A quick glance at the Burren would leave you thinking it was just rock and little else. This, however, is a very complex ecosystem. The habitats within the Park grade into one another and often are inseparable, creating a mosaic of habitats that are hard to isolate. For example, limestone pavement is often inter mixed with calcareous grassland and hazel scrub, or ash woodland on limestone pavement. All the major Burren habitats are represented within the Park. Approximately 75% of plant species found in Ireland are represented within the habitats of the Burren. Included among these are 23 of Ireland’s 27 native orchid species.
Limestone pavement has become almost synonymous with the Burren and covers most of the National Park, although, as mentioned above, usually in a mosaic with other habitats. The pavement may be of either a smooth or shattered type.
The smooth limestone pavement areas consist of clints and grykes. The clints are the slab like flat surface areas of the pavement and the grykes are the fissured cracks that dissect the clints. The grykes provide shelter for the soil to accumulate and also shelter from the wind. The thin soils that accumulate in the grykes provide just enough anchorage and nutrients to host a large diversity of plant species. Within the grykes, you can find shade tolerant plants such as ivy and hearts- tongue fern but also a variety of other species such as Bloody Crane’s-bill, Wall Lettuce, Wall-rue and Rue-leaved Saxifrage to name just a few. Also found eking out an existence in the grykes are woody plants such as Ash, Blackthorn, Holly, Buckthorn and Whitethorn (Hawthorn). These are stunted like a bonsai due to the lack of space for the roots and also due to a lack of nutrients, water and soil. The wind, along with grazing, also plays a part in keeping these plants and trees at a low level, searching out shelter at ground level.
Photo: John Lalor
On the shattered limestone, grykes are less frequent and plant life therefore is sparse, however if you look close many species thrive in these conditions. Burnet Rose, Wood Sage, Dark Red Helleborine, Hazel, Juniper, Yew and Blackthorn are all making this habitat their own. Again wind, soil and water are all limiting factors in their growth. Goats especially, also graze Yew and Ash. Another anomaly of these pavement areas is the ability of woodland plants like Wood Sage to thrive out in the open without any shade.
Calcareous grassland is found on the terraces of the mountains and between the limestone pavement where there is also a thin layer of soil and on glacial deposits throughout the Burren. These calcareous grasslands host an extraordinary composition of flora. It is the calcareous grasslands, found in a mosaic with limestone pavement, which attract botanists from all over the world because nowhere else in the world is this precise mixture of plants found growing together.
It is not so much the rarity of the species found in these habitats, as the unusual and unique mixture of species. Arctic-Alpine plants are found growing side by side with Mediterranean plants, and at latitudes and altitudes not expected. For example, Mountain Avens and Spring Gentians, these are Arctic-Alpine plants normally found either in Arctic regions or high up in the Alps. In the Burren they are found growing from sea level up to the highest peak of 317 metres. Many Mediterranean species like the Dense-Flowered Orchid and Maidenhair Fern are found co-existing with the Arctic-Alpine plants in this habitat. Lime-loving plants (calcicole) and acid-loving plants (calcifuge) also grow side by side. For example Heather, Lousewort and Tormentil grow interspersed amongst orchids, Bloody Crane’s-bill and Cowslips.
This is a common habitat within the Burren. It occurs anywhere there is enough soil and shelter, large tracts of the southern Burren are completely blanketed with hazel scrub. The height of the scrub varies from knee height to 5 meters. The hazel provides shelter for many species of fauna (Badgers, Pine Martens, Foxes, Red Squirrels, mice, shrews, etc.) and also for plant species such as Blackthorn, Whitethorn, Brambles, and tree species such as Ash, Holly and Willow. Scrub represents a stage in the succession to woodland, such as Ash, Pine or Oak woodland.
In spring and summer the hazel canopy allows enough light in to support the development of a rich ground flora. These woodlands in early spring are carpeted with Bluebells, Wild Garlic, and Wood Anemone. Later in the summer Helleborines and other typical woodland flora are abundant.
The Hazel scrub provides extensive suitable habitat for many different fungi and lichens, some of which are extremely rare. These rare species, combined with other more common fungi, create an extremely diverse community of micro-organisms, amongst the most important in the British Isles.
