Restoration of semi-natural grasslands boosts biodiversity and re-creates hotspots for ecosystem services

Semi-natural grasslands and their diverse biota are threatened by changes in land-use like afforestation, abandonment of traditional practices, urban development or conversion into intensive agricultural land. Extensive loss and fragmentation of semi-natural grasslands consequently affects ecosystem functioning inherit to open landscapes and the sustainable provision of ecosystem services. Ecological restoration of grasslands has potential to halt further decline and hopefully reverse some of the damage done to the grasslands and vital ecosystem services they provide. By assessing grasslands before and after the restoration, we evaluated how restoring overgrown and forested semi-natural grasslands to open grasslands impacts nine ecosystem services: habitat maintenance, soil condition maintenance, soil carbon storage, pollination, pest regulation, provision of wild food and medicinal herbs, forage production, wood production and recreation. We also analyzed the relationship between ecosystem multifunctionality and species richness of multiple organism groups. We found that already few years after restoration, restored grasslands exhibited rapidly increasing biodiversity and ecosystem service provision. Similarly, the overall ecosystem multifunctionality increased significantly after restoration in previously overgrown and afforested grasslands. However, while a robust and strong positive relationship between multitrophic diversity and ecosystem multifunctionality existed before restoration, this relationship was somewhat weakened after restoration. We propose two potential explanations: first, the previously distinct condition classes became more similar, starting to resemble open grassland habitats in their species richness and composition. Second, the relationship may have been weakened by the temporarily disrupted and transitional nature of the ecosystem post-restoration, due to varying recovery rates among different species groups and ecosystem services. Notably, soil-related services (carbon storage and soil maintenance) take longer to respond to restoration, compared to other services. In addition, we detected significant negative impact of prolonged drought on pest regulation and forage production service in both restored and unrestored areas. Semi-natural grasslands are both biodiversity and ecosystem service "hotspots" in European landscapes and restoring these habitats significantly increases the provision potential of important ecosystem services. However, restoration planning must consider landscape history, regional characteristics and the importance of long-term monitoring for getting the most accurate results.