CHANGES IN THE VEGETATION OF DISUSED WET MEADOWS IN SUBGLACIAL CHANNELS OF THE KASHUBIAN LAKELAND (NORTHERN POLAND)

摘要

In a representative area of the Kashubian Lakeland (Northern Poland), changes in vegetation resulting from the cessation of use of wet meadows were determined. The study area, at the bottom of a subglacial channel, comprises a complex of terrestrialized, spring and percolating mires. The original material consisted of maps of actual vegetation prepared on the basis of aerial photographs from 1991 and 2004 and phytosociological and floristic studies in 1984, 1994 and 2004. The chronology of cessationof use of the wet meadows was determined from archival aerial photographs from 1964—1981 and the authors' mapping of vegetation in 1991-2004. It was found that the vegetation underwent significant quantitative and qualitative changes: generally, the gradual disappearance of fen communities (mainly Menyantho-Sphagnetum and Caricetum rostratae) caused by invasion of Phragmites australis, Carex acutiformis and Alnus glutinosa. The expansion of Phragmites australis and Phalaris arundinacea also resulted inthe disappearance of sedge communities, chiefly Caricetum acutiformis, C. caespitosae and C. paniculatae, which were formed shortly after mowing stopped.