UPLAND FLUSHES, FENS AND SWAMPS (UK BAP PRIORITY HABITAT)

Summary

This priority habitat takes in a number of wetland communities in the uplands, from swamp vegetation at the margins of lochs or in the waters of sluggish streams, through tall fens with mixtures of herbs and rushes, to sedge-dominated mires and bryophyte springs. Each has a characteristic set of species. In the tall fens and swamps the dominant are large sedges, rushes and, on neutral soils, herbs. On more acid soils and herbs are more common. The sedge mires can consist of any of many species either alone or in combination. Small herbs are common in these mires, depending on the base-status of the water. Bryophyte springs vary from the almost pure mats of a few specific mosses to intricate, brightly-coloured mixtures of species, dotted with small herbs.

All these types of vegetation rely on a wet but not stagnant habitat where water flows laterally over or through the ground. Since all are more common where the climate is cool and wet, they are most widespread in the uplands.

All of these communities are common throughout the uplands, though the montane flushes and springs are confined to the upper slopes of the higher hills. Swamps, fens and sedge mires can be found a few metres above sea level as well as on montane plateaux and hill tops.

These communities add a great deal to the structural and floristic diversity of upland vegetation, and are also home to a great many rare species. Wetland communities of all types are host to large numbers of invertebrates, especially flies and spiders, and so are valuable feeding grounds for many insectivorous birds, including waders.

Most of these Upland flushes, fens and swamps are open to grazing and probably need light grazing to maintain the structure and species diversity except at the very highest altitudes.

What is it?

The Upland flushes, fens and swamps priority habitat includes a very wide range of communities, from tall swards of herbs, rushes and sedges to mats and patches of bryophytes. What they all have in common is an association with water either in flooded ditches, channels or valley floors, or emerging from and flowing gently over the surface of the ground. For the purpose of description this varied priority habitat is split into 5 subdivisions related to NVC communities:

Swamps

Terrestrial swamp NVC communities – as opposed to those where the plants grow in deep water – are included in this priority habitat although they are also represented by the aquatic priority types where they form a very narrow waterside strip, or emergent stands in open water. They consist of species-poor, in some stands single-species, swards of bottle sedge Carex rostrata, bladder sedge C. vesicaria, great horsetail Equisetum fluviatile and common spike-rush Eleocharis palustris. In the more diverse examples there is an array of tall herbs such as bogbean Menyanthes trifoliata, marsh cinquefoil Potentilla palustris, bog pondweed Potamogeton polygonifolius, water mint Mentha aquatica, marsh marigold Caltha palustris and lesser spearwort Ranunculus flammula.

Tall fen communities

These are assemblages of plants such as soft rush effusus and sharp-flowered rush J. acutiflorus, purple moor-grass caerulea, flag iris Iris pseudacorus and herbs including meadowsweet Filipendula ulmaria, wild angelica Angelica sylvestris, meadow buttercup Ranunculus acris, R. flammula, Mentha aquatica, water avens Geum rivale, marsh bedstraw Galium palustre, ragged robin Lychnis flos-cuculi and common valerian Valeriana officinalis. The vegetation generally grows tall and lush. There is a sparse underlayer of bryophytes such as Calliergonella cuspidata, Rhizomnium punctatum and Brachythecium rutabulum.

Sedge mires or flushes

Shorter in stature than the tall fens, these are assemblages of sedges and other small species. Any of a number of sedges may dominate, including common sedge Carex nigra, star sedge C. echinata, carnation sedge C. panicea, common yellow sedge C. viridula ssp. oedocarpa, dioecious sedge C. dioica, C. rostrata, white sedge C. curta and russet sedge C. saxatilis. They vary from species-poor assemblages on acid substrates, with an underlayer of Sphagnum fallax, S. palustre and Polytrichum commune and a sparse interleaving of Ranunculus flammula, tormentil Potentilla erecta and marsh violet Viola palustris, to species- rich swards on base-rich soils with a flora including butterwort Pinguicula vulgaris, yellow saxifrage aizoides, purple saxifrage S. oppositifolia and alpine meadow-rue Thalictrum alpinum and a characteristic suite of bryophytes consisting of Campylium stellatum, Scorpidium scorpioides, Drepanocladus revolvens and Blindia acuta. Mesotrophic Carex rostrata mires may include tall herb species such as Mentha aquatica, Lychnis flos- cuculi, Filipendula ulmaria, Menyanthes trifoliata and Potentilla palustris. Potamogeton polygonifolius soakways, with or without marsh St. John’s wort Hypericum elodes, and Ranunculus omiophyllus-Montia fontana rill communities also belong here.

