Zs. K. Komáromy szerk.: Studia Botanica Hungarica 17. 1984 (Budapest, 1984)

Szerdahelyi, Tibor: Rare ferns of Hungary III. The establishment of fern species in a planted pine forest

islands. These include about 10-40 ferns and their area is about 1-3 square metres. Probably the common species became first established and later followed them the rare species. I have observed that the moss carpet retires, at several places disappears under the fern groups.The Polystichum individuals occur almost under the Dryopteris filix-mas groups, in the places rich in moisture content and poorly illuminated. The reason for this could be the deficiency in optimal light intensity. So the formation and development of the moss and fern patches change with time and space. When this state of dynamic equilibrium was reached, the fern composition became the richest in species. dianges came after damage by Fomes annosus greatly increased. This incurred the drying of the trees and finally the thinning of the forest. As a consequence of this the tree stratum opened up, the grass layer became richer in species than some years previously. Several species of weeds became established and this put an end to the spread of the ferns. In the last two years I observed that weed species tried to invade the grass layer. The weeds compete for the free places now. This condition is instable as it changes every year. Nevertheless it is worth while to try to characterize the role of the fern groups in the grass layer of the forest. The purpose of this study is to search into the causes of the establishment of the ferns. MATERIAL AND METHOD The cenological investigations were carried out in July 1982. Fifty 2 by 2 m sample plots were taken. Cover values according to the BRAUN-BLANQUET scale were assigned to the species (Table). On Figure 1 we indicated the distribution of the sample plots in ' Ebgondolta' forest. The sample plots were taken from places where the fern groups were in the thickest part of the forest. The distributions of the floral elements in the species list and the ecological indexes are depicted in Fig. 2. These are: R (soil requirement), T (temperature requirement), F (water requirement) and N (nitrogen requirement). These ecological indexes are plotted against percentile relative contribution of the group to total counts. The data of the sample plots were clustered by a computer programme, using three functions, namely Jaccard's, Czekanowski'

s and Hummon'

s (see the dendrogram of Czekanowski'

s index in Figure 3). Table 1. Species and their cover values in sample plots Samples Species 1-10 11 - 20 21 - 30 31 40 41 - 50 Achillea sp. + + + + Agrostis alba 3 2 + + 2 + Agropyron intermedium 21 + 2 Agropyron repens 1 + + 22 Asplenium ad

. -nigrum ++ + + +1 1 + + Asparagus officinalis + Asplenium trichomanes + ++1 1+4 1 ++ ++ Astragalus glycyphyllus + Athyrium filix-femina 2 Atriplex patula ++++ ++ + + + Berberis vulgaris 2 + Brachypodium pinnatum 1 4 Brachypodium silvaticum 2 11 421 1 +2 +21+2 + + 1 + 12+2 Bromus ramosus + + Bromus sterilis 1 Calamagrostis epigeios + Cannabis sativa + Carpinus betulus + Carex hirta 1 5 Carex pairei + Carlina vulgaris + Celtis occidentalis + Cerastium brachypetalum + + +++++ + ++ +