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)

are represented by only a few species, although some of them being frequent (e.g. Aegopodium podagraria, Brachypodium sylvaticum, Circaea lutetiana, Geum urbanum, Glechoma hederacea, Heracleum sphondylium, Lamium macidatum, Veronica chamaedrys). Site Nos 6-11 The plant communities that follow the Nyirjes stream and those situated in its lower reaches (Ipolyszögi Égerláp) are in close connection with each other. The water supply of the Ipolyszögi Égerláp is not only provided by the stream, but also by the groundwater of the river terrace, nurtured by local warm springs (and - to some extent - from the occasional floods of the Ipoly river). However, water engineering causes obvious drying in the area and as the process of degradation continues the once native vegetation is unable to function properly in the ecosystem. Human (water engineering) activity started almost a hundred years ago by 1) digging draining ditches within the territory of the Ipolyszögi Égerláp, later 2) damming up the water of the Nyirjes stream, 3) deepening the bed of the stream at the middle reaches below the ponded back fish-stews, 4) canalisation of the riverway of the Ipoly river in 1968 and 5) the deepening of the river bed by about 2 metres afterwards. On top of these, the floods pass down quickly and, consequently, the groundwater table of the nearby areas has been sinking gradually. The development of the road and railway systems has also contributed to the drying out of the area, since the alder swamp woodlands of the Ipolyszögi Égerláp had been locked within banks. The upper and middle reaches of the Nyirjes stream are lined by submontane stream ash-alder woodlands, gradually replaced in the lower reaches by alder swamp woodlands. (The degraded vegetation in the close proximity of the fish ponds was not studied in detail; those plant communities vary by locations and contain only the most common swamp plants, reed beds, etc.). Site No. 6 Elevation: 165-180 m. One of the arms of the Nyirjes stream, coming from southeast, is running in a small valley bordered with gentle slopes. The flat bottom of the valley is relatively narrow, varying from about 3 to 10 metres across, and its water supply partly comes from very small springs oozing from the side in several spots (one of them is the Segítő Szűz Mária spring). The stream ash-alder wood (Aegopodio-Alnetum V. Kárpáti, I. Kárpáti et Jurko 1961) lining the streamlet is