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)
30 KEVEY, В. & A. BORHIDI Southern turkey oak-sessile oak forest (Potentillo micranthae-Quercetum dalechampii Horvát 1981) This association is the zonal vegetation on the slightly acid, brown forest-soil of the highplains and slightly inclined slopes in the lower altitudes of the Mecsek Mts up to 600 m a.s.l. The cover of its canopy is similar to that of the top-forest (70-80%), but it is considerably higher up to 20-30 m of height. The dominant trees are the microspecies of the sessile oak group (Querem petraea agg.), mainly the lanceolate leaved Quercus dalechampii and the turkey oak (Q. cerris) with the silver lime {Tilia tomentosa). In the lower canopy the scattered occurrence of Sorbus torminalis is characteristic. The shrub layer is much less developed than in the top-forest, although its cover (20-75%) and height (1-4 m) varies within a rather broad range. Cornus mas, Euonymus verrucosus and Rosa arvensis play a considerable role. Lonicera caprifolium is only an accidentally occurring element, although sometimes with high cover value. In the herb layer of high cover values (50-90%) Brachypodium sylvaticum, Dactylis polygama, Melica uniflora, Poa nemoralis, Doronicum orientale and Festuca heterophylla may be dominant. The elements of the xerophilous grassland (Festuco-Brometea, Festucetalia valesiacae) play a restricted role and the frequency of the thermoxerophilous hairy oak forest elements (Quercetalia pubescentis-petraeae, Orno- Cotinetalia, Quercetalia cerris, Quercion farnetto etc.) is lessening considerably, and more or less the same as in the top-forest. In contrast, the plants of the mesophilous forests (Fagetalia, Carpino-Fagetea) are represented in an increasing ratio, although with less abundance than in the top-forest. The most important differential species against the top-forest are: Ajuga reptans, Carpinus betulus, Cerasus avium, Clinopodium vulgare, Galium mollugo, G. schultesii, Festuca heterophylla, Hieracium sabaudum, Lapsana communis, Lathyrus niger, Fuzula forsteri, Poa nemoralis, Potentilla micrantha (characteristic species!), Prunus spinosa, Quercus petraea agg., mostly Q. dalechampii, Sileneviridiflora, Veronica chamaedrys (see Tables 2 and 6-10). Rock-forest (Tilio tomentosae-Fraxinetum orni (Horvát 1958) Soó et Borhidi in Soó 1962) It grows on the steep rocky northern slopes of cool and humid microclimate. The ecotop is similar to that of the top-forest, to a certain degree, because of its shallow, rendzina-like rocky soil. Its canopy is less closed (60-80%) but considerably higher (16-28 m) than those of the top-forest. The characteristic trees are the Acer platanoides, A. pseudoplatanus, Tilia platyphyllos and T. tomentosa mostly Acta Bot. Hung. 41, 1998