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   British habitats   
 
   Waxcap Grassland   


Distribution: North-western Europe, but becoming fragmentary and rare. British examples appear to be more extensive than those surviving on the European continent. Certain old lawns, both in north-western Europe and elsewhere, may be included in this habitat concept.


INTRODUCTION

'Waxcap grasslands' are not a single grassland type. The concept cuts across the communities recognised by the National Vegetation Classification (NVC) and a current problem is that by doing so, such grasslands do not necessarily match site selection criteria as adopted by the statutory, national nature-conservation bodies. They are, basically, sites with a high species richness in certain key fungal groups, notably Hygrocybe species (waxcaps), and they characterise locations which are agriculturally 'unimproved' and have relatively high grazing levels (by cows, sheep, horses, rabbits or other equivalent herbivores). Grasslands need to be semi-natural (certainly not reseeded) but, very importantly, they must also have no recent history of fertilisation. The 'better' sites, i.e. those with a higher species richness in the key fungal groups and with key indicator species present, are those where there has been no application of fertilisers at least in the past 30 years (D.Boertmann, pers. comm., 1998). A small number of the fungi of such sites figure in the British fungal red data list (Ing, 1992), but substantially more figure in a number of the European red data lists (Arnolds & de Vries, 1993; Ing, 1993).

In areas of intensive agriculture, survival of such sites is limited. In general, they are confined to rocky ground and steep slopes, often on summits of hills. Elsewhere, their survival is just a matter of chance, perhaps where a particular farm has adopted other agricultural priorities.
In Britain, there are large tracts of hill turf used primarily for sheep-grazing, and these may include areas of 'waxcap grassland'. The better sites are often on thin soil, sometimes associated with past disturbance, e.g. along ancient trackways and by old mines and quarries. However, except on limestone and ultrabasic rocks such as basalt and serpentinite, these hill grasslands may be too nutrient-poor to support many of the rarer and more 'special' species.

 
A site in the hills near Girvan, south Ayrshire (S.W. Scotland).
Here the area is predominantly wet, nutrient poor moorland that locally has been drained to allow limited hill-farming. However, an outcrop of serpentinite forms a higher ridge of better-drained and more nutrient-rich land. The thinness of the soil and its isolation from the richer agricultural lands of south Ayrshire mean that it is left as part of the sheep grazings. It is a mycologically important site, not only as a 'waxcap grassland' but also for a number of unusual or rare fungi associated with rockrose (Helianthemum nummularium).

 
Here, again in south Ayrshire, the serpentinite forms a steep-sided hill. The left side of the hill is composed of a more nutrient-poor rock and the fungal assemblage is limited. The foreground and the righthand slopes are on the serpentinite and the site is rich in all of the key assessment groups (probably the best such site in S.W.Scotland). Rare species such as Hygrocybe spadicea, Entoloma incanum and Microglossum atropurpureum (= Thuemenidium atropurpureum) have occurred here. The site is another with fungi associated with rockrose.


A special case of grazed grassland is the lawn. While the grazing 'herbivore' is actually a lawnmower and the site is more likely to be level and free from rocks, the habitat otherwise may be much the same. Established lawns usually have been fertilised at some point in the recent past and are more likely to produce fungi of such genera as Mycena and Conocybe, or, if waxcaps are present, they may only be tolerant species such as Hygrocybe conica. However, some ancient lawns may be rich in waxcap species and be of considerable conservation value. Rotheroe (1995) described one such lawn in Wales.


 

THE FUNGI

 
Basic to the concept of 'waxcap grasslands' are, of course, waxcaps, i.e. species of the agaric (toadstool) genus Hygrocybe. Such grasslands may be studded with brightly coloured fruitbodies in late autumn. H. punicea, shown here on the south Ayrshire hill illustrated above, is a species particularly characteristic of the higher-grade sites.


Mycologists and mycocoenologists have recognised for many years the existence of Hygrocybe-rich grasslands. However, working in Denmark, Rald (1985) reported significant loss of such grasslands and suggested that the number of species present in one site can be used as an assessment of its conservation importance, from minor or local to national importance (in accordance with Danish environmental registration practice). Seventeen or more species was the criterion for national importance, though it was acknowledged that these would not all be found in a single visit. According to Boertmann (1996), twenty Danish sites meet this criterion.


Number of species of Hygrocybe
as a criterion for conservation importance of Danish 'waxcap grasslands'
(from Rald, 1985)
Local valueRegional valueNational value
4 - 89 - 1617 - 32


Meanwhile, in Sweden, J.Nitare was working on the ascomycete family Geoglossaceae (earthtongues) and he found there had been an 85% loss of documented Geoglossaceae sites over two decades (Nitare, 1988). Consequently, Nitare extended Rald's approach to include other fungal groups characteristic of these same unimproved grasslands:

  • the agaric genera Entoloma and Dermoloma as well as Hygrocybe, and including the closely allied Camarophyllopsis with the latter.
  • the 'fairy clubs' (Clavariaceae) (especially Clavaria and Clavulinopsis)
  • the earthtongues (Geoglossaceae) (Trichoglossum, Geoglossum, Thuemenidium and Microglossum).


Numbers of species as criteria for conservation importance of Swedish 'waxcap grasslands'
(adapted from Nitare, 1988)
Fungal genus or familyLocal valueRegional valueNational value
Hygrocybe + Camarophyllopsis5 - 89 - 1314 - 25+
Entoloma (esp. subgenus Leptonia)4 - 67 - 910 - 20+
Dermoloma222 - 3+
Clavariaceae   (fairy-clubs)3 - 56 - 89 - 13+
Geoglossaceae   (earthtongues)2 - 34 - 56 - 10+


It will be noted that Nitare's criteria differ a little from Rald's.

