The effect of microhabitats on vegetation and its relationships with seedlings and soil seed bank in a Mediterranean coastal sand dune community

We examined species composition and diversity of vegetation and soil seed bank associated with different microhabitats in Mediterranean semiarid sand dune conimunity, to identify which functional groups or species benefit from trampling, and to provide a basis for management. In this community microhabitats were found to significantly influence species abundance and biomass of dominant functional groups and dominant species. The open patches generally have the greatest species richness, diversity and productivity. The highest value of similarity occurred during June to September and the lowest value occurred in April when seedling emergence stopped but before new seeds dispersed. Shrubs did not benefit their understorey plant functional groups except for perennial forbs and Apiaceae due to their denser canopy and larger litter amount. Trampling decreased the species diversity of vegetation and did not facilitate the establishment of herbaceous plants, but was beneficial for some functional groups such as Apiaceae and Brassicaceae as well as some species such as Polycorpon succulentum. A positive relationship was found between productivity and diversity in this community and on the trail, but the relationship in the open area and shrub understorey was not significant. This work can provide a deeper understanding of small-scale vegetation processes and mosaic patterns of distribution. (c) 2008 Elsevier Ltd. All rights reserved.