Effects of landscape composition, species pool and time on grassland specialists in restored semi-natural grasslands

- We analysed temporal and landscape effects on grassland specialist plants in restored semi-natural grasslands.
- Plant richness was positively affected by a large specialist species pool.
- Plant frequency increased with the proportion of semi-natural and remnant grasslands in the landscape.
- Plant richness increased with time since restoration.
- For long-term restoration success both temporal and spatial processes should be considered.

Habitat restoration is an important complement to protecting habitat for the conservation of biodiversity. Semi-natural grasslands are target habitats for ecological restoration in temperate Europe. Restoration of abandoned semi-natural grasslands often relies on spontaneous colonisation of plant species from the soil seed bank or the surrounding landscape. Although many studies show that the regional species pool is important for upholding local diversity, its effect on restoration outcome in semi-natural grasslands is poorly known. In this multi-landscape study, we examined grassland specialist species occurring in restored grasslands and the effect of specialist species pool, landscape composition and local temporal factors. We found that specialist richness and frequency was positively affected by specialist richness and frequency in the surrounding landscape. Specialist richness in the restored grasslands also increased with time since restoration. Moreover, specialist frequency in the restored grassland increased with the proportion of semi-natural and remnant grassland habitats in the landscape. We also found a positive relationship between the proportion of species occurring in both the restored grassland and its surrounding landscape and time since restoration, in landscapes with high proportions of semi-natural grasslands. This suggests that both temporal factors, as well as the landscape composition and species pool, affect plant recolonisation in restored semi-natural grasslands.