Title
Irish hazel-ash forests and scrub (Fraxinus excelsior, Corylus avellana), alternating with Sesleria albicans-dry grasslands and Dryas-heaths on extremly shallow calcareous soils
Geographical distribution
Country/territory
Ireland: west Ireland (Burren region), Aran islands; Great Britain: very small-scaled in contact to F29 (not shown on the map)
area frequency
4 polygons.
Scientific names of main plant communities and their most common synonyms (with author citation)
a) Corylo-Fraxinetum neckerotosum Kelly & Kirby 1982, b) Prunetalia spinosae Tüxen 1952; c) Dryas octopetala-Hypericum pulchrum-Assoziation Ivimey-Cook & Procter 1966, in complex with Mesobromion-poor grassland, d) Arctostaphylo-Dryadetum Ivimey-Cook & Procter 1966.
Structural feature of the main community(ies) (layers, life-forms, etc.)
A complex consisting of ash-hazel shrub forests, heaths, shortgrass meadows and vegetation-free limestone "pavement" or rock. This forest is mostly a shrub-formed variant of unit F29. The tree layer seldom reaches a height of 8 m, and usually remains much shorter and is formed from ash and hazel. The lianas remain for the most part in the herb layer and cover the rocks. In open areas there are species-rich, low-growing (seldom > 10 cm) shortgrass meadows and rocky heaths that are closely interdigitated. Here Dryas octopetala and Sesleria albicans dominate. Together with Festuca rubra, Carex flacca, Briza media, Calluna vulgaris and calciphilous mosses they form a more or less closed soil covering above the furrowed limestone. In the vertical rock fissures Asplenium scolopendrium and thorn shrubs grow, particularly Rosa pimpinellifolia.
Dominant and most frequent species in different layers
Tree layer
Fraxinus excelsior, Corylus avellana
Shrub layer
Corylus avellana; in rock crevices b) Rosa pimpinellifolia, Prunus spinosa, Rhamnus cathartica, Rubus fruticosus agg., Potentilla fruticosa
Lianas
a, b) Hedera helix (creeping, soil covering)
Herb layer
c) Sesleria albicans, Dryas octopetala, Carex flacca, Thymus praecox, Succisa pratensis;
d) Calluna vulgaris, Festuca rubra, Briza media, Antennaria dioica, Hieracium pilosella, Lotus corniculatus, Galium verum, Hypericum pulchrum, Asperula cynanchica, Gentiana verna, Erica cinerea; in higher altitudes on tops e) Dryas octopetala, Sesleria albicans, Empetrum nigrum, Arctostaphylos uva-ursi, Juniperus communis
Moss layer (incl. lichens)
c) Breutelia chrysocoma, Neckera crispa, Tortella tortuosa;
d) Ctenidium molluscum, Dicranum scoparium, Scapania aspera
Diagnostically important species
Fraxinus excelsior; Corylus avellana; Dryas octopetala, Sesleria albicans, Geranium sanguineum, Helianthemum oelandicum subsp. incanum, Breutelia chrysocoma, Neckera crispa, Tortella tortuosa; Calluna vulgaris, Erica cinerea; Arctostaphylos uva-ursi, Empetrum nigrum
Ecological variants
Very differing plant communities occur depending on soil depth and lime content, altitude, exposure and degree of waterlogging.
Geographical variants (geogr. differential species)
No details
Natural accompanying vegetation (most important units in complex with the name giving mapping unit, scientific names)
Prunetalia spinosae scrub; Frangula alnus-Rhamnus cathartica scrub in temporarily waterlogged basins; fen communities in wet hollows; fern-rich rock fissure communities.
Adjoining climax and permanent vegetation (with numbers of mapping units)
coastal rocky heaths (E11), mixed oak-ash forests (F29), brown mires (S24), alder-ash forests (U23).
Land use, substitute communities
forestry (substitute communities, plantations of economic tree-species, scrub)
Unsuitable for forestry.
grassland (meadows, pastures, herb-rich communities)
The major form of land usage is grazing by sheep and cattle: Antennarietum bibernicae Br.-Bl. & Tx. 1952 and Centaurio-Cynosuretum Br.-Bl. & Tx. 1952.
arable land (characteristic weed communities)
Small patches of arable land in the environs of settlements, manually worked over, with an interesting weed flora including Centaurea cyanus and Lolium temulentum.
settlements (typical ruderal vegetation)
---
Site conditions of the mapping unit
Landscape type, geomorphology
Flat to stepped karst landscape
Altitudinal belt and/or altitudinal range
lowland to submontane; 0-330 m
Geology (bedrock)
limestone (Carboniferous)
soil type, also the depth of fine textured earth (soil), stone content; (international nomenclature)
protorendzines, shallow rendzines; (leptosols consisiting of limestone)
soil texture
loamy-grouany to rocky
soil moisture, water balance
fresh to dry
soil reaction
neutral to weakly acidic (depending on the cover of fine soil)
soil fertility
oligo-mesotrophic with a high content of lime
Climate incl. local climate
climate type (following Walter & Lieth)
V(VI)1, VI(V)1
average annual temperature
8-10 EC
average annual precipitation
1200-1400 mm
average temperature of the warmest month
14-16 EC
average temperature of the coldest month
4-6 EC
local climate or other climatic peculiarities
Over 175 rain days per year, frequent formation of clouds, strong winds.
Importance for nature protection
Present state and development trend of natural vegetation (degree of endangerment)
Mainly semi-natural vegetation due to long-standing grazing, and natural vegetation is preserved in only small patches: on rocks, in rock fissures and basins. Natural succession would entail spreading of the forest vegetation and a reduction in shortgrass meadows and heaths.
endangered communities, species worthy of protection in natural vegetation
The whole complex is worthy of protection in regard to its remarkable species-richness and in regard to the co-occurrence of species from different geographic regions with different demands on their habitat: e. g. Neotinea maculata, Adiantum capillus-veneris, Dryas octopetala, Gentiana verna.
causes of endangerment
Grazing, clearing of the scrub, fertilization of the grass and heathland, flattening of the relief-rich karst landscape, removal of rocks.
required measures for protection and restitution
Cessation of the above-mentioned measures; preservation of traditional forms of land usage, in some areas with valuable shortgrass meadows and heaths, and in others cessation of usage.
Localities of representative stands (loci typici) with state of protection
of the natural vegetation
Ireland: Slieve Carron Nature reserve, Burren National Park.
of characteristic substitute communities worthy of protection
Calcareous shortgrass meadows managed in traditional ways and heaths in Blackhead near Poulsallagh, Cappanawalla-, Gleninagh- and Moneen-mountains.
Most important references (author, year)
Ivimey-Cook & Proctor 1966; Kelly & Kirby 1982; Kirby 1981; McGough 1984; Rodwell (Ed.) 1991a
Compiled by
J.R. Cross
