SD19: Phleum arenarium-Arenaria serpyllifolia dune annual community: Tortulo-Phleetum arenariae (Massart 1908) Br.-Bl. & de Leeuw 1936

Summary

Constant species

Ammophila arenaria, Arenaria serpyllifolia, Carex arenaria, Festuca rubra, Phleum arenarium.

Rare species

Mibora minima, Vulpia membranacea.

Physiognomy

The Tortulo-Phleetum comprises generally open assemblages of ephemerals which make a brief appearance in the dampness of spring and early summer among gaps in a cover of perennial grasses and dicotyledonous herbs of semi-fixed to fixed dunes.

The most distinctive species of the community are the annual grass Phleum arenarium with Arenaria serpyllifola, Cerastium diffusum ssp. diffusum, Aira praecox and Viola tricolor ssp. curtisii and the moss Tortula ruralis ssp. ruraliformis. Ammophila arenaria, Festuca rubra and Carex arenaria are consistently represented in the grassland matrix in which this vegetation makes its appearance, together with Ononis repens, Lotus corniculatus, Senecio jacobaea and, more occasionally, Poa pratensis.

Light-demanding mat plants like Thymus praecox and Sedum acre figure quite commonly and there are occasional records for Cerastium semidecandrum, Desmazeria marina, Euphorbia paralias, Logfia minima, Erophila verna, Trifolium dubium, T. campestre, Erodium cicutarium, Geranium molle and Centaurium erythraea. This community also provides a locus for the nationally rare Mibora minima and Vulpia membranacea.

In addition to T. ruralis ssp. ruraliformis, Hypnum cupressiforme is frequent, Homalothecicum lutescens, Brachythecium albicans and Tortella flavovirens occasional. Peltigera canina can also occur with some local abundance.

Habitat

The Tortulo-Phleetum is a community that capitalises on the appearance of gaps with essentially stable sand that develop where semi-fixed and fixed dune swards are opened up by drought or locally disturbed, often by rabbits or modest anthropogenic activity.