Ewa Szczęśniak1, Zygmunt Dajdok1, Marek Krukowski and Magda Podlaska2
1Department of Botany, University of Wrocław, pl. Uniwersytecki 1, 50-137, Wrocław, Poland
2Department of Botany and Plant Ecology, Wrocław University of Environmental and Life Sciences, Wrocław, Poland
In Poland, the flora of halophytes is rather poor and originally associated with dunes or wet salt meadows along the coast of the Baltic Sea and with over a dozen inland sources of salt water. In Lower Silesia, halophytes are originally absent because there is a lack of natural open salt deposits, saline soils or sources of salt water. Up to the end of 20th century, only sporadic and ephemeral stands of a few halophilic plant species were recorded (e.g. Glaux maritima and Puccinelia distans).
As an effect of intensive salt deicing during the last 20 years, a group of plant species benefiting from this process appeared. The soil salinity is the highest in the beginning of vegetation season and strongly limits germination of native non-halophilic plant species. We documented 82 patches of vegetation associated with salty soils and distinguished two groups of halophytes.
The first group consists of obligatory or facultative halophytes native to Central Europe, preferring saline substratum or tolerating it (e.g. Plantago coronopus, Spergularia salina, Puccinelia distans, and Polygonum aviculare agg). These species start to grow in early spring and are limited to narrow patches (max. 50-80 cm wide) of shallow puddles along roads, with periodically standing salt water and long lasting salt content. Their community refers to association Puccinellietum limosae Soó 1933 of the class Festuco-Puccinellietea Soó ex Vicherek 1973, native to natural salt meadows in Poland.
The second group consists of alien drought resistant thermophilic plants, germinating 4-8 weeks later than the native species. High salinity eliminates previously germinating plants which enables these species to start growing without competitors. During germination, the salinity level is already low, and therefore these species are calledpseudo-halophilic species. They occupy dry and warm well drained roadsides and the middle lanes of highways. Over the past decades, we observed their rapid expansion; earlier they were eliminated by frosts. Almost all patches are dominated by one alien species, for example, Dittrichia graveolens, Senecio inaequidens or Atriplex micrantha.
In total, 137 species of vascular plants were noted in all samples, however the composition of the patches seems to be highly accidental and about 80% of the species occurs in less than 10% of patches. Almost all seedlings of sporadically noted plants observed in late summer and autumn did not survive the winter deicing season. Alien species comprised 30% of sporadically noted plants, 52% of constantly present, and 83% of dominating or co-dominating species. Halophytes or pseudo-halophytes were 3%, 47% and 66%, respectively.