Huperzia selago (L.) Bernh. ex Schrank & Mart., Fir Clubmoss
Account Summary
Native, occasional. Circumpolar boreo-arctic montane.
1881-2; Barrington, R.M.; eastern range of Cliffs of Magho.
Throughout the year.
Fermanagh occurrence
In Fermanagh, this small, evergreen perennial is widespread but not abundant, mainly on strongly acidic, nutrient-poor, peaty, high ground on the Western Plateau plus in a few outlying sites in the Carnmore area. Local habitats include mountain summits and slopes, ledges, screes, open moorland and bogs. It has been recorded in a total of 44 tetrads (8.3% of those in the VC), but it has not been refound in six previous sites recorded in the 1940s and early 1970s. The lost sites are: Gadalough, N of Keenaghan Lough; Lough Scolban; Mullaghmore (the famous Erica vagans (Cornish Heath) site); Lough Doo near Little Dog; Brennan's Rocks, N of Lough Mulderg; and Pollnagollum. While these areas need to be searched to confirm the local extinction of this species, the evidence suggests that Fir Clubmoss has suffered habitat loss mirroring that observed in other parts of its British and Irish range.
The only area where H. selago occurs nowadays in any considerable quantity in Fermanagh is on the exposed summit ridge of Cuilcagh, the highest mountain where the rocks peek through the shallow, acid, nutrient-poor blanket peat. Throughout the year, on the blasted heath, H. selago pokes up its short, stiff, yellowish-green, bushy tufts between the stones on bare peaty ground or where surrounded by a carpet of grey-green Racomitrium moss and wind-pruned, flat-growing dwarf woody shrubs, for example, Erica cinerea (Bell Heather), Calluna vulgaris (Common Heather or Ling), Vaccinium myrtillus (Bilberry), V. vitis-idaea (Cowberry) and Empetrum nigrum (Crowberry).
Ecology
As the Fermanagh tetrad map shows, elsewhere in the VC, Fir Clubmoss is fairly frequent in open areas on scarps and peat bogs on the Western Plateau, and less so in open ground on lowland blanket bogs and heaths whenever competition is reduced. In the latter situation, H. selago usually occurs as individual plants occupying well-drained sites, often on acid, peaty soil close to large rocks, where competition from heather subshrubs and other species is reduced, probably by the shallowness of the substrate. Similar competitive conditions occur when Fir Clubmoss grows on upland cliff and rock ledges. It has also been suggested that the lowland sites of H. selago may lie in damp frost pockets, the cold soils of which would again restrict the growth of competitors (Jermy et al. 1978; Jermy & Camus 1991).
On the other hand, Page (1997) emphasises that all H. selago sites, whether on sandy or peaty soils, seem to be particularly free-draining ones, and that the species is tolerant of very exposed conditions, being able to survive both considerable winter cold and summer sun. However, the species does appear to be susceptible to heavy grazing pressure and populations are even more vulnerable to heathland fires, whether accidental or used to manage heathers, as the plants are readily eliminated by burning (Page 1997).
British occurrence
In Britain, H. selago has become very rare or extinct in many of its former lowland heathland sites, indeed in most of these it has not been seen for nigh on a hundred years (Page 1988). While the reasons for this major decline of the species in Britain are not fully understood, undoubtedly changes in the pattern of land use involving habitat loss, changed methods of vegetation management – perhaps involving heavier agricultural stocking levels, or using herbicides and fire to manage vegetation – plus increased levels of air and soil pollution have all been suggested as possibly significant contributory factors (Page 1988). While air pollution can be absolutely discounted in our area, the most obvious and notable examples of this sort of change in the Fermanagh context are the development of extensive hectares of forestry plantation on the Western Plateau and, until recently, the drainage, cutting, ploughing and fertilizer spraying of our lowland bogs.
Irish occurrence
Despite a possible or real decline, H. selago is almost certainly still the most widespread of the five clubmoss species that occur in Ireland, having been found at least once in all 40 vice counties (Scannell & Synnott 1987). The 1996 edition of Webb's An Irish Flora describes Fir Clubmoss as, "frequent but local, mostly above 300 m, but sometimes on lowland bogs" (Webb et al. 1996).
