Ammophila arenaria

Ammophila arenaria is a European and North African native plant. It occurs in Australia, Canada, Chile, Falkland Islands (Malvinas) (sub-Antarctic), New Zealand, South Africa and United States (USA).[9]

Usually occurs on sand dunes, sometimes in inland sites with low fertility.[10] It occurs in the Wellington region and extends from to 55 to 32 degrees south latitude. In the Northern Hemisphere, it grows between 30 and 63 degrees north latitude.[11] Occurs in Chatham Islands, Otago Region, Doughboy Bay and Mason Bay.

Marram grass grows on coastal sand dunes all over the world. It prefers growing on the active sand area and the windward side of the foredune. It prefers well-drained soils with different kinds of mineral compositions and low in organic matter. The optimal soil conditions for marram grass is a soil pH from 4.5-9.0, soil temperatures from 10-40 degrees Celsius,[12] and salt concentrations of no more than 1.0-1.5%.[13] Marram grass can also be found on alkaline soils with a high pH of around 9.1 and also acidic soils with pH less than 4.5. Adult plants can tolerate a large range of chemical issues. Marram grass has an ability to adapt dry sand well. Its leaves become rolled and tight when moisture levels are low.[11]

A. arenaria is one of the most problematic noxious weeds of coastal California. This sand-adapted grass was introduced to the beaches of western North America during the mid-19th century to provide stabilization to shifting sand dunes. It grew readily and it can now be found from California to British Columbia. The grass is invasive in the local ecosystems, forming dense monotypic stands that crowd out native vegetation, reduce species diversity of native arthropods, and cover vital open stretches of sand used for nesting by the threatened western snowy plover (Charadrius nivosus).[2] The plant's spread has changed the topography of some California beach ecosystems, especially in sand dunes. The presence of this grass was a major cause of the destruction of native dune habitat in Oregon and Washington during the 20th century,[14] where it was planted precisely for its dune-stabilizing effect.[15]

Several methods have been employed in attempts to eradicate the grass in California, including manual pulling, burning, mechanical removal followed by salt water irrigation, and glyphosate application.[14] Studies to find the best methods are ongoing.

Not only is it invasive in California, it is also a highly invasive weed in coastal areas of New Zealand and Western Australia, where it was introduced for the same purpose in California, to stabilise dunes; outcompeting native spinifex species.