Dynamics in vegetation and seed bank composition highlight the importance of post-restoration management in sown grasslands

Sowing grasses supports the rapid development of a closed perennial vegetation, which makes the method universally suitable for fast and effective landscape-scale restoration of grasslands. However, to increase their diversity and to create a natural-like species-rich grassland is a challenging task. Understanding the role of seed bank compositional changes and vegetation dynamics can help to design management regimes that support the establishment of target species and suppress unwanted weeds. Our aim was to reveal the effect of post-restoration management on the vegetation and seed bank dynamics in grasslands restored in one of the largest European landscape-scale restoration projects. Eight years after restoration, we sampled the vegetation and the seed bank in 96 quadrats located in 12 restored grasslands in the Great Hungarian Plain. In each grassland stand, we studied and compared a mown (mown from Year 1 to Year 8) and an abandoned plot (mown from Year 1 to Year 3 then abandoned from Year 4 to Year 8). Mown and abandoned plots showed divergent vegetation and seed bank development. Abandonment led to the decline of sown grasses and higher cover of weeds, especially in the alkaline grasslands. Our study underlined that the developing seed bank had a limited contribution to the maintenance of biodiversity in both grassland types. We found that 5 years of abandonment had a larger effect on the seed bank than on the vegetation. We stress that long-term management is crucial for controlling the emergence of the weeds from their dense seed bank in restored grasslands.

Automated summary

Planting grasses can help establish closed perennial vegetation quickly, but creating diverse and natural-like grasslands is challenging. Understanding seed bank changes and vegetation dynamics is crucial for effective grassland restoration management. Long-term management is necessary for controlling weed emergence from dense seed banks in restored grasslands.