Elytrigia repens co-occurs with glycophytes rather than characteristic halophytes in low-growing salt meadows on the southern Baltic Sea coast

Abstract

Baltic salt meadows of the supralittoral are recognizable by a low vegetation structure of perennial plants, distinct zonation, and the presence of characteristic species of high ecological value. This semi-natural, grazing-dependent vegetation is declining in overall distribution and habitat quality. Abiotic and biotic habitat changes as well as the loss of characteristic species and a simultaneous increase of Elytrigia repens are particularly concerning. We hypothesize that, if E. repens increases due to abandonment or other causes, characteristic salt-meadow species will be affected adversely. To investigate the floristic changes and salt meadow species loss over a wide area, we used a dataset of salt meadow plots from along the southern Baltic Sea coast, partitioned by different cover ranges of E. repens. Between these groups, we compared the abundance and frequency of characteristic salt meadow species. We additionally tested (Mann-Whitney-U test) relevant structural factors, plot-based indicator values and strategy types. E. repens indicated low incidence of characteristic salt-meadow species. Soil moisture, salinity and light availability were lower where E. repens occurred; mean vegetation height was increased. Five species co-occurred with Elytrigia repens (Achillea millefolium, Holcus lanatus, Poa pratensis, Schedonorus arundinaceus, Trifolium repens), showing simultaneously a low relative abundance in the remaining dataset. We discuss our findings in terms of frequently observed vegetation changes in the light of salt meadow abandonment. In conclusion, we draw up an easy-to-use method for monitoring salt-meadow medium-term dynamics for applied nature conservation purposes.