Determinants of floating island vegetation and succession in a recently flooded shallow lake, Kis-Balaton (Hungary)

摘要

Floristic composition and vegetation succession were studied in relation to abiotic factors on secondarily developed young floating islands. These had formed after the reflooding of a drained wetland where mature floating fens had been present. We selected two floating fen Kis-Balaton Hungary complexes with similar physiognomy as references and performed stratified sampling with strata distinguished according to species dominance in all three sites. Species cover was estimated in 5 m x 5 m quadrats and the resulting data set was analysed with correspondence analysis. Interstitial (ground)water and soil parameters were measured and vegetation composition were recorded subsequently on the site in Kis-Balaton. Results were evaluated with canonical correspondence analysis including forward selection to test for significant abiotic variables: plots formed three main groups in the ordination space. One group contained ruderal vegetation, while the other ones were characterised by sedges and willows respectively. According to the forward selection, available nitrogen content of the soil was responsible for the segregation of the ruderal group from willow scrubs.