The distribution of Iberian gypsophilous flora as a criterion for conservation policy
Within the EU territory, gypsum habitats with a peculiar flora are exclusively restricted to the eastern half of the Iberian Peninsula. The Habitats Directive considers the scrublands belonging to the Gypsophiletalia order as priority habitats (habitats 1,520). Although these scrublands do not represent the only kind of vegetation associated with gypsum outcrops, they tend to occur together with other types of communities that grow exclusively on this substrate. As far as vascular flora is concerned, there are some species that grow exclusively on Iberian gypsums and are accordingly included in the Spanish Red List. Besides, given the fragmentary character and punctuated location of these outcrops, the protection of this Iberian habitat and its flora is, therefore, an enormous challenge for any preservation policy. The disjunct distribution of the flora faithfully reflects this geological feature of gypsum areas. Consequently, a proper and detailed knowledge of the distribution of the gypsophilous vascular flora can be very useful in formulating an efficient preservation policy for these habitats. Using the checklist of the Iberian gypsophilous flora, we collected a wide data base with records of distribution arranged into 10 × 10 km UTM grids. For each of the 1,241 grids where at least one gypsophyte was recorded we reckoned a series of parameters in order to determine the priority level of the flora for preservation purposes. These parameters were specific richness, gypsophily level, continuous and discontinuous rarity and endangered level. Our analyses reveal serious gaps in the Spanish network of protected sites with gypsophilous flora, the most important being located in the Hoya de Baza.