Zs. K. Komáromy szerk.: Studia Botanica Hungarica 17. 1984 (Budapest, 1984)

Siklósi, Engelbert: The flora of the pits in the Nature Preservation Area of Ócsa

Diversity is more noticable in the reed-grass vegetation than in the riparian vegetation.Utricularia, Ceratophyllum, Myriophyllum and Potamogeton species do not occur in the reed-grass of the canal. The reason for these différencies is probably the thick mud layer and the presence of rich nutritive material. In lakes 3 and 5 the Phragmition communis association is completely absent in contrast with the lakes mentioned above. Furthermore, these lakes are considerably poorer in species than lakes 1 and 2, regarding their coastal and reed-grass vegetation, too. The steep shore and the sudden drop could cause this kind of appearance of the riparian vegetation. Utricularia species are absent, but I found Potamogeton pect

inatus and Potamogeton perfoliatus. We can explain this by the dissimilar ages of the lakes. Lakes 3, 4 and 5 are the youngest, so they are only slightly filled up.The beaches show the characteristic features of artificial origin. It has been found that the previos boggy association will step by step be re-established. Unfortunately the rarest, most valuable species are absent from these associations. We think that the reintroduction of these species to areas of previous occurrence would solve the problem. So the vegetation completely changed and inpoverished by turf-pit will become similar to the one of the original associations. REFERENCES BOROS, Á. (1952): A Duna-Tisza köze növényföldrajza. [Geobotany of the territory between Danube and Tisza]. - Földr. Ért. 1: 39-53 p. BUZETSZKY Gy. & ZSUFFA, I. (1979): A Duna-Tisza köze vizrajzi viszonyai. [Hydrography of the territory between Danube and Tisza.] - In: TOTH, K. (ed.) Nemzeti Park a Kiskunságban. [National Park in the Kiskunság], Natura, Budapest, 519 pp. IVÁNYOSI, A. (1979): A Duna-Tisza köze felszine. [The surface of the territory between Danube and Tisza.] - In: TOTH, K. (ed.): Nemzeti Park a Kiskunságban. [National Park in the Kiskunság.] , Natura, Budapest, 519 pp. SOÓ, R. (1964-1973): A magyar flóra és vegetáció rendszertani-növényföldrajzi kézikönyve I.-V. (Synopsis systematico-geobotanico florae vegetationisque Hungáriáé I.-V.) - Akadémiai Kiadó, Budapest (1964): 519 pp., (1966): 655 pp., (1968): 506 pp., (1970): 614 pp., (1973): 723 pp. SOÓ, R. & KÁRPÁTI, Z. (1968): Növényhatározó II. [Plant Identification Handbook.] - Tankönyvkiadó, Budapest, 846 pp. SZABOLCS, I. (1979): A nemzeti park talajviszonyai. [Soils of the National Park.] - In: Tóth.K. (ed.): Nemzeti Park a Kiskunságban. [National Park in the Kiskunság.] Natura, Budapest, 519 pp. Author's address: E. SIKLÓSI National Authority for Environment Protection and Nature Conservation Budapest, Szépvölgyi street 162. H-1025 HUNGARY