B. Papp szerk.: Studia Botanica Hungarica 37. 2006 (Budapest, 2006)

Bauer, Norbert: Open sandy grasslands of the Bakony region

picture of a plant association system combining the author's own and published relevés. MATERIALS AND METHODS The Bakony region (administrative Hungarian landscape-geographical name: Bakonyvidék) is the largest mesoregion of the Transdanubian Mountains. It includes the Keszthely Mountains, the Tapolca Basin, the Balaton Uplands, the southern and northern Bakony, and the Bakonyalja (ÁDÁM et al. 1988). Significant surface sandy occurrences can be found at the Bakonyalja, on the western margin of southern Bakony, in the Tapolca Basin and in the basins of the Balaton Uplands (mainly in the Kál Basin) (BENCE etal. 1990, BUDAI et al. 1999). At foothill areas of the mountains sand beds of various size can be found around the territory of the supposed abrasion platforms of the Pannonian Sea from the Mio-Pliocene (Pannonian) period. In the Bakony the erosion of thickly piled up pebbles, sand and clay cover was already in progress, taking place parallel with the uplift of the area, which process also continued in the Pleistocene. The erosion contributed to the formation of the piedmont sand and pebble nappe in a complex way, and during the drier climate periods these surfaces continued to change through the process of deflation. These sandy substrates, sand beds have a varied lime content, which may be attributed to the lithological variety of the nearby eroded areas made up of Triassic dolomite, Triassic, Cretaceous period, Eocene limestones, pebble, conglomerate, etc. In addition, certain changes have occurred as post-effects (leaching, lime-concretion in different layers, exsurgences). The present paper publishes relevés of open grassland stands from around Fenyőfő, Bakonyszentlászló, Bakonyszücs on the Bakonyalja (sandy surfaces of varied lime content), from the areas near Nagytevel (limeless sandy surfaces), near Hegyesd, Sáska, Sümeg in the southern Bakony and near Salföld and Szentbékkálla in the Balaton Uplands (limeless silica sand surfaces) (Fig. 1, Table 1 ). The vegetation was sampled with the BRAUN-BLANQUET (1964) quadrate method (using 2 m x 2 m quadrates). Altogether, 85 coenological relevés representing the Bakony region (Tables 2-5) are published here. Nomenclature of the plant names follows SIMON (2000); JÄGER and WERNER (2002) in the case of species native outside Hungary; ERZBERGER and PAPP (2004) for the bryophytes; (SIMON 1991) for the lichen taxa; and BORHIDI (2003) for the plant association. The statistical analyses were performed with SYN-TAX 2000 (PODANI 2001) programme package. Published samples of a few previously described units were used for the comparative evaluation of relevés: BORHIDI (1956) "Festucetum vaginatae arrabonicum \ "Festuceto-Corynephoretum arrabonicum". Because of the quadrate size was different from ours, these were considered as presence-absence matrix analyses. Of the results of the performed multivariate statistical analyses we present two diagrams: (1) the results of the principal coordinates analysis (PCoA) containing our samples [matrix containing AD values] (Fig. 2), and (2) showing the principal component analysis (PCA) based on a presence-absence matrix including our samples and those of BORHIDI from Fenyőfő and Bakonyszentlászló (Fig. 3). By analysing the binary matrix our objective was to avoid that the higher AD values of some dominant species make unwanted influence on the results, and that the actual differences of species composition do not determine the ordination. While describing the stands of separating units we also considered the conclusion of the PCA diagram biplot representation.