Matskási István (szerk.): A Magyar Természettudományi Múzeum évkönyve 90. (Budapest 1998)

Dobolyi, K.: Phytosociological studies on the andesite rocky grasslands in Visegrád Mountains (Hungary)

ANNALES HISTORICO-NATURALES MUSEI NATIONALIS HUNGARICI VolumeQO. Budapest, 1998 pp. 91-113. Phytosociological studies on the andésite rocky grasslands in Visegrád Mountains (Hungary) K. DOBOLYI Department of Botany, Hungarian Natural History Museum H—

1087 Budapest, Könyves Kálmán krt. 40, Hungary DOBOLYI. K. ( 1997): Phytosociological studies on the andésite rocky grasslands in Visegrád Mountains (Hungary). - Annls hist.-not. Mus. natn. hung. 90: 91-1 13. Abstract - Andésite rocky grasslands were investigated cenologically on the basis of 77 samples at ten sites of Visegrád Mts. The sites were analysed statistically according to the life forms, floral elements, phytosociological characters, social behaviour types, value of naturalness and ecological parameters of the species. The associations of the investigated sites belong to the Asplenio-Festucion pallentis association group. With 15 tables. INTRODUCTION .Silicate parent material of volcanic origin occurs in several parts of the Hungarian Central Mountains. Rocky grassland vegetation has developed on the extreme dry slopes first of all in southern and south-western exposition. Size of grassland plots is different and they often form a mosaic with fragments of shrubbery or xerotherm forests. Typical rocky grassland communities of the Pannonian region were described and classified by ZÓLYOMI (1936, 1966). The andésite rocky grassland vegetation of the Mátra Mountains was studied by KOVÁCS & MÁTHÉ (1964). Exact cenological and ecological analysis of grassland associations in Zemplén Mts. was published by SIMON (1972, 1977). He was the first who applied mathematical processes for calculation of similarity among phytosociological relevés on silicate grasslands. The typical grassland communities developed on silicate parent material belong to the Asplenio-Festucion pallentis association group (ZÓLYOMI 1966). SOÓ (1980) and BORHIDI (1993) also accept this syntaxonomic scheme. However, grassland vegetation very often appears not in typical plant communities, but in forms of different transitions from one assotiation to another and in their degraded forms, too. The aim of this work was to study grassland vegetation developed on andésite in Visegrád Mts. irrespective of whether it appears in typical forms. Visegrád Mts. is a part of the Hungarian Central Mts. and situated north of Budapest. Its territory belongs to the Duna-Ipoly National Park. The average height of the hills where grasslands were investigated cca. 200-550 m above sea level. The parent materials are andésite, andésite tuff and andésite agglomerate.