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
20 NATURA SOMOGYIENSIS between blotting papers, under light pressure) for about three weeks, then fastened on white paper and scanned. Assimilation area is determined through measuring leaf surface area. Files are prepared by software Paint Shop Pro for GIS processing. Every leaf area is measured by software IDRISI, average leaf area per plots will be determined by Microsoft Excel. Results For measuring of assimilation surface area of leaves material is collected at four plots. Characteristic dominant tree species of low floodplain forests along the Drava is Salix alba; its leaves are collected at three plots. First plot is upstreams of the planned power plant (near village Őrtilos), second one is upstreams of the mouth of the lower canal of the planned power plant (near village Bélavár), and third one is downstreams of it (near village Vízvár). Fourth study plot is situated on the wide lowland plain beside the planned power plant, near village Gyékényes; here tree species Alnus glutinosa is studied. Research has begun in 2000; here we publish results of five study years (Table 1). Table 1.: Measured data of leaf assimilation area between 2000-2004, by study plots years leaf assimilation area (cm ) years Salix alba B13 Örtilos Salix alba B16 Vízvár Salix alba B15 Bélavár Alnus glutinosa B14 Gyékényes 2000 5.47 5.69 24.82 2001 5.93 5.44 5.09 21.9 2002 4.22 4.93 3.99 26.02 2003 5.22 5.35 5.23 26.49 2004 6.35 5.87 5.07 28.55 At study plot near Őrtilos (В 13) average surface area of Salix alba changed between 4.22 and 6.35 cm 2 during study interval (Fig.l). Assimilating leaf surface area was the smallest in 2002, the largest in 2004. At study plot near Vízvár (В 16) changes of average leaf area of Salix alba were a little smaller (Fig.2), but the smallest it was also in 2002 (4.93cm 2 ), the largest also in 2004 (5.87 cm 2 ). At study plot near Bélavár (В 15) research has began a year later. The smallest value was measured here too in 2002 (3.99 cm 2 ), but the largest value was measured in 2003 (5.23 cm 2 ). Leaves of Alnus glutinosa are significantly larger then those of Salix alba. Average leaf surface area during study interval has changed between 21.90 and 28.55 cm 2 (Fig.4); the smallest was in 2001, the largest in 2004. Result of the study show definite correlation between leaf size and water supply of the growing place. Changes of assimilation area of Salix alba, living in low floodplain, show the closest correlation with changes of water level of the river. Smallest values were measured at every plot in 2002, which inevitably shows a strong correlation with lower water levels of this period, resulted by less precipitation. Water supply of growing place of Alnus glutinosa depends partly also on water level changes of river Drava, but it is
