Halophytic flora and vegetation in southern Moravia and northern Lower Austria: past and present

Halophytic habitats are distinctive components of the landscape in southern Moravia, Czech Republic, and the Pulkau valley in northern Lower Austria. We provide a historical overview of their flora and vegetation since the early 19th century and describe the current state assessed in the field at all remaining sites in 2020. We summarized the historical and current distribution of 17 species with the strongest affinity for saline habitats in the study area: Bupleurum tenuissimum, Cirsium brachycephalum, Crypsis aculeata, C. schoenoides, Galatella cana, Glaux maritima, Juncus gerardii, Plantago maritima, Salicornia perennans, Samolus valerandi, Scorzonera parviflora, Spergularia marina, S. media, Suaeda prostrata, Taraxacum bessarabicum, Triglochin maritima and Tripolium pannonicum. Of these, Galatella cana, Salicornia perennans, Suaeda prostrata and Triglochin maritima are regionally extinct. We also characterized the bryoflora typical of saline habitats. We classified historical and newly recorded releves and identified 14 halophytic associations belonging to the alliances Chenopodion rubri, Meliloto dentati-Bolboschoenion maritimi, Cypero-Spergularion salinae, Salicornion prostratae, Puccinellion limosae, Juncion gerardii and Festucion pseudovinae. The vegetation of the alliance Salicornion prostratae had disappeared in the study area by the 1970s. The alliance Festucion pseudovinae, with the association Centaureo pannonicae-Festucetum pseudovinae, was recognized as a new vegetation type for the Czech Republic. Using soil pH and electrical conductivity measurements, we evaluated the relationships of individual species and vegetation types to soil salinity. This synthetic study shows that the once well-developed halophytic flora and vegetation in the study area steadily declined from the early 19th century to the 1980s, initially mainly due to drainage and after the mid-20th century due to the combination of drainage and cessation of grazing. The introduction of conservation management in the 1990s and ecological restoration contributed to stabilizing plant diversity at the last saline sites. The future of halophytic flora and vegetation depends on the continuation of conservation management.