Auswirkungen des Extremhochwassers 1999 auf die Flächendynamik und Bestandsstruktur der Uferröhrichte des Bodensees Effects of the extreme flood in 1999 on the spatial dynamics and stand structure of the reed belts in Lake Constance Klaus Schmieder 1, * , Michael Dienst 1 , Wolfgang Ostendorp 2 1 Institut für Landschafts- und Pflanzenökologie (320), Universität Hohenheim, D-70593 Stuttgart, Germany 2 Limnologisches Institut, Universität Konstanz, D-78457 Konstanz, Germany Received February 8, 2002 . Accepted March 11, 2002 Abstract In consequence of the extreme flood at Lake Constance in 1999 the reed belts showed a se- vere loss in vitality so that a permanent damage could be expected. The monitoring project presented here focuses the documentation of the damage following the disturbance event, the identification of co-factors, and is designed to find out significant stressors that may impede the recovery of the reeds. The monitoring is based on CIR aerial photo interpretation, quanti- tative GIS-analyses and field data. The design of the study implies the definition of five de- grees of damage using the interpretation of CIR aerial photo series from July 2000. The aquatic reed beds were digitised and areal sums were calculated. These data were compared with the corresponding data from 1999 and 1993. Stand structural and biomass attributes were investigated in 50 randomly distributed permanent plots covering all site types and da- mage degrees. The results showed a loss of about 24 hectares of aquatic reeds at Lake Con- stance Untersee alone. The stands which had survived showed a great patchiness in terms of culm density, shoot population composition, culm architecture, and aboveground biomass production. Severely damaged stands were mainly composed of secondary shoots, whereas primary and insect infested shoots dominated in less damaged stands. One co-factor which explained the patchiness was the vertical position of the stand, i.e. the probability of being severely damaged increased with increasing distance below mean water level. The monito- ring programme will be continued till 2003. Key words: Phragmites australis – reed decline – disturbance ecology – flooding sensibility – stand structure – aerial photo interpretation – GIS – Lake Constance 0075-9511/02/32/02-131 $ 15.00/0 Limnologica (2002) 32, 131–146 * Corresponding author: Dr. Klaus Schmieder, Institut für Landschafts- und Pflanzenökologie (320), Universität Hohenheim, D-70593 Stuttgart, Germany; e-mail: schmied@uni-hohenheim.de Limnologica 32, 131–146 (2002) © Urban & Fischer Verlag http://www.urbanfischer.de/journals/limno