Investigations were carried out in patches of Molinietum caeruleae meadows dominated by small meadow species (patch I), characterised by prevailing large-tussock grasses (patch II), and overgrown by willow shrubs and bordered by trees (patch III). In each patch, 15 circular gaps with a radius measuring 30 cm were artificially created by the removal of the plant canopy and litter layer. Subsequently, each gap was divided into a central part, with a radius of 20 cm, and a peripheral part. Light intensity and soil temperature were greater in the central parts of these openings than in their peripheries, while ground humidity presented the inverse tendency. Despite heterogenous environmental conditions in the gaps, the total numbers of species/seedlings noted in their central and peripheral parts did not differ significantly. The majority of taxa recruited similarly over the entire surface of openings; a much lower number of species colonized primarily the central parts of gaps; the lowest number of taxa appeared at the edges of openings. In the light of these investigations, it may be assumed that heterogenous microsite conditions in openings enable the recruitment of taxa with various germination requirements and contribute to the maintenance of species diversity.

33-45