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)

Acta Botanica Hungarica 41 (1-4), pp. 27-121, 1998 TOP-FOREST (ACONITO ANTHORAE-FRAXINETUM ORNI) A SPECIAL ECOTONAL CASE IN THE PHYTOSOCIOLOGICAL SYSTEM (MECSEK MTS, SOUTH HUNGARY) B. Kevey' and A. BORHIDI2 1 Dept. Botany, Janus Pannonius University, H-7624 Pécs, Ifjúság útja 6, Hungary 2Inst. Ecology and Botany, Hungarian Academy of Sciences, H-2163 Vácrátót, Hungary The top-forest has been recently described by the authors. It develops on the flat rocky ridges of the Mecsek and Villány Mts in South Hungary and represents a special case of ecotonal vegetation, where the southern thermophilous elements of the canopy and the meso-hygrophilous plants of the herb layer originating from the shaded oak-hornbeam- and beechwoods of the northern slopes are shifted together and intertexted into a community of special composition. It is a relict community of extremely high biodiversity. Its relations to the other - zonal and extrazonal - forest com­munities are discussed in the article. Key words: beechwood, ecotone, hairy oak-Italian oak forest, oak-hornbeam wood, phytosocio­­logical system, rock-forest, top-forest, turkey oak-sessile oak forest INTRODUCTION The flattening rocky ridge of the Misina-Tubes range (500 to 600 m a.s.l.) is covered by a forest community of special physiognomy and floral composition, which was observed as a possible new one at first by A. Borhidi (ined.) in the early 60s, when studied the Fagion illyricum communities (Borhidi 1963, 1965). Kevey in his univ. doctor thesis (1977) treated this forest as a “hairy oak wood” characterizing it with two phytosociological relevés and a vegetation profile with the following text: “On the ridges the hairy oak wood is in contact with oak­­hornbeam- and beechwoods. Its canopy and shrub layer seems to be a normal hairy oak wood, but in contrast, the herb layer is composed by Fagetalia ele­ments and species of the Corydalis-group are dominating. This phenomenon can be explained in the following way. The change of orography occurring on the ridge effects at first on the macro- and mesoclimatic conditions influencing the composition of the canopy. Being in the sub-Mediterranean belt, macroclimate favours the thermophilous trees in the lower altitudes, consequently the composi­tion of the canopy and the shrub layer corresponds to it. In the beech- and oak­­hornbeam woods climbing up from the northern slopes canopy trees loose their competitiveness against hairy oak and flower ash and give over their places to them. These trees making a good shadow are able to develop favourable micro- 0236-6495/98/$ 5.00 © 1998 Akadémiai Kiadó, Budapest

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