Alien and native woody plants in scattered vegetation in agricultural landscape

The woody plant species composition has been evaluated in three cadastral territories of southwestern Slovakia, together in 77 habitats of non-forest woody vegetation (NFWV). A total of 43 tree species have been identified; 8 of them were alien and 5 species were cultural fruit trees. In total 20 shrub species were identified, out of which 3 were alien. Three woody species are classified as invasive according to the law in Slovakia: Acer negundo L., Ailanthus altissima (Mill.) Swingle, and Lycium barbarum L. They occurred only in 2, maximum in 4 of the evaluated habitats. The most occurring alien tree species Robinia pseudoacacia L. was generally identified in 58 habitats and in 48 habitats, with an incidence over 40% and dominance index of 70.6. The second most occurring alien tree Populus × canadensis had a dominance index of 8.3. The dominant native trees in NFWV were Acer campestre L., Fraxinus excelsior L., Quercus robur L., Salix fragilis L. with the dominance index of 1–5 only.