The term “waxcap grassland” is used to describe grasslands supporting rich fungal assemblages comprising genera that are characteristic of nutrient-poor habitats. Waxcap (Hygrocybe spp.) species themselves are usually well represented and are probably the most visible group present but other fungal groups such as the fairy clubs (Clavariaceae), earthtongues (Geoglossaceae) and the genus Entoloma are also indicative of this habitat.
Low nutrient status is the essential requirement for these grassland fungi, which are highly sensitive to soil enrichment from nitrate-based fertilizers. The underground fungi mycelia are thought to be slow-growing and species-rich sites must, therefore, have developed over long (several decade) timescales uninterrupted by detrimental actions such as ploughing or fertilisation. As a result, waxcap grasslands are usually indicative of unimproved and often ancient grassland sites.
Sites can be found across a range of grassland types with a history of low disturbance (from fertilizer or ploughing) and a short sward maintained by either grazing or mowing. Neutral grasslands of the MG5 NVC type and close-grazed acidic grasslands (often U4) often support waxcap populations and these sites are often also of high botanical interest. However, many of the best waxcap grasslands are either close-cropped by grazing livestock or frequently mown and this type of management may not always be desirable as a conservation tool. Therefore the nature conservation value of such sites is likely to have been overlooked or viewed as low.
Notable waxcap grasslands can occur in rigg and furrow pasture, providing that it is essentially unimproved. There appears to be a strong correlation here between the presence of adder's tongue fern ( Ophioglossum vulgatum ) and high counts of waxcap species. Field woodrush (Luzula campestris) and the moss Rhytidiadelphus squarrosus are frequent associates in waxcap grasslands. Good sites can also be found in churchyards, garden lawns, parkland and on golf courses. Some of the top UK sites are found on the old lawns associated with large country houses, e.g. Roecliffe Manor in Leicestershire where the presence of 27 waxcap species resulted in its designation as a Site of Special Scientific Interest, the first such site to be notified in the UK. The Llanishen and Lisvane Reservoir Embankments in Cardiff (constructed in ca. 1880) were notified as an SSSI in 2006 based on the 28 waxcap species present.
The much-quoted statistic of a 97% loss of Britain 's herb-rich grasslands since the 1930's must have similarly devastated many waxcap populations. The current situation is unclear but it appears that lowland sites are now highly fragmented and many populations small in size.
Sites can occur anywhere in the region but the greatest concentrations are found in the Durham uplands where the impacts of modern agriculture have been less intensive. Good sites can also be found across the Coal Measures area in Gateshead Borough and Derwentside. However, the true distribution of waxcap grasslands in County Durham is still largely unknown.
Current or recent activity
A number of waxcap grasslands have been identified recently (2005-2006) during surveys undertaken by Andy McLay, and as part of the Coalfields and Lowlands and MAGical Meadows projects run by the Durham Widllife Trust.
“Improvement” of amenity waxcap grasslands such as parkland, churchyards and golf courses by nitrate-based fertilizer applications or moss-reducing herbicides. A well-developed moss layer appears to be an essential requirement and this is often viewed unfavourably by park groundsmen and gardeners.
Damaging agricultural practices such as ploughing and reseeding and fertilizer application still threaten some grasslands. Spray drifting from adjacent land is also a potential problem.
The cessation or reduction of livestock grazing poses a threat to many sites, particularly in the lowlands where good sites are often small, isolated and no longer economically viable as grazing units.
Excessive grazing during the fruiting season can result in trampling of fruit bodies. Similarly, high levels of public access, use of motorbikes, off-road vehicles or heavy machinery can also cause physical damage.
A lack of awareness and understanding of the ecological requirements of grassland fungi. Fungi conservation is still a relatively new concept and more work is needed to ensure that fungi and their habitats receive an adequate degree of recognition and protection within the planning system.
Inappropriate tree planting schemes on old semi-natural grasslands.
Atmospheric pollution. High levels of nitrogen deposition over long periods could potentially lead to eutrophication and loss of waxcap diversity.
More information / references
Boertmann D. (1995). The Genus Hygrocybe - Fungi of Northern Europe - Volume 1. Danish Mycological Society, Denmark.
Evans S. (2003). Waxcap Grasslands – an assessment of English Sites. Report No.555 . English Nature.
Griffith G.W., Bratton J.H., Easton G.(2004). Charismatic Megafungi – The Conservation of Waxcap Grasslands. British Wildlife
Thompson R. (2000). The Somerset Grassland Fungi Report-1997-1999. Somerset Environmental Records Centre
Waxcap Website – www.aber.ac.uk/waxcap