Successfully Recovered Grassland: A Promising Example from Romanian Old-Fields

In this study, I analyzed the natural recovery of grasslands on abandoned agricultural fields in the Transylvanian Lowland (Câmpia Transilvaniei), Romania. I examined fields that were abandoned 1–40 years ago and considered how successful they have been in recovering spontaneously as compared to reference grassland, especially in relation to species composition and dominance structure. Diverse, nondegraded seminatural grasslands from the surroundings were chosen as targets for the recovery. Five such grasslands were analyzed in order to have multiple references that accounted for site heterogeneity and different land use history. This study found that the number of natural and seminatural habitat species increased, whereas the number of weeds and aliens decreased with age. Old-fields had become very similar in species composition and dominance structure to reference grasslands over a 14- to 20-year time interval, with the only failure being the unsuccessful or slow colonization of a few grassland species. Because spontaneous succession is efficient, human interventions are not needed to restore target communities on the old-fields. Propagule pressure expressed by the area of potential seed source in a 500-m-radius buffer was found to have a strong influence on recovery success of old-fields. The success of grassland species in colonizing postagricultural fields was not affected by their dispersal mode but by their frequency in the landscape, this being another evidence for the importance of propagule availability in the course of recovery. In order to maintain the potential for recovery of this landscape, we need to protect those close to natural habitats that contain a high amount of native flora.