Sparsely vegetated weathered rock and outcrop habitats

Rocks and outcrops colonised by pioneer communities, especially of [Crassulaceae]. Vegetation of the alliance [Sedo-Scleranthion biennis]. Substrates are mostly siliceous, occurring in the upland and montane levels of the nemoral zone. The communities are dominated by succulent [Sempervivum], [Jovibarba] and [Sedum] species accompanied by [Silene rupestris], [Erophila verna], [Scleranthus polycarpos], [Veronica fruticans], [Thymus praecox ssp. polytrichus], [Viola tricolor ssp. saxatilis], by small crucifers, lichens and mosses [Polytrichum piliferum] and [Racomitrium canescens].