Growth of three meadow species along a salinity gradient in an inland saline habitat: transplant experiment

Abstract

The mechanisms of vegetation zonation were determined in order to provide an advice for restoration of natural saline habitats. Field experiments were conducted to examine the response of mature plants to different edaphic conditions. Three dominant species Salicornia europaea L., Puccinellia distans (L.) Parl. and Elymus repens (L.) Golud, characteristic of distinct zones along the salinity gradient (ECe 28.5–2.3 mS/cm) were studied. Results from a 2-year reciprocal transplant experiment demonstrated that species were restricted to every zone mostly by a salinity level. The obligatory halophyte S. europaea had optimal growth conditions at its home site. This is an opposite result to the one known from inland salt marshes of North America. A distinct growth limitation of transplants was observed in the P. distans and E. repens zones of lower salinity. Fewer individuals and lower aboveground biomass were recorded in the P. distans zone, whereas in the E. repens zone all seedlings died in the second year of observations. The glycophyte E. repens from the less saline site (ca 2.3 mS/cm) was strongly inhibited in the most saline S. europaea zone (15.8–28.5 mS/cm). Compared to the control transplants in the S. europaea zone it had shorter new shoots, fewer and shorter shoots, lower above-ground biomass and biomass of rhizomes. The P. distans transplants were markedly limited in the E. repens zone of lower salinity. Fewer and shorter new shoots, flowering shoots, lower above-ground biomass and biomassof grasses’ roots were noted in the transplants of this zone. Since P. distans was found in non-saline areas outside the investigated meadow this effect could not result from the salinity level but from E. repens interaction. The obtained results suggest that for restoration of natural saline habitats the most important is to keep or rebuild the original salinity level of soils. As the second point the control of strong competitors by cutting or grazing should be considered.