Useful English language reviews of this Scandinavian work have been provided by Arnolds (1991, 1992) and Boertmann (1996). The last of these gives details of some interesting updates. A pioneering study at a site in Ireland was described by Feehan & McHugh (1992). What, then, is the situation in Britain?


 

WAXCAP GRASSLANDS IN BRITAIN

As noted above, areas of unimproved grassland are more extensive in Britain. Nevertheless, sites with a high species-richness in Hygrocybe and other key assessment taxa are certainly not common. Undoubtedly, use of fertilisers has caused considerable impoverishment, and while pastures with a few tolerant species such as the white Hygrocybe virginea are widespread, high grade sites are rare. Even so, it may well be that the Rald-Nitare criteria are insufficiently rigorous for application in Britain. British site data are needed.

The author of this page was, for some years, attempting to gather such data, with particular reference to the need for comparative data for work in south Ayrshire. The problems are that fruiting periods are often very short and abruptly terminated by dry periods or the first heavy frosts, that only in certain years do some sites seem to reveal anywhere near their full diversity, and that productive periods tend to clash with academic workloads. A long drive to a supposed key site in order to record just two Hygrocybe species is all too commonplace. What was needed was a national sampling strategy with input from a number of mycologists.

Such a survey has been in operation by the British Mycological Society (Rotheroe et al., 1996) and data on Scottish sites and certain specified species (Hygrocybe spadicea, H. calyptriformis, Microglossum olivaceum) were also gathered in relation to the British Biodiversity Action Plan (Newton et al., 2000; Newton , 2003). There is a growing body of data that confirms the importance of British sites in a European context.

Microglossum olivaceum, an earth tongue, a Biodiversity Action Plan species that occurs in thin, base-rich turf in scattered localities throughout Britain. The colour varies from olive green to blue-green, mahogany brown to almost black, often with mixtures of these colours (blackish fruit bodies usually have blue-green stalks, distinguishing them from other blackish earth tongue species). (Rare variants, perhaps separate species, are cinnamon brown or carmine pink.) Photographed near Abergavenny, South Wales, 1998. Any reports of this species are very welcome, specimens should be dried and colour notes kept.

Since its inception in 1996, the UWS 'Biological Conservation' module has included field visits to a site that includes fragments of waxcap grassland of evident regional significance, i.e. Muirshiel in the Renfrewshire hills. For supplementary information for this exercise, click here.


References
•   Arnolds, E. (1991). Mycologists and nature conservation. In: Hawksworth, D.L. (ed.), Frontiers in mycology, CAB International, Wallingford, pp. 243-264.
•   Arnolds, E. (1992). Macrofungal communities outside forests. In: Winterhoff, W. (ed.), Fungi in vegetation science. Handbook of vegetation science, 19/1, Kluwer, Dordrecht, pp. 113-149.
•   Arnolds, E., & de Vries, B. (1993). Conservation of fungi in Europe. In: Pegler, D.N., Boddy, L., Ing, B., & Kirk, P.M. (eds.) Fungi of Europe: investigation, recording and conservation, Royal Botanic Gardens, Kew, pp. 211-230.
•   Boertmann, D. (1996). The genus Hygrocybe, Fungi of Northern Europe, 1 (2nd printing), Danish Mycological Society.
•   Feehan, J., & McHugh, R. (1992). The Curragh of Kildare as a Hygrocybe grassland. Irish Naturalists Journal 24: 13-17.
•   Ing, B. (1992). A provisional red data list of British fungi. The Mycologist 6: 124-128.
•   Ing, B. (1993). Towards a red list of endangered European macrofungi. In: Pegler, D.N., Boddy, L., Ing, B., & Kirk, P.M. (eds.) Fungi of Europe: investigation, recording and conservation, Royal Botanic Gardens, Kew, pp. 231-237.
•   Newton, A., Holden, E., Davy, L., Holden, E., Silverside, A., Watling, R., & Ward. S.D. (2003). Status, distribution and definition of mycologically important grasslands in Scotland. Biological Conservation 111: 11-23.
•   Newton, A., Holden, E., Davy, L., Silverside, A., & Watling, R. (2000). Survey of 'waxcap' Hygrocybe grasslands and compilation of species dossiers on three grassland fungi. Report to Scottish Natural Heritage, pp. 36.
•   Nitare, J. (1988). Jordtonger, en svampgrupp på tillbakagång i naturlige fodermarker. [Earth-tongues, a declining group of macrofungi in seminatural grasslands.] Svensk Bot. Tidskr. 82: 341-368.
•   Rald, E. (1985). Vokshatte som indikatorarter for mykologisk værdifulde overdrevslokaliteter. Svampe 11: 1-9. [With English summary]
•   Rotheroe, M. (1995). Saving an historic lawn: conservation progress report. The Mycologist 9: 106-109.
•   Rotheroe, M., Newton, A., Evans, S., & Feehan, J. (1996). Waxcap-grassland survey. The Mycologist 10: 23-25.


Note: Like much of this site, this page is under development and continuing review. Interested readers (if any) should check back from time to time. An update is planned.



© A.J. Silverside
e-mail: alan.silverside@uws.ac.uk
Page first hosted at www-biol.paisley.ac.uk/bioref/, November 1998 and revised at various times; transferred to lastdragon.org with minor edits, October 2009 (update pending)
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