Spontaneous dynamics of unmanaged floodplain oak and submontaneous Illyrian beech forests were compared in the Pannonian ecoregion (southern Hungary), with special respect to changes of abundance of species in the ground layer. Due to gap forming, light availability, estimated by Ellenberg indicator values, improved significantly in oak stands, in a smaller extent in beech stands. Oak regenerated very poorly in the unmanaged stands, but the diversity of tree seedlings increased. On the other hand, in beech forests the diversity of tree regeneration decreased notably, due to dominance of beech seedlings. No light-demanding specialist species appeared. Changes in share of shade-tolerant specialists were controversial. Serious conservational concerns regarding the spread of weeds and invasive species were not confirmed, as their share did not exceed 1.5% in the floodplain oak stands either. Our results draw attention to that experiences on close-to-nature silviculture gained in beech forests should be applied precautiously in other forest with quite different natural dynamics.
