Austria’s largest saline soil region is located in the south of Seewinkel with a total area of 25 km². The saline soils can mainly be found at the shore of the lake and at the regions in the centre of Seewinkel, where there is no gravel. There, where the soil is not covered with gravel and sand layers, so-called “Solontschak-soil” (Russian: sol=salt; Kirghiz:tschaki=flowering) develops.
In this sandy, light, unstratified soil, salt migrates upwards with the rising water during dry periods, where it remains after evaporation of the water as a salt efflorescence. Until the early 20th century, this salt from the surface was taken and used for producing soap.
In the case of the second soil type of the area, the “Solonetz”, the salt-containing stratum is found some 35 to 70 cm beneath the surface. It is covered with an argillaceous low-salt layer upon which humus can form. During dry periods, the soil shrinks due to its high organic compound, cracks open and forms small tetragonal columns. The main soil of the Seewinkel is made of both types of soil; the “Solontschak-Solonetz”.
Plants can only absorb the water bound by the salt if they manage to maintain an osmotic potential higher than that of the soil, in order to ensure the uptake of water.
Specialised plants, that can tolerate high levels of salt in their cells, are called halophytes. Some of these plants are halophytic: they actually need the high concentration of salt to survive, but most of them could live just as well or even better on non-saline soils.
Plants have developed different ways of handling the salt:
- some plants increase the water-storage capacity in the leaves, like the succulent halophytes.Lepidium cartilagineum and the Sea Purslane(Atriplex portulacoides)
- some plants form vesicular (salt) hair that simply falls off (different kinds of Atriplex)
- some plants like Sea Arrowgrass (Triglochin maritinum), Sea Plantain (Plantago maritima) grow leaves that fill with salt and then fall off.
Saline soils are a sign that there formerly existed a sea, but the soils of the Seewinkel are very different from saline soils of coastal areas like the German north-western seashore. The main salt of the sea is the sodium chloride. The Seewinkel salt has been transformed by sediment accumulation and shifting: alkaline soda prevails whereas common salt, Glauber salt and Epsom salt are rare.
Inland saline soils are characterised by a high concentration of soda during dry periods. The soda concentration in seashore soils increases with humidity. This is the reason for different fauna and flora in inland and seashore saline soils.
There are salt plants that can be found around the world like the Media Sandspurry (Spergularia maritima) and the Sea Purslane and Eurasian species like the Strawberry Clover (Trifolium fragiferum) living in inland regions as well as at the seashore. But Pannonian saline soils are dominated by continental species. The Pannonian region is rich in species, like the Small-headed Thistle (Cirsium brachycephalum), found in relatively small areas. Many species that can live on seashore saline soils and inland saline soils formed subspecies, like Tripolium pannonicumisthe Pannonic subspecies of the Sea-aster. During its flowering time in autumn the grasslands surrounding the saline lakes of the Seewinkel are covered with violet blossoms.
Poor grassland soil is as humid as normal soil during springtime and autumn but almost desiccates during summer. That’s why it is called mesoxerophytic grassland. Here plants can thrive that developed special adaptations to survive the dry periods. Some have very strong roots, like the Field Eryngo (Eryngium campestre). Some grow very small leaves to reduce evaporation, like the Hard Fescue (Festuca pseudovina) or the needle-shaped leaves of the Lady’s Bedstraw (Galium verum). TheArtemisia santonicum (a wormwood-species growing on saline soils) is very hairy and the Field Eryngo has developed a cyan wax coating for protection.
In the inundation area there are the “Puccinellia-meadows” of the “Solontschak”. Its character species is the salt-tolerant Puccinellia peisonis.