Acta Botanica 41. (1998)
1998 / 1-4. szám - KEVEY BALÁZS - BORHIDI ATTILA: Top-forest (Aconito anthorae-Fraxinetum orni) a special ecotonal case in the phytosociological system (Mecsek Mts., South Hungary)
TOP-FOREST (ACONITO ANTHORAE-FRAX1NETUM 0RN1) 29 Fraxinetum orni (A. O. Horvát 1958) Soó et Borhidi in Soó 1962), and the mesophilous montane oak-hornbeam forests (Asperulo taurinae-Carpinetum Soó et Borhidi in Soó 1962) and beechwoods (Helleboro odori-Fagetum Soó et Borhidi in Soó 1962) on deep soils of the cold northern slopes. For all the communities discussed are characteristic the frequent occurrence of the species with sub-Mediterranean, Balkanian and west-Balkanian (Illyrian) distribution. Aremonio-Fagion and Quercion fametto elements are the most important from phytosociological point of view. The hairy oak-chestnut oak forest (Tamo-Quercetum virgilianae Borhidi et Morschhauser in Borhidi and Kevey 1996) The hairy oak-chestnut oak forest lives in the central Triassic limestone massive of the Mecsek Mts covering the relatively steeper (10-35°) southern slopes on shallow rendzina soil. The cover (60-80%) and height (10-15 m) of the canopy is less than those of the top-forest. Its characteristic species is the hairy oak complex (Quercus pubescens agg., mainly the chestnut oak: Q. virgiliana) and the flower ash (Fraxinus ornus) with scattered individuals of Quercus cerris, Sorbus torminalis and Tilia tomentosa. The shrub layer is strongly developed, with 40- 80% of cover and 4-8 m of height. The most abundant species is Cornus mas, other frequent ones are the Euonymus verrucosus, Lonicera caprifolium, Rosa arvensis and Viburnum lantana. The outstanding characteristic of sub-Mediterranean type is the richly evolved layer of lianas composed of Tamus communis, Lonicera caprifolium and Hedera helix. They interlace the individuals of the shrub layer into a green wall and climb up to the trunks of the trees as well. The cover of the herb layer varies between 50 and 80%. Dominant species may be the Carex humilis, Melica uniflora and Tamus communis. A definitive role is played by the xerophilous grassland elements (Festuco-Brometea and Festucetalia valesiacae elements) in the composition. Among the studied communities this association is represented by the thermo-xerophilous oak-forest elements (Quercetea pubescentis-petraeae, Orno-Cotinetalia, Quercetalia cerris, Quercion farnetto etc.) with higher frequency. In contrast, the species of the mesophilous forests (Fagetalia, Carpino-Fagetea) occur less frequently in this community. From the top-forest it differs with the high presence of the following species: Ajuga genevensis, Brachypodium pinnatum, Bromus pannonicus, Campanula bononiensis, Carex flacca, Erysimum odoratum, Euphorbia cyparissias, Galium lucidum, Flieracium bauhinii, Lonicera caprifolium, Muscari tenuiflorum, Poa pratensis, Prunus spinosa, Teucrium chamaedrys etc. (see Tables 1, 6-10). Acta Bot. Hung. 41, 1998