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

1. For Trichoptera occurring in two sites of the Upper Rhone River (Fr ance) we examine: (i) relationships among species traits; (ii) habitat utilization of Trichoptera species; (iii) the relationship between sp ecies traits and habitat utilization; (iv) trends of species traits in the framework of spatial-temporal habitat variability to test predict ions of the habitat templet concept; and (v) trends of species richnes s in the framework of spatial - temporal habitat variability to test p redictions of the patch dynamics concept. 2. Of the sixteen species tr aits selected, twelve have high correlation ratios for the seventy-fiv e species used in this analysis; these traits are related to behaviour al, morphological, or physiological aspects. Traits related to reprodu ction or life cycle have lower correlation ratios. 3. An ordination by species traits separates the five main families into three groups: (i ) Hydropsychidae and Polycentropodidae; (ii) Hydroptilidae; and (iii) Leptoceridae and Limnephilidae. An ordination of the habitat utilizati on of the species in ten habitats indicates that the Hydropsychidae oc cur preferentially in the main channel, Hydroptilidae, Polycentropodid ae, and Limnephilidae occur in backwaters or oxbow lakes, and the Lept oceridae are ubiquitous. 4. The Hydropsychidae exhibit a relationship between species traits and habitat utilization, i.e. they use similar habitat types with similar species traits. The species traits of the o ther four families are similar but their habitat utilization is quite different. 5. The Hydropsychidae occur in lowest spatial-temporal vari ability habitats and Limnephilidae in the highest. Therefore, net spin ners and filterers are characteristic of habitats with a low spatial-t emporal variability, whereas shredders and case makers using plant mat erial are characteristic of habitats with high spatial-temporal variab ility. The trends in species traits show little agreement with trends predicted from the river habitat templet. 6. Trends of species richnes s in the framework of spatial and temporal variability do not follow t he predictions of the patch dynamics concept because richness is simil ar in all superficial habitats. This implies that each habitat, in spi te of large differences in their spatial and temporal variability, off ers Trichoptera a similar but limited number of ecological niches.