Ellenberg ecological indicator values, tolerance values, species niche models for soil nutrient availability, salinity, and pH in coastal dune vegetation along a landward gradient (Euxine, Turkey)

Coastal dunes are characterised by plant species adapted to harsh conditions. Salinity and other factors (soil pH, nutrients, and climate events) vary along the landward gradient. The current study investigated the effects of environmental factors on the occurrence and composition of coastal dune plants. Ellenberg ecological indicator values (EIVs), species tolerance values (TVs), and species niche models for salinity, nutrient availability, and soil reaction were determined. EIVs were estimated using weighted averages based on the species cover-abundance for each plot. Species TVs were calculated considering the cover-abundance and EIVs (pH, nutrient, and salinity). Species niche models were determined with the general linear model (GLM). GLM was computed using mean community EIVs, canopy height, and climatic variables. We found that salinity (S) and pH (R) EIVs decreased along the seaside-inland gradient while nitrogen (N) EIVs increased. TVs for S increased landward while S and R TVs decreased. According to GLM, niche models of 28 species for salinity, 25 species for pH, and 21 species for nutrient were significant. In summary, salinity and pH are the main drivers shaping coastal dune zonation and plant community.