Forests of Děvín Nature Protected Area belong to the most remarkable remnants of mesophilous pannonian forest communities in the Czech Republic. Since the medieval they were intensively managed, with a clear-cut period of about 10 years. In 1946 the Děvín Nature Protected Area was established and forests remained unmanaged until today; game preserve was however cancelled only in 1996. This resulted in a succession towards 50–90 years old forests by now, while the undergrowth vegetation was under rather intensive influence of ungulates.
In the 1950s and 1960s the forests were described within a forestry research. Well-localised records from about 200 vegetation plots and 35 described and analysed soil profiles were repeated using original methodology in 2002–2003.
Two main processes were observed in vegetation. 1. Canopy became closer; forests are more shady and colder; herb and shrub layers became notably species-poorer. The total diversity is however probably not much changed yet. Light-demanding species disappeared, graminoids in particular. 2. Overall eutrophization due to forest maturing, influence of ungulates, and probably also airborne nitrogen deposits. Notably, nitrophilous Impatiens parviflora and Geum urbanum invaded the forests. Nutrient-demanding tree species (as Fraxinus excelsior, Tilia platyphyllos and Acer app.) increased. Soils reflect the gradual forest succession. Illimerisation seems to be the main process, which is a result of transition from open canopy to the closed forest.
To maintain the biodiversity of forests in Děvín, a partial application of traditional management is recommended. Otherwise, forest ecosystems will become homogeneous, relatively species-poor communities, while some rare and species-rich forest types (thermophilous oak forests) will probably decrease notably.