Siliceous rock with pioneer vegetation (Sedo-Scleranthion, Sedo-albi Veronicion dillenii)
Pioneer communities of the Sedo-Scleranthion or the Sedo albi-Veronicion dillenii alliances, colonizing shallow soils of siliceous rock surfaces and rubble. As a consequence of the dry conditions this open patchy vegetation is characterized by mosses, lichens and Crassulaceae.
Exposed siliceous rock and rocky ledges with species-rich siliceous lichen communities are extremely endangered, at least in Central Europe, and are also included.
Notes on habitat mapping
The precondition for assignment to this habitat type is the presence of vegetation of the syntaxa given above.
The entire area of exposed siliceous rock that is free of woodland and scrub should be included if considerable sections host the relevant vegetation. Secondary rock surfaces (e.g. quarries, rocky slopes cut for road corridors etc.) are included provided they host the relevant vegetation. However, chasmophytic vegetation on buildings is not included.
Comments
Xero-thermophile swards on rocky outcrops (Seslerio-Festucion pallentis) with characteristic species: Festuca pallens, Melica ciliata, Dianthus gratianopolitanus, Erysimum crepidifolium, Erysium odoratum, Alyssum montanum ssp. montanum, should be included in delimiting sites, even though they are not explicitly named in Annex I.