Basaltic Outcrops as Centers of Diversity for Xerothermic Plants in the Sudetes Mountains (Central Europe)

Rock outcrops have promoted a high level of species diversity and provided stable microclimate for long time periods. The present study is devoted to plant natural Quaternary basaltic rocks. Chorological ecological investigations were carried out at 35 such outcrops, located within five physiogeographic units the Sudetes Mountains. focus was on 120 xerothermic taxa vascular plants: 62 strictly (steppe) Festuco valesiacae-Brometea erecti class, 58 thermophilous representing classes Trifolio medii-Geranietea sanguinei Quercetea pubescentis. Limited geographical ranges these plants are manifested by variable frequency their occurrence. Species distribution determined factors, like surface area outcrop, type rock communities developed. Basaltic in meet criterion habitat islands (inselbergs), serve as regional centers flora, refugia marginal populations relict species.