Recovery of inland sand dune grasslands following the removal of alien pine plantation

Exotic pine species are used for afforestation worldwide resulting in negative consequences for biodiversity. Changing economic or conservation priorities are increasingly leading to the removal of these plantations, but the ability of these stands to recover into natural communities varies across ecosystems. In this study, we assessed the recovery of open and closed grasslands over five years following the removal of alien pine plantations through burning at an inland sand dune system in Hungary. We compared soil characteristics, plant species richness, cover, and community composition of recovering and control grasslands at two elevation zones. We found minor differences in soil characteristics between recovering and control grasslands suggesting that abiotic conditions were unlikely to limit vegetation recovery. Plot-level species richness and total cover did not differ between control and recovering plots. Open sand grassland species, which dominated high-zone control grasslands, recovered in both zones in terms of species richness, but not in cover. Closed grassland species, which dominated low-zone control grasslands, did not recover except for a native weed, Calamagrostis epigeios, most likely primarily due to the decline of the water table in the region. The differential recovery of the two grassland types and the dominance of weedy perennials led to biotic homogenization. We conclude that conservation planning should (1) view these recovering stands as valuable secondary grasslands that develop towards open grasslands, and (2) focus on the preservation of primary closed grasslands in order to maintain the landscape-scale mosaic of open and closed grasslands in the region.