Kaszab Zoltán (szerk.): A Magyar Természettudományi Múzeum évkönyve 77. (Budapest 1985)

P. Komáromy, Zs.: The role of algal synusia of grasslands in successional process in Hungary

grass-steppe alkali flat zone Fig. 1. The occurrence of algal species in the quadrat on solonetz soil Samples from the soil algal synusia were obtained from 5 X 5 m quadrats, consisted of twentyfive 1 m square quadrats. Samples were taken from the alkali flats, halophyte grass communities and from the transitional zone between the two. Four or six algal species occurred in the samples of open grass communities (Artemisio-Festucetum pseudovinae). A great variability of the species was observed in the alkali flats (Puccinellietum limosae or Camphorosmetum attnuae community). Empty quadrats alternated with samples containing rich algal flora (8-10 species) as a consequence of the different water conditions of the sampled micro-areas. The soils of the grassy communities, situated on higher ground, possess good water conditions, while the alkali flats are flooded with water in spring. During summer the higher areas gradually dry up, but there are wet patches on the alkali flats with enough water for the algae. The other places are absolutely dry. It is evident, that species richness is the highest in the places of favourable water conditions of longer periods (Fig. 1). The algal crusts also exist in dry conditions so the binding soil particles are protected by them from the heavy summer rains and persistent winds. In addition, they contribute to the succession by the settlement of mosses, lichens and flowering plants in the algal crusts. Erosion is therefore even less. The most frequent soilbinding algal species were on alkali soils in Hungary: Phormidium foveolarum, Phormidium paulsenianum, Calothrix elenkinii, Nostoc commune, Phormidium papyraceum and Lyngbya mucicola (in decreasing order of frequency). Various zones of plant communities occurred on the shores of the astatic salt lakes. More than a hundred algal species were identified from the examined saline waters (Kiss 1975). At the margin of saline water the species number decreased rapidly (KOMÁROMY 1980), the characteristic plankton species disappeared and some blue-green algae and diatoms occurred. The species composition of the soil algal synusia and the percentage of various algal phyla is apparently constant in the wet mud (Fig. 2). But the spatial pattern