Comparative growth responses and population ecology of European and American beachgrasses (Ammophila spp.) in relation to sand accretion and salinity

Marram (European beachgrass; Ammophila arenaria (L.) Link) and American beachgrass (A. breviligulata Fern.) are coastal dune-colonizing grasses which were formerly treated as a single species. They were distinguished taxonomically on the basis of traits with no obvious ecological importance. Ammophila species have been regarded as ecologically equivalent, and the species distinction itself has been questioned. In this thesis, critical aspects of growth and colonizing ability in relation to sand accretion and salinity were compared in these putative "ecological equivalents".;Both Ammophila species possess moderate salinity resistance in terms of survivorship and growth response to substrate salinity, and may be classified as salt-resistant glycophytes. In these respects, A. breviligulata is more salt-resistant than A. arenaria. In both species, however, 104 hr immersion in cold seawater failed to reduce viability of dormant vegetative propagules, and repeated short-term inundation of plants by seawater did not kill established seedlings. Clonal integration allowed A. breviligulata ramets to grow vigorously at high salinity levels which were either lethal or highly inhibitory to isolated ramets.;The results from the experiments on these populations and from the literature imply that there are important ecological differences between Ammophila spp. in traits relating to colonization, growth, and clonal spread in beach and dune environments.;Populations from Wales U.K. and Maine U.S.A. were grown in artificial dune plots constructed near London, Ontario. Sand accretion up to 50 cm yr...