L. Hably szerk.: Studia Botanica Hungarica 20. 1988 (Budapest, 1988)

Szerdahelyi, Tibor: Vegetation studies on rocky grasslands in the Pilis Mountains Hungary

STUDIA BOTANIGA HUNGARICA (Antea: Fragmenta Botanica) XX. 1988 p. 109-117 Vegetation studies on rocky grasslands in the Pilis Mountains Hungary By T. SZERDAHELYI (Received December 8, 1987) Abstract: Cenological investigations on rocky grasslands have been carried out in two sites of the Pilis Mountains in its limestone range. At each of the two sites 25 samples have been examined and compared with each other according to their floral elements, ecological requirements, life-forms and cenological characters. The divergence of the floristic list of two groups has been explained by degradation processes. The data were analysed by cluster analysis with the help of computer. INTRODUCTION The main aim of the Pilis Biosphere Reserve is to preserve the various biotic communities for the future. There are several rocky grassland communities with various species composition on the southwest limestone slopes of the Pilis Mountains. Having originated in the Triassic and having cracked in the Tertiary period, the slopes and cliffs presented various possibilities for the formation of rocky grassland communities. It is possible to compare this long rocky grassland zone (about 14 km) with spots of similar character. The unbroken oak-forest (Quercetum petraeae-cerris) at the top of the slope is fragmented gradually and rocky grassland association patches are organized. The size of these fragments is to a great extent influenced by the microrelief. Treeless communities start from here on xerophilous spots. We marked two areas in this rocky grassland vegetation similar to each other in many characters. These sample plots belong to the Cleistogeno-Festucetum rupicolae association (SOÓ 1964- 1980). SOÔ presented data about this association from the Keszthelyi Mountains, of a "Carex humilis-Festuca sulcata-Stipa joannis association complex" (1930). Later POLGÁR gave a floristic list from a similar association (1933). MÁTHÉ's vegetation studies (1956) provided several detailed pieces of about this association. ZÓLYOMI published in his paper (1958) a floristic list from a "Diplachno-Festucetum sulcatae matricum" association of the Budai Mountains. The object of my study was to examine how changes of the environmental complex influence the changes in the species composition of the rocky grassland community. MATERIAL AND METHOD The first sample area (I) is close to the "Klastrom-szirtek", where 25 quadr.ates each of lxl m were sampled to the BRAUN-BLANQUET method (1964). It was presumed that the changes in the species composition of the rocky grassland community were caused by the excessive mouflon stock. Certainly there are many wild animal tracks in this area. The second