Zs. P. Komáromy szerk.: Studia Botanica Hungarica 13. 1979 (Budapest, 1979)

Szerdahelyi, Tibor: Rare ferns of Hungary, I. Botrychium virginianum (L.) Sw. var. europeum Angstr. in the Kiskunság National Park

In 1978, we began to examine the coenological conditions of B. virginia num

. We are trying to establish to what extent the acacia plantations have changed the ecological conditions of the original plant association and whether the changes have not endangered the survival of B .virginianum

. MATERIAL AND METHOD - Coenological samples were taken in the habitat of B. virginianum

, in 2 x 5 continuous squares of 2 x 2 m, with special regard to the fact that the plant occurs in special microrelief. This means B. virginianum is to be found in shallow flat basins and in ditches. The uptake values of the cenological samples were determined on the basis of estimation and expressed in percentages. For recording the developmental conditions a decimal code-system was applied (cf. SZUJKÓ-LACZAFEKETE 1973) in which the phenological stages were expressed by appropriate decimal symbols (the stage of rest is 10, vegetative stage is 20, generative 30, disorganized is 40). The phenophases occurring within the developmental conditions are expressed by the first-place numbers. This phenological codesystem has already been prepared earlier for phanerogams and cryptogams as well, with the exception of Pteridophyta (SZUJKÓ-LACZA, KOVÁT S

, ORBÁN, P.VERSEGHY, P. KOMÁROMY, HAJDÚ 1976). The estimated diversity index (H') values according to species and samples of the coverage were calculated by the formula of SHANNON-WEAVER (1948), while the smoothness (J) by that of PIELOU (1975). RESULTS AND CONCLUSIONS - The decimal codes elaborated for ferns are summarized in Table 1. The species list, compiled on the basis of the coenological samples, given in Table 2. From this table it can be reconstructed that the original association was Convallario-Quercetum danubiale

. The canopy level today is mainly composed of Robinia pseudo-acacia which has been planted artificially. Thus, B. virginianum is mainly found in Bromo steriliRobinietum

. The appearance of this species has brought about the changing of the undergrowth everywhere in the original community. Robinia pseudo-acacias associate most frequently and in mass with Bro- mus sterilis

, and its disturbance is indicated by the presence of a number of weed species, as for example Ballota nigra

, Sambucus nigra

, Galium aparine

, and Cerastium sp. The members of the original plant community: Quercus robur

, Cratae gus monogyna

, Ligustrum vulgare

, Berberis vulgaris

, Rhamnus catharticus

. Ulmus procera

. At the grass level: Viola cyanea

, Geum urbanum

, Bo try chium virginianum

, Thalictrum minus

, Brachipodium silvaticum (SOO 1964). In Table 2, in addition to the species list, the phenophases and also the frequency rate of species occurrences in the ten coenological samples are to be found. In Table 5, the species are enumerated in the decreasing order of their occurring together. It can be seen that the four species in every case occur together with B. virginianum

. Of the species of Convallario-Quercetum association, B. virginianum was found together with Viola cyanea and Geum urbanum in four cases.