Ábrahám Levente: Biomonitoring a Dráva folyó magyarországi szakasza mentén 2000-2004 - Natura Somogyiensis 7. (Kaposvár, 2005)

Juhász, Magdolna - Lóki, József: Changes of surface area of assimilating leaves - Asszimiláló levélfelületek változásainak vizsgálata

Natura Somogyiensis 7 19-23 Kaposvár, 2005 Changes of surface area of assimilating leaves JUHÁSZ MAGDOLNA

1 & LÓKI JÓZSEF

2 Somogy County Museum Natural History Department, H-7401 Kaposvár, Fő u. 10., Hungary, e-mail: juhasz@smmi.hu 2

University of Debrecen Department of Physical Geography and Geoinformatics, H-4010 Debrecen, P.O.B.9., Hungary, e-mail: jloki@delfin.unideb.hu JUHÁSZ, M., LÓKI, J.: Changes of surface area of assimilating leaves. Abstract: Physiological state of dominant tree species of temporarily flooded alluvial forests was studied by measuring changes of assimilating surface area. A significant correlation between leaf size and water supply of the growing place was pointed out. Strongest connection with water level changes of the river was shown by changes of assimilation surface of Salix alba, living in the low floodplain. Key words: biomonitoring, alluvial forests, leaf assimilation area Introduction Changes of assimilation area of leaves were studied within the scope of biomonitoring of alluvial forests along the river Dráva (JUHÁSZ 1997, 2004, JUHÁSZ & DÉNES 2001, 2004, MARKO & JUHÁSZ 1997). These studies are part of a complex environmental monitoring system, started in 2000, aiming to monitor environmental effects of a hydroelectric power plant - planned on the river Drava in Croatia - in Hungary. Existence, species compositon and other characteristics of plant communities living in floodplains are strongly dependent - through water supply of their growing place - on water level changes of the river. The assimilation surface area of leaves is a sensitive indicator of water supply of the growing place. Plants with high water demand are especially sensitive from this point of view, this is why we measured changes of assimilation surface area of leaves of dominant trees of alluvial forest communities temporarily flooded. Materials and methods For measuring changes of assimilation surface area of tree leaves study material is collected exactly on the same plots every year in autumn after falling of the leaves. On every plot 200 leaves were collected randomly. Leaf area is determined by an informatical method (LÓKI 1996) because we have no financial means to obtain a laboratory equipment for this purpose. Essence of the method: collected leaves (200 pes per plot) are prepared as usual for herbariums (dried