sites. Considering the distribution of cenological spectrum, group I is the most intact rocky grassland. Chenopodietea and Secalietea elements indicate degradation of the vegetation, which observations show to be due to tourism and high game density. Considering the cenological spectrum, sample groups II and III are the most degraded. Because of the species richness and their intact state the rocky grasslands are of outstanding importance for nature conservation. The analysis based on nature conservation ranks (SIMON 1988) shows the high value of the studied sites. The ratio of protected species is particularly high, especially in groups I. and IV. (Fig. 3) Analyses of the ecological requirements gave results as expected: limestone