Morphometric structural analysis of Phragmites australis stands in Lake Balaton

Hungarian Academy of Sciences, Balaton Limnological Research Institute, Klebelsberg Kuno út 3, Tihany H-8237, Hungary

^* Corresponding author: donvito@tres.blki.hu

Received: 10 June 2011
Accepted: 17 February 2012

Abstract

Phragmites australis is a stand forming emergent macrophyte that displays large phenotypic variation within Lake Balaton. The present study assesses morphological variations of P. australis within three transects of different reed stands of Lake Balaton which differ with respect to bathymetry, reed quality and geographic position in order to achieve a morphological typization. On average the southern stable stand produced the largest and thickest plants (295±9 cm and 7.5±0.2 mm), while plants of the northern die-back stand were approximately half this size (141±2 cm and 3.5±0.1 mm). The slow growth and development of Phragmites characterizing the northern die-back stand was the result of fewer and shorter internodes, which also resulted in the low number of green leaves. The most influential factor shaping the phenotypic properties of the plants was determined to be the reed quality (general condition), although site-specific differences, shore-specific differences, water depth and spatial position within reed stand transects were also found to be significant. Despite the differences in the studied stands and almost certain genetic dissimilarities, three morphological ecotypes of Phragmites were distinguished on the basis of stem height to basal diameter ratio, stem density and phenotypic plasticity of plants. These ecotypes were primarily correlated to water depth at their position within the reed stand. The similarity of the spatial distribution of stem heights to basal diameter ratios and phenotypic plasticity of plants along all studied reed stands suggests that morphological typization should be considered to provide additional information on ecological zonation of stands.