Authors: Török, Péter; Teleki, Balázs;Sonkoly, Judit;Erdős, László;Prommer, Mátyás;Tóthmérész, Béla;

We aimed to study the effect of native shrub encroachment on plant biodiversity in grassland fragments by analysing the vegetation composition of grasslands subjected to increasing levels of encroachment. Both ancient and spontaneously recovered grasslands were studied. We set the following research hypotheses: (i) increasing levels of encroachment decreases total diversity and the species richness of dry-grassland species; and (ii) the effect of woody cover on grassland biodiversity differs between ancient and restored grasslands. Altogether in 63 grassland fragments the percentage cover of trees, shrubs and herbaceous vegetation were recorded. Shrub encroachment affected the total richness of the herb layer and the species richness of dry-grassland species. For most of the studied variables, lowest values were found for the highest encroachment groups. Species richness of the herb layer and that of dry-grassland species were lower in restored grasslands. In recovered grasslands, Shannon diversity and species evenness were lower, while Berger-Parker dominance was higher than in ancient grasslands. Species composition and richness displayed a relatively high resistance to moderate shrub encroachment. Our results suggest that moderately encroached loess grasslands can be easily restored by the suppression of woody species, as their species pool still contains many dry-grassland species targeted for restoration.