Waxcap grassland is a type of short-sward, nutrient-poor grassland that supports a diverse range of larger fungi, particularly waxcaps (species of Hygrocybe and related genera), which are characteristic of such habitats. Waxcap grasslands are principally found in Europe, where they are declining due to agricultural practices. Consequently, the fungal species are of conservation concern, and efforts have been made in the United Kingdom and elsewhere to protect both the grasslands and their characteristic fungi. Thirty European species of waxcap grassland fungi are currently assessed as globally "vulnerable" or "endangered" on the IUCN Red List of threatened species.[1]
The association of waxcaps with unimproved (nutrient-poor) grasslands was first noted in 1949 in the Netherlands,[2] but current interest was stimulated by a series of papers published by Dutch mycologist Eef Arnolds in the 1980s.[3][4] Arnolds not only confirmed the association of waxcaps with unimproved grasslands, but also noted the rapid decline of such habitats in the Netherlands.[4] Similar studies were subsequently undertaken elsewhere in Europe, initially in Denmark[5] and the United Kingdom.[6]
Definition and description
Waxcap grasslands are characterised by being unimproved (unfertilised and nutrient-poor), with a short sward due to grazing or mowing. They are also moss-rich and long-established, not having been recently sown.[7][8] They occur in both upland and lowland areas and may be found on acidic, neutral, or calcareous soil. They support a wide range of characteristic larger fungi, but may not be equally species-rich in plants.[7]
In 1995, Rald proposed a simple method of counting the number of waxcap species present at a given site in order to assess its value as a waxcap grassland. He suggested that sites with 17 or more species were of national importance, those with 9–16 species were of regional importance, those with 4–8 species of local importance, and those with 3 or fewer of no importance.[5] This system was modified by Rotheroe and others to include all the characteristic macrofungi, not just waxcaps.[6]
Known as the "CHEG" system, this is widely used in survey work today. The acronym "CHEG" stands for the main groups of relevant fungi: C - the clavarioid species (club and coral fungi); H - species of Hygrocybe and related genera (waxcaps); E - Entoloma species (pinkgills); and G - the geoglossoid fungi (earthtongues). More recently the modified term "CHEGD" has been used to include species of Dermoloma, Pseudotricholoma, Camarophyllopsis, and Hodophilus which also inhabit these grasslands.[9]
Conservation
Over the past 75 years, more than 90% of unimproved grasslands in Western Europe have been lost, primarily due to agricultural intensification[10] through ploughing, reseeding, manuring, and the application of fertilizers and other chemicals.[4][7] The maintenance of a short sward through grazing or mowing and the subsequent removal of cuttings has also been shown to be important for waxcap fruiting. It has been found that hay cutting in July, followed by aftermath grazing or mowing to 3cm is optimal.[8] In 1988, Arnolds estimated that only around 200 hectares of unimproved waxcap grasslands remained in the Netherlands.[3]
As a result, both the unimproved, nutrient-poor grasslands and the larger fungi that are characteristic of such grasslands are of conservation concern. Currently, 30 waxcap-grassland species are classified as globally "vulnerable" or "endangered" on the IUCN Red List of Threatened Species.[1]
In the United Kingdom, survey work has shown that surviving waxcap grasslands are more extensive than in many other European countries, thanks mainly to large areas of unimproved upland sheep pastures and also to many unimproved lawns (especially in churchyards and country houses) and amenity grasslands.[10] Nonetheless, five species characteristic of waxcap grasslands - Entoloma bloxamii, Porpolomopsis calyptriformis, Hygrocybe spadicea, Microglossum atropurpureum, and Microglossum olivaceum - were formerly the subject of national Biodiversity Action Plans[11] and waxcap grasslands as a specific habitat were the subject of several local Biodiversity Action Plans.[12][13] Four species - E. bloxamii, H. spadicea, M. atropurpureum, and M. olivaceum - are currently listed as "Priority Species" under Section 41 of the Natural Environment and Rural Communities Act (in England)[14] and Section 7 of the Environment (Wales) Act (in Wales).[15]
Waxcap grassland surveys have been undertaken by the British Mycological Society,[6] the National Trust,[21]Plantlife,[22] and the various national conservation bodies.[23][24] A leaflet on managing waxcap grasslands in Britain and Ireland has been published by Plantlife and the Fungus Conservation Forum.[25]
Translocation
Translocation has been proposed to mitigate the loss of waxcap grasslands. [26] However currently there is no evidence of successful translocation.[27]
↑Schweers ACS. (1949). "Hygrophorusweide, een associatie". Fungus. 19: 17–18.
12Arnolds E. (1988). "The changing macromycete flora in the Netherlands". Transactions of the British Mycological Society. 90 (3): 391–406. doi:10.1016/s0007-1536(88)80148-7.
123Arnolds E. (1989). "The influence of increased fertilization on the macrofungi of a sheep meadow". Opera Botanica. 100: 7–21.
12Rald E. (1995). "Vokshatte som indikatorarter for mykologisk verifulde overdrevslokaliteter". Svampe. 11: 57–65.
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