Is penetration of non-psammophytes an underestimated threat to sand dunes? - a case study from western Pontic coast

The aim of this study was to identify how far the different dune types from one of the largest dune complexes at the Bulgarian Black Sea Coast are affected by the penetration of non-psammophytes and if there is an upward trend in their number. We studied the Kamchia dune system during 2013-2015. Vegetation was sampled at 162 plots along 12 transects systematically situated to cover three different habitats: embryonic, white and grey dunes. All vascular plants as well as cover percentage of each species and total vegetation cover were registered within each plot. The overall species list of the different dune types was additionally completed for the whole study area. A total 207 plant species were registered. They were classified into five groups as follows: psammophytes - 38, weeds and ruderals - 36, plants typical of grasslands and shrublands - 95, plants typical of forests - 18 and alien (including invasive) species - 20. Number and cover of defined groups were calculated in respect to their distribution in different dune habitats. Results show that grey dunes contain the highest percentage of non-psammophytic plants, which decrease towards white and embryonic dunes. The studied coastal area is still less influenced by non-psammophytes. It represents an example of a Bulgarian Black Sea coastal dune complex that is relatively unaffected by urbanization. The high floristic and habitat diversity deserve further effective protection.