Lowland to montane temperate and submediterranean genistoid scrub

A few meters high scrubland, dominated by species of the family Fabaceae (Leguminosae),  specifically species of the genera Cytisus, Ulex, Adenocarpus, Genista and/or Retama. The habitat occurs in the temperate, submediterranean and mediterranean region, where it is mainly found on sunny, dry, nutrient-poor, acidic soils, but exceptionally also grows on more base-rich soils. It is in most cases a secondary habitat, forming a stage in the succession from grassland or heathland towards (Quercus) forests and occurring as mantle vegetation along forests. The potential vegetation in the areas of this broom dominated habitat are forests dominated by Quercus pyrenaica, Q. suber, Q. rotundifolia and in more humid areas Q. robur, Q. petraea and Fagus sylvatica. The habitat is associated with agro-pastoral landscapes, and in such environment it may form a threat to heathlands and grasslands, as the shrubs encroach after abandonment of traditional management. Broom species easily germinate in fallow lands on nutrient-poor, mineral soils, where they have good competitive conditions because of the root nodules, containing bacteria that capture atmospheric nitrogen (Rhizobacteria). In Portugal rye cultivation became the major driving force behind the evolution of broom fields and – to a lesser extent – also triggered the development of other vegetation.

Cytisus scoparius may also dominate ruderal sites, like along roads, in dry riverbeds, on cultivated fields, in logged forests or on burned sites. In rocky areas on shallow soils, also primary habitats of this type may be found. In Spain, Portugal and France genistoid scrub can also grow as post-fire vegetation.

In Northwest and Central Europe this is a relatively species poor type, mainly dominated by Cytisus scoparius and – in the Atlantic regions – Ulex europaeus, and with Orobanche rapum-genistae as a characteristic species of the Cytisus scoparius scrub. Further south the type becomes more diverse. In southern Italy (Sicily and Calabria) a community of Adenocarpus brutius (= Adenocarpus complicatus subsp. brutius ) and Cytisus scoparius with many endemics (including Viola aethnensis subsp. messanensis) occurs as secondary vegetation in relatively acidic, mesophilous sites where Fagus sylvatica or Quercus ilex forests are the climax.  In central Italy Adenocarpus complicatus subsp. complicatus forms scrub formations.

The highest diversity however is found on the Iberian Peninsula, where a broad range of high, genistoid shrubs may dominate, depending on the geographical region, elevation and soil conditions. Examples of such shrubs are Cytisus multiflorus, Cytisus striatus (subsp. striatus and subsp. eriocarpus), Cytisus bourgaei (= C. scoparius subsp. bourgaei), Genista cinerescens, Genista florida, Genista hispanica subsp. occidentalis, Genista polyantha, Adenocarpus argyrophyllus, Adenocarpus telonensis, Retama monsperma and Retama sphaerocarpa. These communities in Spain and Portugal are ranked under various denominations such as retamal (dominated by Retama or Adenocarpus species), piornal (Genista-dominated) and escobonal (large brooms, for instance Cytisus).

Almost all communities of the habitat are grouped in the class Cytisetea scopario-striati, although sometimes Cytisus scoparius and Ulex europaeus also participate in the Calluno-Ulicetea or in the Rhamno-Prunetea (the analogue mantle-scrub on richer soils). For the communities in the southeastern Balkan the assignment to classes and alliances has not been worked out yet.

In several other habitat types genistoid shrubs may become dominant. In Atlantic coastal dunes scrub with Cytisus scoparius and Ulex europaeus may be found, but those are part of habitat ‘Atlantic dune scrub’ (B1.6a). Individual shrubs of these two species may grow in a heathland or matorral, for example Ulex europaeus forma maritimus and Cytisus scoparius subsp. maritimus in heathlands on rocky coasts; in such cases the communities should be considered as part of those heathland or matorral habitats. Only if the shrubs form a relatively closed and relatively high community, the habitat type F3.1c is present. In (montane to) subalpine and oromediterranean belts of mountains Cytisus oromediterraneus (=C. purgans) and Echinospartum species form (relatively low) scrub, but those communities (equivalent to HD Annex 1-type 5120) are part of the Oro-Mediterranean habitat type F7.4a (Western Mediterranean mountain hedgehog-heath). The relatively low scrub dominated by Genista hispanica subsp. occidentalis, classified in the class Festuco hystricis-Ononidetea striata, also is considered part of F7.4a.

Indicators of good quality:

The habitat tends to develop a high and relatively closed structure, while trees are absent. However, often the more open patches, mosaics with other habitats, have the highest biodiversity of plant species and animals. Indicators of good quality are:

·      Relatively open scrubland in mosaic with other types;

·      Presence of endemic shrub species;

·      Presence of Orobanche rapum-genistae (Northwestern Europe);

·      Absence of trees.

Synthesis of Red List assessment

Confidence in the assessment

Pressures and threats