Physical disturbance by large herbivores can affect species diversity at the community level and concurrently
genetic diversity at the species level. As seedling establishment is rarely observed in clonal
plants, short-term experiments and demographic studies are unlikely to reveal the response of clonal
plants to disturbances. A long-term (30-year) field experiment and the availability of molecularmarkers
allowed us to investigate the clonal structure of populations of Elytrigia atherica subjected to different
management regimes. The long-term field study provided us with five replicated blocks that had
been subjected to three different management regimes, grazing by cattle, mowing and abandonment.
In this study we examined the effects of herbivore grazing andmowing on clonal richness and genetic
diversity of populations in salt marshes using multilocus microsatellite genotypes. In addition,
phenotypic traits and spatial positions of E. atherica ramets were determined for 20 samples in a 5 × 10m
plot in each of the blocks. Abundance and phenotypic traits were affected by the management
regimes, resulting in a higher abundance in abandoned fields and plants having shorter and narrower
leaves in managed fields. Biomass removal did affect the clonal structure of populations and increased
the genetic diversity compared to that in abandoned fields. However, no distinct difference was found
between the two management regimes, mowing and grazing. Although seedling recruitment has
rarely been observed, the present study shows that such rare events have occurred within the populations
studied. Thus, molecular tools can greatly increase our understanding of vegetation dynamics
and processes within populations growing under different conditions