Modelling Habitat Distribution of Mediterranean Coastal Wetlands: The Ebro Delta as Case Study

Abstract

Present-day altered distribution of the natural habitats in the Ebro Delta is consequence of intensive human settlement in the last two centuries. We developed spatial predictive models of potential natural wetland habitats of the Ebro Delta based on ecogeographical predictors and presence/pseudo-absence data for each habitat. The independent variables (i.e. elevation, distance from the coast, distance from the river and distance from the inner border) were analysed using Generalized Additive Models (GAMs). Elevation and the distance from the coast appeared as key predictors in most of the coastal habitats (coastal lagoons, sandy environments, Salicornia-type marshes and reed beds), whereas distances from the river and from the inner border were relevant in the most terrestrial or inland habitats (salt meadows, Cladium-type marshes and riparian vegetation). Our findings suggest that the most inland habitats (i.e. Cladium-type marshes, salt meadows and riparian vegetation) would have undergone a severe reduction (higher than 90 %), whereas in the most coastal habitats (coastal lagoons, sandy environments, Salicornia-type marshes) the reduction in relation to their potential distribution would be around 70 %. This modelling approach can be applied to other deltaic areas, since all them share a similar topography.