Semi-natural grasslands harbour many of Europe's species of conservation interest. Although larger grasslands are the focus of most conservation activity, many grassland fragments are scattered across landscapes –in small patches or along linear elements– which can form Grassland Green Infrastructure (GGI). GGI has the potential to enhance landscape diversity by creating functioning metacommunities comprising of large semi-natural grasslands and these surrounding fragments. While often highlighted in conservation policy, little is known about the biodiversity supported by green infrastructure itself and thus its conservation potential.

To address this issue, we contrasted plant communities in 36 ‘core’ grassland sites across three European countries with communities in the surrounding GGI. We related compositional differences to amount and type of GGI habitat (patches or linear), and the distances for seed dispersal by livestock from core sites. We found substantial differences between the GGI and the core sites, with a mean 54% species turn-over. These differences indicated filtering of stress tolerant species characteristic of low nutrient conditions, and semi-natural grassland specialists. Species with poorer dispersal abilities declined strongly with increasing distances from the core sites. The many additional species in the GGI, not found in the core sites, were predominantly those with a competitive strategy and high seed dispersal ability.

We conclude that the biodiversity-supporting role of GGI across Europe is severely constrained by eutrophication, dispersal limitation and external propagule pressure. Actions to improve the quality of GGI might include enhancing dispersal by livestock combined with more type-diversification and less intensively used grassland habitats., This research was funded through the 2015-2016 BiodivERsA COFUND call for research proposals, with the national funders FORMAS (2016-01948), the Swedish Environmental Protection Agency (Naturvårdsverket), the Belgian Science Policy Office (BelSPo, BR/175/A1/FUNgreen), the Germany Federal Ministry of Education and Research (Bundesministerium fuer Bildung und Forschung, FKZ: 01LC1619A) and the Spanish Ministry of Science, Innovation and Universities (Ministerio de Ciencia, Innovación y Universidades, PCIN-2016-077). JMB was funded under UKCEH National Capability project 06895., Peer reviewed

Agricultural intensification, afforestation and land abandonment are major drivers of biodiversity loss in semi-natural grasslands across Europe. