L. Lőkös szerk.: Studia Botanica Hungarica 25. 1994 (Budapest, 1994)

Szerdahelyi, Tibor: Gallery forest fragments in the Szigetköz Protected Area (Hungary)

Studia bot. hung. 25, pp. 59-75, 1994 GALLERY FOREST FRAGMENTS IN THE SZIGETKÖZ PROTECTED AREA (HUNGARY) T. SZERDAHELYI Department of Botany, Hungarian Natural History Museum H-l

476 Budapest, Pf: 222, Hungary This work contains the coenological investigations of 4 gallery forest fragments (Querco-Ulmeto pannonicum) of the Szigetköz Protected Area. At four sites 76 sample plots were examined and compared according to their floristic composition, ecological parameters (TWR-values) and coenological characters. By using cluster analysis and principal coordinate analysis 7 sample groups could be identified. The phytosociological evaluation of these groups are discussed. Key words: vascular plants, coenology, cluster analysis, gallery forest fragments, Szigetköz INTRODUCTION The investigations were carried out within the frame of an Academic Research Fund (AKA) in 1991-92. We tried to fix the present conditions of the selected plant associations before the expected influences because of the river Danube diversion. Because of the planned water power station (in Slovakia at Gabcikovo) the main Danube, the lateral Mosoni-Duna branch and other branches share considerably less water per seconds than previously. Since the power station has built (1992) and great quantity of the water output of border Danube goes to an artificial channel to the power station in Slovakia, only the rest of water comes to Hungary and flows through the Mosoni-Duna or other lateral branches that is about 1/3-1/4 of the former water output. As a result, the area of Szigetköz will undoubtedly dry out. MATERIALS AND METHODS By using 10 by 10 m quadrats 76 phytosociological samples were taken at four sites according to the Braun-Blanquet method (BRAUN-BLANQUET 1964). The first site was the "Derék-erdő", the second was the area beside village "Feketeerdő", the third was a little fragment near village "Ásványráró" and the last one the "Lóvári-erdő" close to Rajka. Probably these stands were internal parts of an extent contiguous forest existing before. Because of the intensive agriculture and the forest and wild farming the unbroken stand was fragmented, the natural forest Studia Botanica Hungarica 25, 1994 Hungarian Natural History Museum, Budapest