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The aim of this study was to analyse and quantify the effects of the canopy of the nativeinvasive N-fixer woody shrub Retama monosperma in the dune ecosystem, affecting the structure and function of the dune environment as well as plant community, in the context of the facilitation mechanism. Air temperature and relative humidity; soil pH, electric conductivity, organic matter (OM) and nutrient content; above and below-ground vegetation biomass, litter mass, species richness and Shannon diversity were determined and compared from sampling plots below the R. monosperma canopy and in canopy gaps within a coastal dune system in SW Spain. The relationships between soil OM and nutrient contents and above and below-ground vegetation biomass, litter mass, species richness and Shannon diversity were also assessed. A predominance of positive interactions was confirmed. The canopy of R. monosperma ameliorated temperature extremes beneath, and soil OM and nutrient concentrations were increased by 188-466%, compared to those found in gaps. Plant biomass increased by 442% beneath the canopy and was composed almost exclusively of herbaceous annuals. Plant diversity was not affected. Plant communities were clearly structured as fertility islands, distributed in an environmentally stressful dune matrix characterized by scarce vegetation cover and low biomass.

The aim of this study was to establish whether rabbit endozoochory affects plant community structure and whether it contributes to the dispersal of new species to areas open to colonisation. Fresh pellets were collected throughout the study area and from the youngest sandbars. The series of bars represents a gradient in terms of their age and Retama monosperma cover. At least 14 different species germinated from rabbit pellets and seed dispersal were observed throughout the year. Our results indicate that endozoochory is very important in dune ecosystems as it allows for the dispersal and colonisation of plants species with no evident dispersal mechanisms and those with several dispersal mechanisms.