World distribution
The species is widespread in the northern circumpolar region and numerous varieties also extend worldwide and penetrate far into the southern hemisphere, eg to the Falkland Islands, Tierra del Fuego and Tasmania (Hultén 1962). Elsewhere in W Europe, H. selago has a widespread occurrence throughout western and northern parts of Britain and Ireland, Iceland, Scandinavia and western central European countries south to the Alps and the Pyrenees (Jalas & Suominen 1972).
Fossil record
Fossil spore evidence proves the presence of H. selago in Britain and Ireland, especially in northern parts, from the late phase of the last glaciation onwards (ie from the Late Weichselian onwards, throughout the entire Flandrian period) (Godwin 1975).
Current trends
Historical records show that Fir Clubmoss formerly occurred widespread throughout Britain and Ireland except in some counties in S, E and C England. Nowadays, while it is still common in Scotland, H. selago has lost much of its former ground in England and Wales. A count of the pre- and post-1930 symbols for England and Wales on the BSBI Atlas map indicates that of a total of 140 hectads plotted, 73 had pre-1930 records only for H. selago (Perring & Walters 1976; Godwin 1975). The 1978 Fern Atlas published a revised hectad map which incorporated considerably more records for England and Wales and of the 227 symbols, 127 were for post-1930 records of H. selago, although the overall pattern of losses from the S and E of England was obvious (Jermy et al. 1978). Changes recorded during the BSBI Monitoring Scheme in 1987-88 appeared to indicate a decline in England but an increase in Wales. The authors of the relevant report (Rich & Woodruff 1990), however, reckoned these changes were not significant.
In comparison, The New Atlas of the British and Irish Flora which reports survey data up until the end of 1999, maps H. selago from a total of 1223 hectads. A visual count of Irish hectads in the New Atlas found a total of 213 squares displayed, 61 of which had pre-1970 records only. The data behind the New Atlas map suggests that most Fir Clubmoss losses took place early on (pre-1930), due to habitat changes associated with agricultural intensification. While this process has continued, the overall distribution of H. selago appears stable in these islands (A.D. Headley, in: Preston et al. 2002).
Reproduction
H. selago plants often reproduce prolifically by vegetative means producing sizeable 'bulbils' or 'gemmae' which are budded off from near the tops of stems. In form these are small, leafy, 'trident-like' flattened buds formed in rings around the erect stems, about one cm below the large terminal bud (Page 1997). These abundant propagules are efficiently dispersed by wind in the autumn and they root and rapidly establish new daughter plantlets which grow between one and two cms tall in their first year (Page 1988).
However, Fir Clubmoss plants also produce vast quantities of pale yellow asexual spores, which again are efficiently wind-dispersed. As far as RSF can discover, nothing is known about the efficiency of Huperzia spore germination in the field, nor about recruitment of plants from this biological source (Page 1988, 1997). I think this matter could be accurately described as a field of near total scientific ignorance, which applies not only to clubmosses, but for most pteridophytes and bryophytes.
Even on the question of the longevity of individual plants and their population turnover, little or nothing is definite and everything is qualified; for example, "H. selago appears to be a relatively short-lived plant, which slowly builds up its tufts over several seasons and then probably reaches an abrupt and fairly rapid demise." (Page 1997). Clearly, if in the future Fir Clubmoss is to be actively conserved, whether under a Biodiversity Action Plan designation or not, closer study will be urgently required to clarify the reproductive capacity and population dynamics as well as identifying the significant environmental pressures affecting the species in typical habitats.
Names
The current author has not been able to discover as yet the derivation of the genus name 'Huperzia', which first came to my notice with the first volume of Flora Europaea (first edition), in 1964. The specific epithet 'selago' is a reuse of a previous generic name: it was first used by the Classical Roman Pliny to refer to a plant resembling Sabina herba, a synonym of Juniperus sabina (Gilbert-Carter 1964).
Threats
Afforestation of upland areas, overgrazing, the use of fire to manage hillside vegetation and the possibilities of consequent soil erosion are the main threats.