Regeneration of sandy old-fields in the forest steppe region of Hungary

Abandoned agricultural fields are potential sites for the regeneration of natural vegetation, and land abandonment is a widespread phenomenon in the developed world. We studied the vegetation of 161 old-fields in the Kiskunsag, central Hungary. Old-fields were categorized into three age groups based on historical aerial photographs: fields abandoned 1-7, 820, and 21-57 years ago. Old-field vegetation was compared to potential target communities (open and closed grassland and forest) based on the richness and cover of predefined species groups (all species, neophytes, characteristic species of natural habitats). In general, the medium-and old-aged old-fields only slightly differed from each other, and were more similar to open natural grasslands than to closed ones, although they occupied environments that were intermediate between open and closed grasslands. Forest species establishment was limited in the old-fields; therefore, forest regeneration seems to be unlikely on old-fields at a decadal time scale. The dominance of alien species only slightly declined with old-field age and was much higher than in natural grasslands. The finding that open grassland communities recovered on these old-field sites, but were accompanied by stable alien components, suggests that these communities could be regarded as a new combination of species, or novel communities, with a considerably high conservation value.