Kovács I. (szerk.): A Magyar Természettudományi Múzeum évkönyve 78. (Budapest 1986)
Szujkó-Lacza, J. ; Rajczy, M.: Similarity investigations on a loess steppe fragment in a forest-steppe in Hungary
Methods The forest "Kerecsendi berek erdő" is situated south of the Bükk mountains, near to highway E-96, in N-Hungary. This forest had been used for hunting for at least four centuries. The main forest track cutting through it (NW-SE in a direction) has not been moved during this time according to the records. The steppe fragment lies on this road where it comes up from a valley to a small plain ground and widens out to 7 meters (and then narrows to 5 meters again). During the year 1981, from 3rd April, we collected and recorded the species in the forest (Aceri tatarico-Quercetum ), at the edge of this forest and on the forest tracks at approximately fortnight by intervals (the specimens are deposited in the Herbarium of the BotanicalDepartment of the Hungarian Natural History Museum, Budapest). On 31st June 1981 we recorded the floristic composition of the steppe fragment. The forest track was divided to two-meters long relevés. The estimated cover values were recorded in percentages. The data are given in Table 1. Below Table 1 there is a list of species which occurred in the relevés in spring but at the time of the recording they were in an unidentifiable stage. The N W extremity of the relevé series was indicated by number 1. This part of the relevé series is the nearest to the valley and it is accompanied by a forest fragment of Polygonato (latifolii)-Quercetum situated in that valley. The other relevés are connected with the forest Aceri tatarico-Quercetum. Diversity of relevés was calculated from the data of cover % per species (H^^) and that of the species from the data of cover % per relevés ("covering diversity", H" Q cf. DOBOLYI et al. 1981) by means of the Shannon formula (SHANNON 1949) with a logarithm base to 2. Evenness was calculated as H"/log 2 s, where s was the number of attributes (cf. PIELOU 1975). The process of changing of the diversity of the relevés as a trend was analysed by the DIVDROP method. With the aid of this method one can estimate the importance of the species in shaping the great changes in the value of diversity (RAJCZY & PADISÁK 1983). Similarity between every relevé pair was calculated with help of the similarity functions of JACCARD (1901), CZEKANOWSKI (1909), HORN (1966) and HUMMON (1974). Average linkage cluster analysis was carried out using the WPGMA fusion algorithm (SNEATH & SOKAL 1973). The clusters formed by the analysis were analysed using the RISE method. By means of this method one can identify the species being the most importantin forming the certain cluster (HAJDU & RAJCZY 1982). The computations were carried out on the CDC 3300 computer of the Hungarian Academy of Sciences using the BP program package of the Hungarian Natural History Museum. Results and discussion We recorded 82 species in the 20 relevés on 31st June. Considering the species collected here earlier, there were altogether 114 species found in this spot. Eighteen species occurred only in the first 5-6 relevés (NW side of the relevé series), namely Artemisia pontica, Arrhenatherum elatius, Asperula glanca, Briza media, Cytisus nigricans, Hypericum perforatum, Hypochoeris maculata, Knautia arvensis, Koeleria cristata, Phlomis tuberosa, Picris hieracioides, Plantago lanceolata, Polygala comosa, Serratula tinctoria, Silene nutans, Thymuspulegoides, Vincetoxicum hirundinaria, Viscaria vulgaris. Six species grew only in the SE side of the relevé series, Galium cruciata, Lithospermum arvense, Nepeta pannonica, Peucedanum oreoselinum, Prunella laciniata and Torilis anthriscus. Considering the plant species collected or recorded by us, we established the common species in the f our habitat, namely the steppe fragment ; the f orest (Aceri tatarico-Quercetum ) ; the edge of this forest; the other (narrower) forest tracks. The narrower forest tracks and the steppe fragment have 44 species in common (Table 2.); the steppe fragment and the edge of the forest have 26 (Table 3.). It can be stated that these species represent the "forest-steppe element" in our steppe fragment (only 8 of them are "forest-steppe species" as according to ZÓLYOMI (1958). The common species in other combinations of habitats are also given in Table 3. There are two species common to all of the 4 habitats, Chrysanthemum corymbosum and Vincetoxicum hirundinaria. It can be seen this way that the steppe fragment has 51 species occurring only there, on the widened part of the main forest track.
