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The Carran turlough is an extensive depression situated in the glacio-karstic landscape of the Burren region, Co. Clare, Eire. Which, during prolonged periods of rainfall, fills with water to form a lake of over 150 hectares. Normally, however, it grades from damp grassland to a thin stretch of water, known as the Castletown river. It is an important habitat, with very high biodiversity.
 

The Carran turlough in summer.  Number indicate the transect position for the vegetation & environmental data.

The Carran turlough in winter

In the north of the basin, the limestone pavement extends down to the water, forming a botanically diverse mosaic of habitats. The exposed rock surface, planed smooth during the last Ice Age, has developed pockets of acid wetland flora growing in shallow hollows. Deeper areas of soil are covered in, possibly ancient, woodland, and the turlough floor is a floristically diverse wet grassland.

Flora & Fauna

Calcifuges & calcicoles
The calcifuges, Heath Milkwort, Polygala serpyllifolia, Bog Asphodel,  Narthecium ossifragum, Butterwort, Pinguicula vulgaris and Sundew, Drosera rotundifolia can be found growing in close proximity to calcicoles such as Carline Thistle, Carlina vulgaris, Blue Moor Grass, Sesleria albicans and Yellow-wort, Blackstonia perfoliata. The edges of these peaty depressions, where the turf is mainly comprised of glaucous leaved Carnation Sedge, Carex panicea, Flea Sedge, Carex pilulifera and Black Bog Rush, Schoenus nigricans, are good sites to find Fly, Ophrys insectifera and Lesser Butterfly, Platanthera bifolia, Orchids. In late summer the very attractive Grass-of-Parnassus, Parnassia palustris, is common.  Growing from the grykes, and forming a tangle amongst the Hazel, Corylus avellana, Burnet Rose, Rosa pimpinellifolia and Wood Sage, Teucrium scorodonia is the Stone Bramble, Rubus saxatilis, a plant associated with circum-boreal northern limestones, which compensates for its limited floral display when in splendid red berry.

Ferns
The grykes at Carran harbour a wealth of ferns with Rusty-back, Ceterach officinarum, Maiden-hair Spleenwort, Asplenium trichomanes, Wall-rue, Asplenium ruta-muraria, Hart's-Tongue, Phyllitis scolopendrium, and Male Fern, Dryopteris filix-mas joined by the locally more uncommon Hard-Shield Fern, Polystichum aculeatum and Brittle Bladder Fern, Cystopteris fragilis. Maiden Hair Fern, Adiantum capillus-veneris also grows here, well away from its normal maritime cliff haunts.

Limestone pavement
The pavement is very species rich with prostrate Juniper, Juniperus communis, Cat's paw Antennaria dioica, Spring Gentian, Gentiana verna, Mountain Avens, Dryas octopetala, Limestone Bedstraw, Galium sterneri,  Squinancywort, Asperula cynanichica, Bloody Cranesbill, Geranium sanguineum, Hawkweeds, Hieracium species, and Irish Eyebright, Euphrasia salisburgensis.  Although there is little woodland around the turlough, the flora of the grykes and Hazel, Corylus avellana, scrub has a strong sylvian influence with Blue-bell, Hyacinthoides non-scripta, Ramsoms, Allium ursinum, Wood anemone, Anemone nemorosa, Goldilocks, Ranunculus auricomus, Broad leaved Helleborine, Epipactis helleborine, Cow-Wheat, Melampyrum pratense and Wood-ruff, Galium odoratum, all hinting at a former more extensive tree cover.

This relict ancient woodland influence may account for the survival here of Silver-washed, Argynnis paphia, Dark Green, Argynnis aglaja & Pearl-bordered, Boloria euphrosyne, Fritillary butterflies.

The Turlough edges
In the base of the depression the pavement gives way to a 'lawn' sloping towards the water edge.
The turf has a  variety of plants which occur in damp conditions, with many common plants such as Creeping Buttercup, Ranunculus repens and Silverweed, Potentilla anserina as well as the more unusual  Adder's Tongue fern, Ophioglossum vulgatum, Northern Bedstraw, Galium boreale, Meadow Thistle, Cirsium dissectum which are all plentiful, along with the rare Marsh Dandelion, Taraxacum palustre. The wetter zones, contain the beautiful Lesser Water Plantain, Baldellia ranunculoides with its soft pink flowers.

The Carran turlough would be a wonderful place, even without the flowers, just for the sheer variety of life. There is always something exciting here, a profusion of Spike Rushes, Eleocharis spp., Sedges, Carex spp., Horse-tails, Equisetum spp., waders, multi-coloured frogs, dragon-flies and rare moths, including  the day flying Transparent Burnet and Narrow-bordered Bee hawkmoths.

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