Springs

Springs mark out the sites where water actually emerges from the ground. They almost all consist of mats and patches of brightly-coloured bryophytes dotted with small vascular plants. Characteristic bryophytes of this habitat include the mosses Philonotis fontana, Bryum pseudotriquetrum, Dicranella palustris and Sphagnum denticulatum, and the liverwort Scapania undulata. Where the irrigating water is base-rich the most common species is the Palustriella commutata. Associated vascular plants include blinks Montia fontana, opposite-leaved golden saxifrage Chrysosplenium oppositifolium, starry saxifrage Saxifraga stellaris and Viola palustris. At high altitudes where snow lies late in spring, Anthelia julacea forms patches of its tiny, silvery shoots, and Pohlia wahlenbergii var. glacialis grows in spreads of apple-green leaves which have a waxy bloom.

Valley mire

The M21 Narthecium-Sphagnum valley mire is also partly within this priority type where it occurs in the unenclosed uplands. Its flora, with cross-leaved heath Erica tetralix, ling vulgaris, bog myrtle Myrica gale, white beak-sedge Rhynchospora alba and peat- forming Sphagnum mosses, is very different from that of the other flush, fen and swamp communities, but it shares the habitat of laterally moving water in a saturated soil.

How do I recognise it?

This priority type encompasses a wide range of plant communities, united by their need for a constantly wet habitat. They vary from valley mires and rushy pastures to herb-rich swards, sedge mires and montane springs and flushes. Sedges, rushes and bryophytes are the predominant species. This priority type includes some of our most species-rich vegetation and is home to some of our rarest species. These communities are also a valuable habitat for upland invertebrates and birds. For the most part they are maintained by light grazing.

Differentiation from other Priority Habitats

The flushes that occur only in the uplands: M7, M8, M11, M12 and M31-M38 belong by definition to this priority habitat. Those with a wider altitudinal range belong to this priority habitat where they occur in the unenclosed uplands (but not on limestone pavement) and in the Lowland fens priority habitat where they occur in enclosed agricultural lowlands.

Definition in relation to other habitat classifications

Classification Habitat types belonging to this UK BAP priority habitat M4-6 (examples in unenclosed uplands), M7-8 (all examples), M9 (examples in unenclosed uplands), M10 (examples in unenclosed uplands but not on limestone pavements), M11-12 (all examples), M14 (in unenclosed uplands), M21, M23a, M25c (in unenclosed uplands), M27 (in unenclosed uplands but not on limestone pavements), M28-29 (in unenclosed uplands), M31-38 (all examples), S3 (upland examples not very closely associated with NVC aquatic habitats), S9-10 (in unenclosed uplands), S11, S19 (upland examples not very closely associated with aquatic habitats), S27 (upland examples not dominated by Phragmites), U6 (flushed, herb-rich forms – no NVC sub-community exists to accommodate these), and non-NVC Neutral small sedge flush (examples in unenclosed upland areas). M4-12, 21, 23, 27, 31-34, 37-38, S27 and U6 are included in the Scottish Biodiversity List. Phase 1 E2, E3 and F1 (examples in unenclosed upland areas). All examples of this priority habitat which conform to the NVC UK BAP broad communities described above belong in the broad habitat - Fen, habitat marsh and swamp.

Definition in relation to legislative classifications

Classification Habitat types belonging to this UK BAP priority habitat H7140 (upland examples), H7150 (examples which are not on Habitats Directive deep peat in bog ombrotrophic habitats), H7220 (all examples) Annex I and H7230 (upland examples). Alkaline fen Alpine flush Sub-alpine flushes SNH SSSI habitat Ladder fen features Spring-head, rill and flush This priority habitat can also be part of a mosaic of two or more SSSI habitat features classed together as the Upland assemblage SSSI habitat feature.

Where is it?

The Upland flushes, fens and swamps are communities of wet habitats. These vary from:  springs, where water emerges from the ground at varying speeds from a slow trickle to a powerful gush, to  stony and soily flushes where water seeps or runs over the surface of the ground, to  fens and swamps where the water moves slowly, if at all, through deep soil.

As surface water is a product of a cool and wet climate, these communities are characteristic of the uplands. This priority habitat can occur from just above sea-level in the north and west Highlands to over 1000 m on our highest hills.

The swamps and fens tend to form mosaics with grasslands, wet woodlands, wet heaths and even blanket bogs on gentle slopes. Flushes and springs can emerge within stands of virtually any type of vegetation, including the rock habitats.

