Are there habitats that contribute best to plant species diversity in coastal dunes?

Abstract

The following paper describes patterns of diversity across major habitat types in a relatively well\ud preserved coastal dune system in central Italy. The research addresses the following questions: (a) whether different\ud habitats defined on the base of a land cover map support similar levels of biodiversity in terms of vascular flora\ud richness and number of rare and endangered species, and (b) how each habitat contributes to the total species\ud diversity of the coastal environment. A random stratified sampling approach based on a detailed land cover map was\ud applied to construct rarefaction curves for each habitat type and to estimate total species richness. In addition, the\ud number of exclusive, rare and endangered species was calculated for each habitat type. Results highlight the\ud importance of the coastal dune zonation (embryo-dune, main dune, transition and stabilized dune) in species\ud conservation because they harbour progressively higher species richness. However, differences among these habitats\ud were not significant, so no particular species rich "hotspots" could be evidenced. On the contrary, rarefaction curves\ud show that the upper beach (strand) habitat sustains significantly smaller number of species, but surprisingly, it shows\ud the highest rarity values and highest proportion of endangered species. Therefore, for the establishment of successful\ud biodiversity conservation programs in these coastal environments, it is imperative not only to conserve biologically\ud rich hotspots but also to include species poor habitats containing endangered or unique elements. Thus, the complete\ud coastal vegetation mosaic including all coastal habitats is important to adequately characterize the plant species\ud diversity of coastal dune ecosystems

Darwin's naturalization hypothesis: scale matters in coastal plant communities

“…91 grid cells fall within the limits of the studied regions, however only 71 contained holocenic dunes. For the finer resolutions we used presence-absence data from a long-term (2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)) random sampling campaign of coastal dune vegetation in several study sites, comprising most of the best conserved remnant dune systems of the region (about 80 km on the western coast and 22 km on the eastern coast) (for more details see Acosta et al 2009, Carboni et al 2011. In this work we specifically consider two nested plot dimensions: 2 × 2 m (4 m 2 ) as the finest resolution and an expansion of the plots to 8 × 8 m (64 m 2 ) as the intermediate resolution of analysis.…”

Aeolian dynamics of beach scraped ridge and dyke structures

“…This process the may be capable of aiding the dune building process (Lynch et al, 2009). The double structures topographic heterogeneity is also advantageous for the development of a more diverse flora and fauna if vegetation is allowed or encouraged to grow or is planted (Acosta et al, 2009). …”

Impact of human activities on coastal vegetation ? A review

“…Coastal dune ecosystems experience well marked littoral-inland gradients as regards environmental factors such as substrate coherence (which influences probability of burial by sand) and salinity, wind, salt spray and wave regime, which differ with distance from the sea and topographic sheltering (Ranwell, 1972;Guara-Requena, 1989;Acosta et al, 2009;Lortie andCushman, 2007 in Macedo, 2008;Carranza et al, 2008;Acosta et al, 2013). These gradients act as a strong selective force, which determines the occurrence of species developing different strategies (Martí nez et al, 2004b;Fenu et al, 2012).…”

“…Very few and highly specialized vascular plant species can survive here, with specific morphological and physiological traits (Garcí aMora et al, 1999;Acosta et al, 2009). These pioneer species must possess a high salt tolerance and features that allow the survival to sand instability and burial.…”

“…However, despite the low number of plant species, these habitats are characterized by high rarity and conservation values, because of the high proportion of endangered and exclusive plant taxa (Van der Maarel, 2003;Acosta et al, 2009, Martins et al, 2013. In a comprehensive study of invertebrates in UK and Wales, Howe et al (2010) found that the most specialized dune invertebrates tend to occur in the earlier stages of dune succession, the number of specialists declining as the proportion of bare sand decreases.…”