Yorkshire Dales Limestone IPA
Location: North of England, covering the central Pennines in the counties of North Yorkshire and Cumbria.
Grid Reference: SD 905 809
Yorkshire Dales Limestone IPA has been recognised as one of 165 Important Plant Areas in the UK.
The key features of this IPA are:
Raised bogs with growing sphagnum;
Nutrient-poor waters with Stonewort algae;
Purple moor-grass meadows;
Hard water springs;
Semi-natural calcareous grasslands, sometimes with scrub;
Calcareous rocks with crack & fissure vegetation;
Juniper scrub on heaths and calcareous grasslands
The majority of the limestone country of the Yorkshire Dales is concentrated in the uplands around Ingleborough, Malham and Wharfedale. In these areas the Great Scar Limestone was laid down on seabeds some 300 million years ago.
During the last ice age glaciers scraped away the surface exposing the natural joints in the underlying limestone rock. Slightly acidic rain dissolved these vertical joints creating the limestone clints and grikes (blocks and the crevices in between), which make up limestone pavements. The soils lying over this rock are usually very thin and of low fertility and, in combination with consistent grazing, often results in a rich diversity of lime loving grasses, ferns and wildflowers for which the limestone country of the Dales is famous.
The plants which are most commonly associated with the pavements of the Yorkshire Dales are the ferns. These may include the maidenhair spleenwort, hart’s-tongue fern, brittle bladder-fern and the nationally scarce rigid buckler-fern.
Well developed pavements that are only lightly grazed can develop vegetation on the surface of the clints. Plants which might grow here are blue moor-grass, wild thyme, limestone bedstraw, common rock-rose, bloody crane’s-bill, butterwort and birds-eye primrose.
The sheltered, shaded conditions within grikes provide ideal habitats for many woodland plants. The most abundant of these are dog’s mercury, ramsons, herb Robert and wood sorrel, but other less frequently occurring woodland species associated with limestone pavements include sanicle, wood anemone, enchanter’s nightshade, common dog violet and more rarely, herb-paris, angular Solomon’s seal, lily-of-the-valley and baneberry.
Steep, unstable and exposed cliff faces support a range of species, such as common whitlowgrass, hairy rock-cress, biting stonecrop, thale cress and the rare winter annual hutchinsia. Scree slopes below unstable cliffs also have their special plants including the prickly sedge which is critically endangered in the UK.
In parts of the Yorkshire Dales there are internationally important tracts of limestone grassland. These support some of the area’s rarest and most important habitats and species. Blue moor-grass dominates here and the thin limestone soils support a range of lime-loving plants including bird’s-foot trefoil, fairy flax, mouse-ear hawkweed, wild thyme, rock-rose, limestone bedstraw, carline thistle, small scabious, marjoram, autumn gentian, bloody crane's-bill and mountain everlasting.