Mature deciduous woodland is not common within the Park, but there are some very good examples of Ash/Hazel woodland, Pine Forest and Oak/Ash Woodland. Scrub will turn to mature deciduous woodland with time, given adequate depth of soil and shelter. These woodlands tend to be found in dry valleys that have steep sides where the wind sweeps across the top, or in the shelter of cliffs. To the south east of Mullaghmór is an excellent example of Scots Pine woodland and close by is some Oak woodland. Behind Lough Gealáin on the western side of Mullaghmór is a dry valley with a fine example of Ash woodland. These woodlands often contain other native tree species; Wych Elm, Spindle, Downy Birch, Holly, Willow, Crab Apple, Rowan, Yew and Aspen. These woodlands are also fine habitats for the lichens and fungi found in the similar but less developed Hazel scrub areas.
The word Turlough comes from an Irish word “Tuar loch” meaning disappearing lake. Turloughs are areas that flood in winter or during times of heavy rain. They are fed from groundwater, either through swallow holes or through cracks in the lakebed.
The turloughs in the National Park generally have very low nutrient levels and their oligotrophic status means that they are of great botanical interest. Their varied and interesting vegetation consisting of a mixture of aquatic plants, such as various species of stonewort and pondweed, and terrestrial species which are tolerant of submersion. This leads to a characteristic zonation of the vegetation of a turlough, some species having adapted to survive long spells inundated with water, therefore growing low down in a turlough while others require short periods of flooding therefore growing on the high flood level. The rare and protected species Shrubby Cinquefoil is one of the plants found in the high flood zone, also found is the dark moss Cinclidotis fontinaloides.
Photo: Margaux Pierrel
In certain areas that are liable to periodic or seasonal flooding, for example around the margins of Lough Gealáin and in the townland of Ballyeighter, a calcareous Peat has developed. These areas support a rich fen vegetation which is characterised by such species as Black Bog-rush, Bog Thistle, Lesser Spearwort, Purple Moor-grass, Jointed Rush, Bog Myrtle, Bogbean, Orchid species such as Dactylorhira incarnata, D. majalis, and Ophrys insectifera, Grass of Parnassus, Devil’s-bit Scabious, and various sedge species such as Carex nigra, C. rostrata, C. lepidocarpa, C. hostiana. Mosses such as Scorpidium scorpioides, and Calligeron cuspidatum are common in the moister areas. Where the water level is higher, Saw Sedge (Cladium mariscus), and Common Reed can predominate. The Burren has quite extensive and intact areas of fen. While similar wetlands have been lost through drainage elsewhere in the country.
There are a number of lakes, both semi-permanent and permanent, within the National Park, some are part owned and some are fully owned by the National Park. Included either partially or fully within the Park are Lough Gealáin, Travaun Lough, Coolorta Lough, Coolreash Lough, Aughrim Lough, Ballyeighter Lough and Lough Bunny. Some of these lakes behave partly as Turloughs being fed from the ground water through springs and sink holes on their peripheries. They vary from Lough Bunny where the water level barely changes to Travaun Lough which is nearly empty in the summer. In the parts of the lakes that dry out in the summer the vegetation can resemble that of Turloughs. In areas of deeper water aquatic plant communities occur and in the shallow water areas semi-aquatic communities occur. Stands of Reed Canary-grass, Saw Sedge and Common Reedmace are found in the shallower areas, with Pondweed species and Water-lilies in the deeper water. Stands of Charophytes (Nitella and Chara species) are found in both the deepest water and in the shallower areas.
Photo: John Lalor
The most extensive area of reed swamp and semi-aquatic vegetation occurs in the Ballyeighter Lough area. This forms part of an extensive wetland encompassed in the catchment of the upper Fergus River and is probably the most important oligotrophic calcareous system of freshwater lakes in Western Europe.
Cliffs and Scree
The architecture of the Burren uplands is that of terraces divided by cliffs, the debris that has fallen from these cliffs forms small scree areas. The vegetation on the cliffs is almost identical to that on the limestone pavement areas. Trees however that get a foot hold on the cliffs often grow bigger than their counterparts on the flat pavement, this is because grazers cannot reach them. On the southern slopes on Mullaghmór some large Yew trees can be seen growing out of what seems to be pure rock.