Inventory of the halophytes in inland central Europe

There is a long tradition in Europe of assigning ecological indicator values to plants and using these values in ecological research. A special case is that of the salt-tolerant species. Saline soils are extremely heterogeneous and their physical and chemical properties vary significantly with microrelief and between alternating dry/wet seasons. The complexity of such soils suggests using salt indicator values. This study resulted in the first multi-country database of vascular plants occurring in inland salt marshes and on salt steppes in temperate Europe based on expert revision of the literature and field experience. The inventory of the 190 salt-tolerant species was carried out according to their quantitative representation in saline and non-saline habitats. These species were each classified into one of three categories of salt tolerance (obligate halophytes, facultative halophytes, accessory/associated species) assigned salt numbers on a nine-point scale reflecting their individual preference for soil salinity based on their calculated halophytic value. Saline soils are reliably indicated by the presence of obligate halophytes; these specialists grow exclusively in natural saline habitats. Only 45 species are assigned to this group, while 61 species make up the group of facultative halophytes and 84 are accessory species with a wide ecological niche, occurring more or less accidentally in saline habitats. Their number is likely to increase since every plant (non-halophyte) recorded in a saline habitat can be considered to be an accessory species. The obtained salt numbers showed a close consistency with the recently used salinity indicator values estimated by Ellenberg, Borhidi and Breckle; in terms of categories of salt tolerance, only slight differences were detected.