Northern Ireland's Priority Species

Abietinella abietina – fir tamarisk-moss

 
Abietinella abietina
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Abietinella abietina (Hedw.) Br.Eur.
Family: Thuidiaceae

A. abietina is a distinctive small pleurocarpous moss with erect stems and spreading branches, reminiscent of a tiny conifer. Its rare variety abietina grows with the commoner var. hystricosa on coastal sand dunes.

In brief

  • In Northern Ireland var. abietina is known only in Co. Londonderry. The records are from the Magilligan area (1926-2008) to Castlerock (1926-1938); it was refound at Ballymaclary in 1999 and 2008
  • It is only recorded in Northern Ireland on calcareous sand in coastal dunes. At Ballymaclary Nature Reserve it grows in short vegetation of moss-carpets on dry edges of a dune-slack, often near to Rhytidium rugosum, Hylocomium splendens and sparse Salix repens
  • The species is perennial and can be found in all months of the year
  • Var. abietina is a Northern Ireland priority species because it is on the Irish Red List, classed as Endangered and the site in Co. Londonderry is the only remaining Irish locality
  • Main threat(s) / causes of decline include loss of habitat through golf-course development and degradation of habitat where scrub and tall grassland become established

Species description
A. abietina has arcuate to erect stems 2-8 cm high (rarely 12 cm) from which branches arise in four ranks. Its rather sparse branches often spread at wide angles. The stem leaves are patent, broadly ovate, plicate at the base and taper to a long acuminate apex. Branch leaves are more concave, broadly ovate to lanceolate, with a shorter apex.

Life cycle
The plants are dioicous and capsules are unknown in Ireland and rare in Britain. No gemmae, tubers or other propagules have been recorded, so dispersal probably occurs from stem and leaf fragments.

Similar species
A. abietina differs from the closely related Thuidium species in having only a simply pinnate rather than two- or three-pinnate (and complanate) arrangement of branches, but shares their strong costa extending to above mid-leaf and almost isodiametric, unipapillose upper leaf cells. The main distinctions between var. abietina and var. hystricosa are that the former has shorter, ovate branch leaves which are appressed when dry, whereas the latter has longer, ovate to lanceolate branch leaves some of which are secund when dry, so that dry branches of var. abietina are terete and neatly cylindrical whereas those of var. hystricosa appear rough due to projecting leaf apices.

How to see this species
Var. abietina can be found in short vegetation of dune-slacks at Ballymaclary Nature Reserve, where it grows with var. hystricosa.

Current status
Restricted to Co. Londonderry, where recorded from the Magilligan area (1926-2008) to Castlerock (1926-1938). It was refound at Ballymaclary in 1999 and 2008, with strong populations in one dune-slack.

Why is this species a priority in Northern Ireland?
Var. abietina fulfils the following Priority Species Criteria:

  • Decline (1% year), the Irish population now restricted (R) to Northern Ireland following extinction in Co. Dublin
  • Irish Red Data Book (RDB) species classed as endangered (EN)
  • Red-listed species in Ireland

Threats/Causes of decline
The apparent extinction of populations in Co. Dublin was due to coastal development in the Malahide and Portmarnock areas, where houses, other buildings and golf-courses have replaced the former dune-grassland and slacks. In Co. Londonderry habitat has probably also been lost to the extensive golf-course development at Castlerock, while protected dune areas at The Umbra and elsewhere now have much tall under-grazed vegetation that is unsuitable for the species. Where var. abietina persists at Ballymaclary the short, open vegetation at edges of dune-slacks is maintained by intense rabbit grazing. A. abietina would be vulnerable to any reduction in this grazing pressure. Other potential threats could include damage to the thin vegetation cover by military vehicles that use the area, or changes in hydrology.

Conservation of this species

Current action

  • The site for this species at Ballymaclary N.R. is designated as an ASSI by NIEA
  • Recent records of the species at Ballymaclary N.R. were made during surveys by NIEA, which did not relocate the species elsewhere on the coast of Co. Londonderry

Proposed objectives/actions

  • Maintain the number of viable populations of the species
  • Maintain the range of the species
  • Maintain appropriate habitat management on its sites at Ballymaclary N.R.

What you can do
Careful study by a skilled bryologist is needed to confirm identification of this species. New sites should be reported to NIEA and the British Bryological Society's Recorder for Mosses (see below).

Further information

Links
British Bryological Society

Literature
Atherton, I., Bosanquet, S. & Lawley, M. (eds) (2010). Mosses and liverworts of Britain and Ireland: a

field guide. Wootton, Northampton: British Bryological Society.
Lockhart, N., Hodgetts, N. & Holyoak, D. (2012). Rare and threatened bryophytes of Ireland. NMNI, Belfast.
Smith, A.J.E. (2006). The moss flora of Britain and Ireland. 2nd ed with corrections (paperback). Cambridge: Cambridge University Press.

Text written by:
David Holyoak