IBEROATLANTICA

Description

Short (<1 m) lowland heaths on acid, leached soils, eroded by winter rains after human deforestation, impoverished and thinned, all of which reduces their capacity to store water and may occasionally lead to severe drought.

Protection

Protected under the code 4030 ("European dry heaths") by the EU Habitat Directive (certain coastal stands might qualify as the prioritary 4040*["Dry Atlantic coastal heaths with Erica vagans"], but, judging by the definition in the official Manual, not those topping sea-cliffs right above N316, as it has been generally but inappropriately accepted).

Floristic Composition

Frequent species

Ulex minor aggr. 85%, Erica cinerea 80%, Calluna vulgaris 74%, Daboecia cantabrica 69%, Agrostis curtisii 65%, Potentilla erecta 60%, Erica vagans 53%, Helictotrichon thorei 46%, Pteridium aquilinum 45%, Cirsium filipendulum 27%, Erica ciliaris 26%, Helictochloa marginata 24%, Danthonia decumbens 24%, Ulex europaeus aggr. 22%, Agrostis capillaris 22%, Serratula tinctoria 22%, Glandora diffusa 21%, Molinia caerulea 21%, Brachypodium pinnatum 20%, Erica tetralix 20%, Glandora prostrata 16%, Potentilla montana 15%, Erica umbellata 15%, Polygala vulgaris 15%, Polygala serpyllifolia 15%, Arenaria montana 14%, Halimium alyssoides 14%, Vaccinium myrtillus 14%, Avenella flexuosa 13%, Stachys officinalis 13%, Simethis mattiazzii 12%, Scilla verna 12%, Carex pilulifera 12%, Carex binervis 11%, Lotus corniculatus 11%, Hypochaeris radicata 11%, Erica mackayana 11%, Hypericum pulchrum 11%, Galium saxatile 9%, Genista tridentata 9%, Viola riviniana aggr. 9%, Festuca rubra 9%, Teucrium scorodonia 8%, Erica arborea 8%, Quercus pyrenaica 8%, Jasione montana 8%, Pilosella officinarum 7%, Blechnum spicant 7%, Quercus robur 7%, Asphodelus albus 7%, Euphorbia polygalifolia 6%, Rubus ulmifolius 6%, Anthoxanthum odoratum 6%, Scorzonera humilis 6%, Gentiana pneumonanthe 6%, Neoschischkinia truncatula 6%, Cruciata glabra 5%, Genista micrantha 5%, Carex flacca 5%, Pedicularis sylvatica 5%, Erythronium dens-canis 5% view more...

Indicator species

Ulex minor aggr. 0.83, Erica cinerea 0.74, Daboecia cantabrica 0.63, Agrostis curtisii 0.6, Potentilla erecta 0.5, Calluna vulgaris 0.49, Helictotrichon thorei 0.42, Erica vagans 0.39, Erica ciliaris 0.25, Cirsium filipendulum 0.25, Pteridium aquilinum 0.24, Danthonia decumbens 0.21, Serratula tinctoria 0.21, Molinia caerulea 0.19, Helictochloa marginata 0.16, Polygala serpyllifolia 0.14, Agrostis capillaris 0.13, Potentilla montana 0.13, Glandora diffusa 0.13, Erica tetralix 0.12, Glandora prostrata 0.11, Stachys officinalis 0.11, Polygala vulgaris 0.11, Scilla verna 0.11, Carex pilulifera 0.11, Erica mackayana 0.11, Brachypodium pinnatum 0.1, Erica umbellata 0.1, Carex binervis 0.1, Simethis mattiazzii 0.09, Arenaria montana 0.09, Hypericum pulchrum 0.09, Hypochaeris radicata 0.07, Halimium alyssoides 0.07, Lotus corniculatus 0.06, Scorzonera humilis 0.05, Festuca rubra 0.05, Euphorbia polygalifolia 0.05, Asphodelus albus 0.05, Gentiana pneumonanthe 0.05, Pilosella officinarum 0.05, Pedicularis sylvatica 0.05, Galium saxatile 0.05, Viola riviniana aggr. 0.04, Laserpitium prutenicum 0.04, Anthoxanthum odoratum 0.04, Erythronium dens-canis 0.04, Cuscuta epithymum 0.04, Blechnum spicant 0.03, Jasione montana 0.03 view more...

Phytosociology

Angelico pachycarpae-Ulicetum maritimae
Arctostaphylo crassifoliae-Daboecietum cantabricae
Cirsio filipenduli-Ericetum ciliaris
Cisto salviifolii-Ulicetum humilis
Daboecio cantabricae-Ulicetum gallii
Erico tetralicis-Ulicetum gallii
Gentiano pneumonanthes-Ericetum mackaianae
Halimio alyssoidis-Ulicetum breoganii
Halimio umbellati-Daboecietum cantabricae
Sileno maritimae-Ulicetum humilis
Ulicetum latebracteato-minoris
Ulici breogani-Ericetum mackaianae
Ulici europaei-Ericetum cinereae
Ulici europaei-Ericetum vagantis
Ulici gallii-Ericetum ciliaris
Ulici humilis-Ericetum vagantis

Relations with other habitat types

These heathlands are mostly interpretable as a dysclimax of the unit T1Bx. In the northernmost areas, cool and cloudy summers keep the organic litter permanently wet, enabling transitions towards S412 and even Q12x. Since, for geographic reasons, EUNIS would include some of the heaths in this unit in its S423 and others in S424, such units are inconsistent with our results and a new regional umbrella level IV unit is in order. In more inland, drier-summer, submediterranean areas, they transition towards S42y.

S42x

Regional distribution

The most likely original position of this shrubland, as revealed by the tiny, very dispersive seeds of Erica and its massive flowering, seen from afar, were scattered steep siliceous ridges where trees couldn't stand, soils were heavily leached by rains and wind in winter and, in summer, very dry as a consequence of their thinness and, hit by lightning, exposed to episodic spontaneous fires. All this set the selective pressures leading to these short, profusely flowering, ligneous, evergreen, small-leaved, tiny-seeded, resprouting shrubs and their characteristic fungal root partnership with lignolytic fungi. Anthropic deforestation through fire, initiated some 6000 years ago but aggravated around 1000 BC, eliminated taller competitors and chronically impoverished soils, giving heaths an unexpected advantage and inverting the ancient picture: the original shrubby islands became the new matrix and forests were relegated to isolated pockets. In recent decades, heathlands in coastal areas have experienced a substantial regression, replaced by industrial pine or eucalyptus plantations or, in flat areas suitable for mechanised agriculture, by fodder crops or artificial meadows, plowed and improved with synthetic fertilisers. Heathlands in S42y, for mutually reinforced climatic, topographic and socioeconomic reasons, are less affected by these regressive trends.

Known occurrences and potential area of occupancy of the habitat type in the study region.

S42x Atlantic Erica-Ulex heaths