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• Data on the pioneer vegetation of the Lake Velence

  203–208

  Norbert Riezing

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  235

  Lake Velence is one of Hungary's largest saline lakes. Part of its natural dynamics is that certain parts of the lake bed regularly dry out, providing pioneer surfaces suitable for the emergence of plants of the mudflats and drying (saline) ponds. During the particularly dry year of 2022, the water level was per­manently and significantly low, allowing to study the vegetation of the dry lake bed. In the first half of the last century, the natural vegetation of the lakeshore (including salt steppes) was studied, but there are very few records of the pioneer species of the lake bed. The salt steppes around the lake have now largely declined, but due to low water levels, some of their characteristic species are still present in the lake bed (though, usually in low number of individuals). Examples include Crypsis aculeata, Cyperus pannonicus, Suaeda pannonica, the once abundant Suaeda prostrata, and the previously rare Crypsis schoenoides and Spergularia salina. Spergularia maritima was once widespread but currently not found in the lake bed. Although, Schoenoplectus litoralis is not a member of the ephemeral vegetation, but is a characteristic plant of the littoral zone of Lake Velence. This species probably appeared therein the middle of the last century and is currently spreading.

• Contributions to the flora of the Danube River in Komárom-Esztergom and Fejér counties (Hungary)

  157–168

  Norbert Riezing

  Views:

  289

  The present paper focuses on the aquatic and Nanocyperion vegetation of the Danube flood­plain. Most of the data show the results of the surveys in 2019 at low water levels. The Nanocyperion and aquatic vegetation of the Komárom-Esztergom County section is relatively well researched com­pared to the Fejér County section which was previously poorly known. In the last decade, two rare spe­cies – Hippuris vulgaris and Hydrocharis morsus-ranae – have disappeared between Gönyű and Neszmély (Komárom-Esztergom County). In contrast, several new invasive plants have appeared: Salvinia molesta, Myriophyllum aquaticum, Limnobium laevigatum, and Crassula helmsii (first record from Hungary). Vallisneria spiralis and Elodea canadensis were detected again after several decades. Elodea nuttallii and Azolla sp. have become more widespread and abundant than previously. New and uncommon Nanocyperion species were the native and protected Lindernia procumbens and the inva­sive Lindernia dubia. New invasive plants in the studied Danube sections were: Cyperus esculentus, Euphorbia maculata, and Eleusine indica. The native Veronica catenata and Schoenoplectus triqueter have become more wide­spread than before. Polygonum graminifolium was an interesting find of open pebble surfaces in several parts of the examined area, which has no recent records in Hungary from before 2015 (published here).