Effects of roads on adjacent plant community composition and ecosystem function: An example from three calcareous ecosystems

► A transect study assessed the effects of roads at three calcareous grasslands. ► Substantial areas experienced NOx above the critical level of 30 μg m−3. ► Copper, zinc and lead concentrations approximately doubled in roadside soils. ► Roads may also disrupt natural drainage and increase the pH of soils. ► Plant compositional changes were found in relation to roadside proximity.