“No sin mi sueloareniscas del aljibe y endemismo botánico en la `Herriza´ o brezal mediterráneo

Resumen

Mediterranean heathlands or Herrizas are one of the most characteristic plant communities within the Strait of Gibraltar. These heathlands are found in mountain summits and ridges on rocky, scarce soils derived from Oligo-Miocene sandstones, known as “Aljibe sandstones”. Besides their low pH and fertility, these soils are characterized by a high soluble aluminum content, a toxic element for plants. These sandstone soils can be considered as truly edaphic islands since they are embedded in a matrix of limestone or marl derived soils characterized by higher pH and fertility. The high diversity and abundance of plant endemics make this habitat outstanding within this geographic region. These endemic species are tightly associated to sandstones soils, as they are edaphic specialists. The main aim of this study is to illustrate the sandstone-plant endemism association within the Strait of Gibraltar region. For this purpose, the presence and abundance of woody plant species in the herrizas were sampled. In addition, the surface covered by sandstone soils in a 10 Km radius circle around every sampled plot (buffer area) was measured. Our results showed a positive correlation between the abundance of soil specialists, most of them endemics, and the proportion of sandstones within the 10 Km buffer. These results highlight the higher vulnerability of the soil specialists in patchy, isolated sandstone areas, more frequent in the African side of the Strait of Gibraltar.