In 2004, soil properties and the species composition of vascular plants and lichens were studied at five sites in a former zinc and lead mining region (Olkusz region, southern Poland). The sampled sites, four reclaimed by planting trees differed in age (5, 15, 30, 35 years old), and one spontaneously vegetated (100 years old). The sites were similar in soil structure and chemical composition. These were skeletal soils poor in N and P, and rich in Ca, Mg, Zn, Pb and Cd. The 100-year vegetation which has developed there spontaneously is represented by grasslands formed mostly by species of open, dry, warm, calcareous and metalliferous habitats, with a numerous group of lichens. On sites with planted trees, the herb layer plants appeared as the result of spontaneous colonization. In the herb layer of younger sites there were species typical of spontaneously developed grassland. Older sites harbored fewer grassland species but also included shade-tolerant meadow species. Expansion of trees caused the disappearance of species characteristic of metalliferous waste habitats. Though tree planting accelerates the formation of plant cover in post-mining areas, it is not conducive to the maintenance of the specific composition of local plant species. Spontaneous development of local vegetation seems an appropriate way to rehabilitate at least part of post-mining areas with regard to the maintenance of the vegetation typical for the metalliferous soils. Islands of such vegetation increase the biodiversity of degraded areas.