The Vegetation of Turlough Basins

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Turloughs are generally surrounded by open limestone pavement, scrub woodland or pastureland.
 
The extent of the flood level is often marked by the presence of the black turlough moss - Cinclidotus  fontinaloides, which covers walls, rocks or tree branches.
Fontinalis antipyretica is a moss that is more tolerant of submergence and replaces the black turlough moss further into the turlough basin.

The vegetation within the basin is usually comprised of a herbaceous sward.  The vegetation communities of turlough basins form identifiable zones which are largely dependent on the following factors and also on a combination of all three:

The depth and duration of flooding delimit plants that are intolerant of regular submergence.  In deeper zones the soil is bare following subsidence and is subsequently colonised by ephemerals such as Rorippa islandica and Limosella aquatica.  In turloughs where the soil is freely draining the vegetation is dominated by ruderals such as Plantago lanceolata and Rumex spp. Where drainage is impeded by the clogging of swallow holes or by the deposition of marl, peat build-up is encouraged and the vegetation is dominated by sedges and rushes.  Heavy grazing results in the removal of flood tolerant scrub such as Salix spp.  These influences result in a mosaic of vegetation zones that are not necessarily at similar levels in different basins.

Many plants that are not aquatic in nature survive several months complete submergence e.g. Lotus corniculatus, Agrostis stolonifera and Ranunculus repens although in some species  such as Potentilla anserina above ground parts die-back during the inundated period.

A List of Recognisable Vegetation Types (after Goodwillie, 1998)

The following list of turlough plant communities is derived from probably the most comprehensive survey of turlough vegetation to date.  Increasing numbers relate broadly to increasing depth of inundation.  The sequence of letters relate to community development on differing substrate or communities subjected to differing grazing intensities as indicated in the text.
 
 
1A.  Dry woodland: Fraxinus excelsior, Euonymus europaeus, Quercus rober, Glechoma hederacea, Festuca gigantea, Moehringia trinervia.  Not flooded in every year or for only a few weeks.

 
 
2A.  Turlough scrub: flooded woodland of Rhamnus cathartica, Prunus spinosa, Crataegus monogyna, Virburnum opulus, Solanum dulcamara, Rubus caesius.  Litter of dead plant material enriches the soil.

 
 

2B.  Flooded pavement: exposed rock often with Frangula alnus, Rhamnus cathartica, Potentilla fruticosa, Sedum acre, Cladium mariscus and Schoenus nigricans locally.

 
 
2C.  Limestone grassland: Dryish sites with Festuca rubra, Achillea millefolium , Galium verum, Prunella vulgaris, Filipendula vulgaris.

 
 
2D.  Lolium grassland: Lolium perenne, Poa trivialis, Bellis perrenis, Leontodon autumnalis, Cirsium arvense. Includes intensive fields of pasture and sometimes much Rumex spp.

 
 
2E.  Damp grassland: Grazed fields with low nutrient input. Phleum pratense, Carex hirta, C. distcha, Festuca pratensis, Elytrigia repens, Rumex acetosa, Cardamine pratensis. 3A.  Sedge heath: Closely grazed nutrient-poor sites with good drainage and sometimes some seepage. Danthonia decumbens, Molinia caerulea, Potentilla erecta, Nardus stricta, Festuca arundinacea, Deschampsia cespitosa.

 
3B.  Carex hostiana / Molinia: Nutrient-poor fen, often on skeletal limestone. Carex panicea, C. hostiana, C. flacca, Molinia caerulea, Succisa pratensis, Cirsium dissectum.

 
3C.  Tall herb: Ungrazed, nutrient-rich sites. Carex disticha, C.hirta, Phalaris arundinacea, Filipenda ulmaria, Lysimachia vulgaris, Rorippa palustris, Polygonum hydropiper, Vicia cracca.

 
4A. Potentilla reptans / Viola canina: Species-rich, grazed community with Potentilla reptans, Filipendula ulmaria, Galium boreale, Viola canina, Salix repens, Lotus corniculatus, Ophioglossum vulgatum.

 
4B. Potentilla reptans / Carex nigra: species-poor, Potentilla reptans, P. anserina, Mentha aquatica, Carex nigra, Ranunculus repens, Litorella iniflora, Viola persicifolia.

 
4C.  Dry Carex nigra: Carex nigra, Phalaris arundinacea, Pontentilla anserina, Plantago lanceolata, Ranunculus repens, Rumex crispus.  Relatively firm in summer. 4D.  Wet Carex nigra: peaty substrate, slow to dry out with Carex nigra, Eleocharis palustris, Juncus articulatus, Caltha palustris, Senecio aquaticus.

 

5A.  Floodgrass: long-lasting pools that eventually dry out. Glyceria fluitans, Eleocharis palustris, Veronica catenata, Ranunculus trichophyllus, Rorippa amphibia, Apium inundatum.

 
5B.  Polygonum amphibium: Nutrient-rich sites with Polygonum amphibium, P. hydropiper, Carex vesicaria, Lythrum salicaria, Alopecurus geniculatus.

 
6A.  Baldellia / Littorella: on marl or peat. Baldellia ranunculoides, Scorpidium scorpioides, Potamogeton gramineus, Eleocharis multicaulis, Eleogiton fluitans, Littorella uniflora.
6B.  Eleocharis acicularis / Limosella: transitory vegetation on mud. Eleocharis acicularis, Limosella aquatica, Lythrum portula, Rorippa islandica, Polygonum minus, Chenopodium rubrum.

 
7A.  Peaty Carex nigra: Carex nigra, Menyanthes trifoliata, Equisetum fluviatile, Juncus articulatus, Lythrum salicaria.
Close to summer water table.		 7B.  Schoenus / Cirsium dissectum: fen peat layer with Schoenus nigricans, Cirsium dissectum, Molinia caerulea, Achillea ptarmica, Parnassia palustris.

 
8A.  Oenanthe aquatica / Hippuris: in ponds, springs and ditches within turloughs, Apium nodiflorum, Nasturtium officinale, Rorippa amphibia, Hippuris vulgaris, Oenanthe aquatica, Sparganium spp., Nymphaea alba.

 
 
8B.  Potamogeton / Elodea: shallow semi-permanent water with Potamogeton crispus, P. berchtoldii, P. pectinatus, Elodea canadensis, Myriophyllum spicatum, Ceratophyllum demersum.
8C.  Schoenoplectus / Phragmites: In water, Schoenoplectus lacustris, Phragmites australis, Equisetum fluviatile, Ranunculus lingua, Carex rostrata.
8D.  Magnocaricion: ungrazed sites, damp in summer. Carex elata, C. rostrata, C. vesicaria, some Phalaris arundinacea or Phragmites australis. Mesotrophic.

 
8E.  Cladium mariscus: Species-poor stands of Cladium with scattered Phragmites australis, Carex lasiocarpa, Potamogeton coloratus. Nutrient-poor. 

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