Szekessy Vilmos (szerk.): A Magyar Természettudományi Múzeum évkönyve 55. (Budapest 1963)
Halász-Halmi, M.: Microphyto-sociology of the acrothermal springs at Harkány and at Budapest - Mt. Gellért
microph yto-sociology of the agrothermal springs The algal layer is 1—4 mm thick. In this zone, Symploca thermalis loses its strong dominance gained in zone V, though its covering grade is still 4 at the inner edge of the zone, but, as we progress with our observations towards the outer edge of the zone, we find that its covering percentage gradually decreases to grade 2 at the outer end. The dominance in this zone is taken gradually over by Schizothrix calcicola , and though its covering percentage at the inner edge is only degree 3, it increases gradually towards the outer edge where, in many places, it reaches degree 5. Together with the two dominants, we find again some accompanying species, e. g., Gloeocapsa gelatinosa, Gloeocapsa arenaria, Phormidium orientale, Phormidium fragile, and a number of others, yet only sporadically, or with the covering degrees 1—2. Also Hapalosiphon laminosus appears, yet only here and there and mostly as fragments of its filaments. We designate the association of the last zone as Symploceto-Schizothricetum ealcieolae. Vertical Wall. This wall has five zones, but the two lowest zones were washed away by the rush of the spring water, while the fifth zone — having abundant place on the wall for extending — developed in its upper part above the level of the upper brim of the semicircular side, thus emerging partly from the constantly vaporous atmosphere of the basin, and became also exposed to the effects of the outer atmosphere. The microvegetation on this wall is essentially similar to that of the semicircular wall, but there are also strong differences. The two lowest zones had probably pure Hapalosiphon laminosus associations during the past decades, but since they had been washed away we can no more explore the sociological construction at the present. The temperature of the surrounding atmosphere in this area varies between 54—42 centigrades. Zone III has a surrounding atmosphere of' temperatures fluctuating between 42—38 centigrades; the algal layer is 1—3 mm thick. The analysis of the „MinimiAreal" shows that Symploca thermalis has the strongest dominace with a covering grade of 3, in this zone, but Hapalosiphon laminosus is equally strong in many parts of the zone, especially on the lower edge where its covering grade is 3. When proceeding towards the higher edge of the zone, its abundance gradually decreases to grade 2, sometimes even to 1. The accompanying species of the two dominants are the same as on the opposite side of the basin in zone IV. Thus the association of this zone is to be named as SymplocetoHapalosiphonetum laminosi. Zone IV. The temperature of the surrounding atmosphere is 34—32 centigrades; the thickness of the layer 0,5—3 mm. The sociological investigation shows the dominance of two species: Symploca thermalis (occuring abundantly also in the former zone), and Schizothrix calcicola. Both species have a covering grade 3. The accompanying species are Aphanocapsa thermalis, Oscillatoria angustissima, Phormidium fragile, but they are sporadic, reaching only sometimes grade 1. We name this association Symploceto-Schizothricetum ealcieolae. Zone V. The temperature of the surrounding atmosphere decreases from 34 to 32 centigrades, as the upper part of the zone, emerging from the more closed atmosphere of the basin, is partly exposed to the influence of the external air. The algal layer is 1,5—3 mm thick. In this cooler atmosphere, Gloeocapsa gelatinosa appears with a stronger abundance, and gains dominance in the zone, together with Schizothrix calcicola. Both species have a covering grade of 3—4. Gloeocapsa gelatinosa has a stronger abundance in the upper parts of the 11*
