Restoration of alcalic and steppe grasslands in arable fileds with low diversity seed mixtures – a case study at the Hortobágy National Park (Egyek-Pusztakócs)

Abstract

In the last three years (2005–2007) we restored 496 ha grassland on former arable fields. We aimed at to create a dense perennial cover by sowing seed mixtures of dominant alkali and loess grasses (Festuca pseudovina, F. rupicola, Poa angustifolia, Bromus inermis). In October every year after the preparation of seed beds, we sowed the seed mixtures in density of 25kg/ha in 2005 and 2006, and 18kg/ha in 2007. We managed the sown fields from the first year onwards with mowing (once or twice a year) and moderate grazing (sheep and/or cattle) to prevent the regeneration of weed species. In the first spring after sowing the early vegetation were dominated by herbaceous weeds (Tripleurospermum inodorum, Bromus arvensis, Thlaspi arvense, Capsella bursa-pastoris, Descurainia sophia, Cirsium arvense, Fumaria officinalis). The cover of the weeds protected the seedlings of sown grasses from the direct sunlight and preserved suitable moisture conditions for development. In the second year we detected an increase of perennial cover and a decrease of species richness and cover of early weeds compared to the first year. We also detected immigration of perennial herbaceous species in the restoration area (Silene viscosa, Dianthus giganteiformis ssp. pontederae, Koeleria cristata, Salvia nemorosa, Salvia austriaca, Trifolium angulatum, T. striatum, Artemisia santonicum, Scorzonera cana) dispersed mainly by anemochory or by grazing animals. Our results suggest that the sowing of competitive grass seeds is an effective tool to restore alkali and loess grasslands. The spontaneous immigration of typical loess and alkali herbaceous perennial species is slow; further management practices are needed to enhance the diversity and species richness of the newly restored grasslands (seeding, hay transport, grazing).