Since the wet climate is one of the defining features of the British uplands, this priority habitat is common throughout from south-west England to the northern Highlands and Islands. All the constituent plant communities occur in , though M21, M29 and M35 are mainly southern in Britain and are scarce in Scotland. The M7 Carex curta mire, M12 mire, M33 Pohlia wahlenbergii var. glacialis spring and M34 Carex-Koenigia spring are confined to Scotland. The remaining sedge mires, rush mires, springs and swamps occur also in England and Wales, though the examples at higher altitudes in the Highlands have more of the uncommon montane species than those further south.

Similar types of vegetation occur in mainland , particularly Scandinavia, the Faroe Islands and Iceland, although the Juncus effusus and J. acutiflorus mires appear to be almost confined to Britain and Ireland.

What is special about it?

Species of special conservation status recorded in this priority habitat in Scotland are listed below.

Wildlife EC Scottish and UK BAP Habitats Bio- Red Country- Common priority Directive diversity Data side Act Group name Latin name list Annex II List List (1981) common amphibians Bufo bufo y y y toad birds curlew Numenius arquata y y birds dotterel Charadrius morinellus y y birds dunlin Calidris alpina y birds golden Pluvialis apricaria y plover birds purple Calidris maritima y y sandpiper birds snow bunting Plectrophenax nivalis y y birds wood Tringa glareola y y sandpiper marsh butterflies Euphydryas aurinia y y y y fritillary mountain butterflies Erebia epiphron y y y flowering Euphrasia rostkoviana an eyebright y y y plants subsp. montana flowering yellow marsh y y y y y plants saxifrage wavy flowering meadow- Poa flexuosa y y y plants grass glaucous flowering meadow- Poa glauca y y y plants grass flowering alpine milk- Astragalus alpinus y y y plants vetch flowering cyphel Minuartia sedoides y y y plants flowering mountain Cochlearia micacea y y plants scurvy-grass flowering flat sedge Blysmus compressus y y y plants lesser flowering butterfly- Platanthera bifolia y y y plants orchid fen liverworts Leiocolea rutheana y y y y notchwort bog paw- Barbilophozia liverworts y y y wort kunzeana mammals water vole Arvicola terrestris y y y mammals red deer Cervus elaphus y round- molluscs mouthed Vertigo genesii y y y whorl snail geyer's whorl molluscs Vertigo geyeri y y y snail Schleicher`s mosses Bryum schleicheri y y y y thread-moss rugged Splachnum mosses y y y collar-moss vasculosum tongue- mosses leaved lingulata y y y gland-moss blunt-leaved mosses Pohlia obtusifolia y y y thread-moss Haworth's haworthii y y minor moths narrow- Hemaris tityus y y Wildlife EC Scottish and UK BAP Habitats Bio- Red Country- Common priority Directive diversity Data side Act Group name Latin name list Annex II List List (1981) bordered bee hawk- moths sword-grass Xylena exsoleta y y swamp Notioscopus spiders lookout y y sarcinatus spider cloud-living spiders Semljicola caliginosus y y spider

Wet habitats are protected from burning and excessive grazing, have an unstable substrate and are subject to continual disturbance from flooding and, in some cases, trampling. As a result they can be species-rich and many of them provide pockets of high floristic diversity within more uniform upland swards.

These communities can be home to rare species. For example:  In the taller sedge and rush mires species such as string sedge Carex chordorrhiza, bog sedge C. limosa, tall bog sedge C. magellanica, whorled caraway Carum verticillatum and the mosses Sphagnum contortum, S. teres, S. platyphyllum and Tomenthypnum nitens.  In the small sedge flushes, especially above the tree-line, species such as lesser tussock sedge Carex diandra, fibrous tussock sedge C. appropinquata, scorched alpine sedge C. atrofusca, sheathed sedge C. vaginata, bristle sedge C. microglochin, close-headed alpine sedge C. norvegica, Thalictrum alpinum, Bartsia alpina, brown bog rush Schoenus ferrugineus, alpine rush Juncus alpinoarticulatus, two-flowered rush J. biglumis, three-flowered rush J. triglumis, falde sedge Kobresia simpliciuscula, Teesdale sandwort Minuartia stricta, Scottish primrose Primula scotica, Saxifraga hirculus, Scottish asphodel Tofieldia pusilla and the bryophytes Cinclidium stygium, Hamatocaulis vernicosus, Barbilophozia kunzeana, B. quadriloba, Meesia uliginosa, Catascopium nigritum, Amblyodon dealbatus, Tritomaria polita, Tayloria lingulata, Calliergon trifarium, Scorpidium turgescens, Oncophorus virens, O. wahlenbergii, Orthothecium rufescens, Leiocolea gilmannii and Scapania degenii.  In the bryophyte springs and associated flushes, species such as Iceland purslane Koenigia islandica, Highland saxifrage Saxifraga rivularis, alpine foxtail Alopecurus borealis, alpine cat’s-tail Phleum alpinum, alpine hair-grass cespitosa ssp. alpina, starwort mouse-ear Cerastium cerastoides, chickweed willowherb Epilobium alsinifolium, alpine willowherb E. anagallidifolium, pale forget-me-not Myosotis stolonifera, hairy stonecrop Sedum villosum, and the bryophytes Pohlia ludwigii, Bryum schleicheri var. latifolium, B. weigelii, Philonotis seriata, Splachnum vasculosum, Anthelia juratzkana, Lophozia wenzelii, Harpanthus flotovianus, Scapania paludosa and S. uliginosa.

