Study area and focal species of edaphic islands
We selected 20 rocky (granite or syenite) outcrops occurring in the
southern Czech Republic, located at elevations around 450 m a.s.l.
(centroid: 49°14’12”N, 15°57’26”E; Figure 1). These outcrops (edaphic
islands) are scattered across approximately 100 km2and embedded in a landscape matrix of arable land. Their average area is
~2,912 m2 (min = 361
m2, max = 14,115 m2). The regional
macroclimate is temperate (mean annual temperature: 6.5–8°C, annual
precipitation: 500–550 mm; Tolasz, 2007), characterized by a marked
temperature and precipitation seasonality (Doležal et al., 2021). The
vegetation growing on these gently dome-shaped outcrops (maximum
elevation ~5-10 m compared to the surroundings) is
acidophilous dry grassland.