B. Papp szerk.: Studia Botanica Hungarica 33. 2002 (Budapest, 2002)

Dobolyi, Konstantin: Studies of vegetation dynamics on the rock grasslands in Csíki-hegyek (Budaörs, Hungary)

rocks (Fago-Ornetum), 3) pubescent oak scrub woodlands, 4) "rock steppes", 5) open and closed dolomite rock grasslands. These, except for Fago-Ornetum, can still be found in Csíki-hegyek, although in most cases not on their original places, not in the original extent and not in their original state. The most important manifestation of human activity is that forests have been cut for several hundreds of years and the cut-over areas were pastured intensively. Pasturing caused intensive erosion and initiated the development of secondary rock grasslands and rock steppes. In present days, first of all, very intensive tourism is the most prominent human pressure, which results in significant changes of the vegetation. Trampling causes decrease of vegetation diversity and growing surfaces of devastated areas. The continuous degradation of dolomite grasslands has been observed for a long time, but neither in Csíki-hegyek, nor in other dolomite regions of Hungary has been studied up to date. In spite of its degraded and secondary state, Csíki-hegyek is a particularly valuable and strictly protected territory of the Buda Mts Landscape Protection Area. The number of protected plant species living here is over 50, and some of them are Carpathian and Pannonian endemic ones. Botanical study and vegetation mapping of this area were carried out in 1996 done on commission of the Buda Mts Landscape Protection Area (DOBOLYI 1996). As part of the study, anthropogenic change of dolomite grasslands has also been investigated. Observations of botanists and the local nature protection staff show that these grasslands exhibit slow degradation, in other words, they are not in an equilibrium state. Better knowledge of these processes is essential for nature conservation. The aim of my investigation was to follow the procession of vegetation dynamics, that is, to provide an exact documentation and monitoring of temporal changes of vegetation. I used the method of fixed phytosociological relevés, which in my view provides the most exact data about vegetation dynamic processes in a short period of time. As for the investigated vegetation types, rock grasslands, rock steppes and their transitional stands were chosen because of their natural merits and because they are particularly sensitive to environmental changes and degradation effects. (According to multivariate analyses dolomite rock grasslands and rock steppes do not segregate sharply (PODANI 1998)). The following four sites were subject of the investigation: Odvas-hegy (47°28'5"N, 18°56'53"E), Szekrényes-hegy (47°28'34"N, 18°56'14"E), Farkashegy (47°28'24"N, 18°56'28"E) and Kő-hegy (47°27'53"N, 18°57'22"E). At these sites there are large, homogeneous grassland areas of natural condition but change of their vegetation is expected or possible. The exact localities of the relevés were