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• The degradation of hygrophilous plant associations of the Nyárjas Lake (E Hungary)

  63–77

  Mihály Vas

  Views:

  131

  The Nyárjas Lake (located near Kállósemjén, East Hungary) was one of the most typical bogs in the Nyírség until the early 1980’s. Most of its area was covered by the association of Carici-Menyanthetum. The number of species characteristic to the mentioned association was generally high. As the climate became drier, hotter and were characterised by higher magnitude of extremities, the water coverage became no longer as permanent. This resulted that the Menyanthes trifoliata and Listera ovata became extinct by 2000. Lemno-Potamea species were not found after 2010. Bidentetalia, Calystegietalia, Chenopodietea and Secalietea species became more prevalent, particularly in drier periods, and locations where Carici-Menyanthetum used to be characteristic. Cirsium arvense in the mid-1990’s and that of Urtica dioica in the mid-2010’s became dramatically abundant. Both the number and coverage of species indicating habitat degradation have increased. The composition of wet meadow plant associations shifted towards the drier Arrhenatheretea. A moderate revitalisation of wetland associations was, however, observed coinciding years with higher precipitation.

• Black poplar riparian forests (Carduo crispi-Populetum nigrae) along the river Drava

  215–238

  Balázs Kevey

  Sándor Csete

  Views:

  191

  The objective of this study is to analyse the phytosociological characteristics of riverside black poplar forests on the flood plain of the Drava River (southwestern Hungary) by means of 25 relevés. Based on the results of traditional analyses (vegetation structure and attributes of constituent species), their ecological niche and place in plant succession, those streamside forests can be identified with the plant association Carduo crispi-Populetum nigrae described from the Szigetköz region (northwestern Hungary). Stands of this association develop from purple willow scrubs (Rumici crispi-Salicetum purpureae), and are located at an elevation about one and a half meters lower than those of its successor vegetation unit, the white poplar association (Senecioni sarracenici-Populetum albae).

• Contributions to the algal flora of a recently-formed peat moss bog near Kőszeg (W Hungary)

  113–130

  Sándor Bancsó

  Views:

  388

  The Alsó-erdő peat bog near Kőszeg has undergone a significant transformation since its first mention in the literature. In addition to the original single patch, a smaller one appeared a few decades later. The process did not stop and a third unit, discussed here, was formed. The succession of its macrovegetation towards the typical peat moss association started slowly but surely, due to balanced water regime and other optimal environmental conditions. The process is more advanced for the algal vegetation, which shows the characteristics of peat bogs already. The high species diversity found makes the habitat highly valuable itself. Although a special, unique algal species has not been found in previous studies, 27 Desmidiales taxa listed as endangered occur sometimes with high density and make the habitat even more valuable. Based on our results, the area deserves special attention both from the habitat conservation and research point of view. At the same time, its further monitoring can provide crucial information for exploring and understanding the succession of similar habitats, and thereby for their more efficient protection.