The influence of hydromorphological variables on benthic invertebrate (BI) assemblages was studied in Slovenian rivers and ecoregions Alps, Dinaric western Balkan and Pannonian Lowland. Data on BI assemblages were obtained from 302 sampling sites between the years 2005 and 2011. For each sampling site data on 49 environmental variables were collected and were assigned to four environmental variable groups: regional natural characteristics (typology), land use, river habitat quality variables (RHQ), and river habitat modification variables (RHM). The relation of environmental variables on BI assemblages was analyzed using canonical correspondence analysis (CCA). In general, RHQ variables explained higher share of BI assemblages% variability than RHM variables. The importance of environmental variables was dependent on ecoregion. The explained variability of BI assemblages was devided among groups of environmental variables using partial CCA. The effects of tipological variables and RHQ or RHM variables were well discerned. Tipological variables constrain the processes on smaller scales, but a considerable part of BI assemblage composition is dependent on habitat quality features irrespective of typological characteristics. pCCA between land use variables and other environmental variable groups showed the highest joint effects of explained variability of BI assemblages with tipological variables. We have well discerned among land use effects and RHQ or RHM variables on BI assemblages. Using ecologically relevant morphological variables the guiding images of river habitats of four major European regions were defined. Significant differences were observed among river habitats of alpine, lowland, mediterranean and karst region, and guidance for river management was presented. The relationship between BI assemblages and different combinations of previously used morphological variables was also analysed and generally more variability of BI assemblages was explained than with individual morphological variables.
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