Comparative Study of the Response of Four Native to the Bulgarian Black Sea Coast Psammophytes to Simulated Flooding Experiments

Aims: This study aimed 1) to determine and compare the effects of flooding stress, caused by storms on whole plants of four native to the Bulgarian Black Sea Coast psammophytes and how long their rhizomes can remain viable in sea water; and 2) to investigate post-immersion changes in plant biomass and allocation to above- and below-ground biomass in order to determine and compare their capacity as dune stabilizers.

Methodology: Two simulated flooding experiments were conducted. In the first experiment, whole plants were immersed in sea water for 20 days. Visible morphological changes of leaves, stems and roots are recorded and assessed in 12 parameters. In the second experiment, rhizomes were immersed in sea water, were planted and allow growing for one month before harvesting in order to establish rhizomes viability, biomass and root/shoot ratio.

Results: Conducted flooding experiments established that investigated psammophytes were very tolerant to immersion impact and salt stress. Whole plants stay viable longer than the flood with a maximum duration along the Bulgarian Black Sea Coast, and rhizomes were able to regenerate after 30 days in seawater. Statistical analysis of experimental data demonstrates that immersion in sea water increases rhizomes viability, biomass and allocation to root biomass, whereas other factors, such as duration of immersion and temperatures of sea water have not significant effect.

Conclusion: Investigated psammophytes show high tolerance to sea water immersion and high viability during the simulated flooding experiments. Investigated species from family Cyperaceae are less tolerant to water immersion than those from Poaceae. According to growth response, Leymus racemosus subsp. sabulosus demonstrates a high potential to be a key species for dune stabilization, followed by Ammophila arenaria, Carex colchica and Galilea mucronata. All psammophytes could contribute to the protection of coastal sands during storms.