B. Papp szerk.: Studia Botanica Hungarica 35. 2004 (Budapest, 2004)

Szollát, György; Schmotzer, András: Contributions to the flora and vegetation of the environs of Balassagyarmat (Hungary)

ignated with the locality names Balassagyarmat, Ipolyszög and Ipolyszög-Újkóvár, are within the borders of our area surveyed. Valuable recent data have been accumulated by Imre Nagy, a biology teacher and naturalist knowledgeable of the area. He lists several species from the Ipolyszögi Egerláp disappeared recently (NAGY 1994) (see Table 1). As summarised by him, in the middle of the 80s alarming changes occurred in the area. Important euhydrophyte habitats have been destroyed, dried-out reed beds and those of large sedges had been overgrown by weeds, the fens and meadows have become willow mire woodlands, and although the alder swamp woodland still stands, it started to dry out and shows disadvantageous changes in its vegetation. Floristical data provided by Miklós Csapó (CSAPÓ 1978) partly correspond with those of Nagy. Recently, two environmental studies made by the ÖKO Rt. Corporation (based in Budapest, I. Attila út 16) dealt with the surroundings of Balassagyarmat (GERGELY et al. 1994, RATH et al 1994). The relevés published in these studies evaluating the former changes in the environmental circumstances of the Ipoly river and in the area influenced by it, include floristical data from the alder swamp woodlands of the Ipolyszögi Egerláp and from the dry grasslands nearby. Although these contain valuable floristical data, they have no phytosociological merit because of the lack of cover values and table headings. Of the most recent data it should be highlighted that Dryopteris dilatata was found at site No. 11 by Gergely Király and János Bölöni in 1997 (in FARKAS 1999). All floristical data of the publications mentioned above are listed in Table 1. METHODS OF SURVEY AND ANALYSIS The majority of the surveyed area (Fig. 1 ) is almost flat, the elevation is about 140 m. This area belongs to the Middle Ipoly valley, which is part of the Balassagyarmat basin microregion in the Nógrád basin mesoregion. The remaining parts, basically lying around the upper and middle reaches of the Nyirjes stream are somewhat hilly. The elevations vary between 180 m (at the Nyirjes stream sources, at the southeastern end of site No. 6 and at the southern end of site No. 7) and 140 m further down. In larger geographical scale, this area is part of the Northern Cserhát microregion in the Cserhátvidék mesoregion. The parent material is mostly alluvial deposit (river gravel, sand and clayey drift) and loess, respectively. The Ipolyszögi Egerláp, comprising about 100 hectares, was declared as a local (county level) nature conservation area in 1975, and later by the municipality of the town of Balassagyarmat in 1990. Seven years later it became part of the then established Duna-Ipoly National Park. The majority of the Nyirjes stream catchment area and its surroundings are also protected by the decrees of the municipality, just like certain parts of the flood plains of the Ipoly river including even areas of stagnant water (Fig. 1).