Upland flushes, fens and swamps provide food and shelter to many upland invertebrates, including flies such as Clinocera nivalis and Pseudomyopina moriens, beetles such as Gabrius scoticus and Elaphrus lapponicus, spiders such as Maro lepidus, and snails. These in turn provide food for -eating birds, especially in the winter where they may be the only unfrozen pieces of ground, and in spring when chicks are being fed. Notable species include red grouse Lagopus lagopus, ptarmigan L. mutus, golden plover Pluvialis apricaria, dotterel Charadrius morinellus, snipe Gallinago gallinago, curlew Numenius arquata, redshank Tringa totanus, lapwing Vanellus vanellus, dunlin Calidris alpina and snow bunting Plectrophenax nivalis. The M28 Iris-Filipendula mire is an important habitat for breeding corncrake Crex crex in the so-called ‘machair fens’ of the Outer Hebrides.

How do we manage it?

This priority habitat is maintained by a constantly high water table and in most cases light grazing. Drainage or other interference with the hydrology such as diverting springs for hydro-electric power or water supplies is damaging and can lead to the loss of the habitat. Light grazing is necessary in almost all examples – at low altitudes to prevent the development of wet woodland, and at moderate to high altitudes to prevent the overgrowth of large, competitive species which would shade out the smaller plants. Deer use upland springs and flushes as wallows; although the result looks unsightly it seems not to cause any damage in the long term and might even be necessary to maintain species diversity.

References, links and further reading

Averis, A., Averis, B., Birks, J., Horsfield, D., Thompson, D., and Yeo, M. 2004. An Illustrated Guide to British Upland Vegetation. Peterborough, JNCC http://jncc.defra.gov.uk/page-2463

Ellis, N.E. and Munro, K. 2004. A preliminary review of the distribution and extent of BAP priority habitats across Scotland. Scottish Natural Heritage Commissioned Report No.044 (ROAME No. F00NA02). https://www.nature.scot/information-library-data-and-research/information-library

Rodwell, J.S. ed. 1995. British Plant Communities. Volume 4 - Aquatic communities, swamps and tall-herb fens. Cambridge, Cambridge University Press.

Rodwell, J.S. ed. 1991. British Plant Communities. Volume 2 - Mires and Heaths. Cambridge, Cambridge University Press.

Rodwell, J.S. (Ed.) (1991 et seq.). British Plant Communities. 5 volumes: Vol. 1 (1991) - Woodlands and Scrub; Vol. 2 (1991) - Mires and Heaths; Vol. 3 (1992) - Grasslands and montane communities; Vol. 4 (1995) - Aquatic communities, swamps and tall-herb fens; Vol. 5 (2000) - Maritime Cliffs, Sand Dunes, Saltmarshes and Other Vegetation. Cambridge University Press, Cambridge. http://jncc.defra.gov.uk/page-4268

UK BAP (2008) http://jncc.defra.gov.uk/pdf/UKBAP_BAPHabitats-59- UplandFlushesFensSwamps.pdf

Usher, M.B., Bain, C. and Kerr, A. eds. 2000. Action for Scotland's Biodiversity. Scottish Biodiversity Group. Edinburgh, The Scottish Executive and The Stationery Office.

The Fen Management Handbook. 2011. Eds A. McBride, I. Diack, N Droy, B. Hamill, P.Jones, J. Schutten, A. Skinner, and M. Street. Perth, Scottish Natural Heritage. http://www.snh.gov.uk/about-scotlands-nature/habitats-and-ecosystems/lochs-rivers-and- wetlands/fen/

Common Standards Monitoring guidance http://www.jncc.gov.uk/page-2199

Countryside Survey http://www.countrysidesurvey.org.uk

National Biodiversity Network (NBN) Gateway https://data.nbn.org.uk/

Scottish Natural Heritage website: http://www.nature.scot

UKBAP information on JNCC website: http://jncc.defra.gov.uk/default.aspx?page=5155