THEORETICAL HABITAT TEMPLETS, SPECIES TRAITS, AND SPECIES RICHNESS - AQUATIC MACROPHYTES IN THE UPPER RHONE RIVER AND ITS FLOODPLAIN

1. The objective of this study, which is based on forty-two species of hydrophytes and helophytes, is to investigate: (i) relationships amon g species traits; (ii) habitat utilization by species; (iii) the relat ionship between species traits and habitat utilization; (iv) trends in species traits in the framework of spatial-temporal habitat variabili ty, and if trends match predictions from the river habitat templet; an d (v) trends in species richness in the framework of spatial - tempora l habitat variability, and if trends match predictions of the patch dy namics concept. 2. Two data sets were used for this analysis: species traits (mainly reproductive and morphological characteristics) were do cumented from the literature; and species distribution across eight ha bitat types was from field surveys conducted in the floodplain of the Upper Rhone River, France. This information was structured by a fuzzy coding technique and analysed by ordination methods. 3. Several specie s traits, which are related to disturbances and reflect resistance (e. g. attachment to soil or substrate) or resilience (e.g. potential for regeneration of an individual), are closely related for aquatic macrop hytes. 4. Habitat utilization by aquatic macrophytes separates the hab itat types along a gradient of connectivity with the main channel, whi ch corresponds to a gradient in flood disturbance frequency and the pe rmanence of the different water-bodies. 5. The relationship between sp ecies traits and habitat utilization is highly significant, indicating that a particular set of habitat types is used by taxa with a particu lar set of species trait modalities. 6. Observations in one habitat te mplet (in which scaling of the templet is primarily based on water lev el fluctuation's for the temporal variability axis and on substrate ch aracteristics for the spatial variability axis) generally do not suppo rt predictions on trends in species traits but do support predictions on trends in species richness. 7. Observations in an alternative habit at templet (in which scaling of the templet is based on frequency of f lood scouring for the temporal variability axis and on heterogeneity o f the substrate for the spatial variability axis) support theoretical predictions on trends for about half of the species traits for which p redictions were available. However, trends in species richness in this alternative habitat templet are only partly in agreement with predict ions.