Dune plant assemblages are affected by severe conditions, which makes them excellent models for studying the effects of species interactions and environmental conditions on community structure. We evaluate the relationship between the structure of dune communities, local environmental conditions and the suitability of climatic conditions for their characteristic species. Using data from an extensive survey of xerophytic inland sand dune scrub communities from Portugal – one of the most threatened habitat types of Europe – we identify the main gradients of vegetation composition, the different types of communities and their indicator shrub species. Then, we model the geographical responses of these species to the environment. Soil organic matter, isothermality and the habitat suitability for Stauracanthus genistoides defined the distribution of three shrub communities in the study area.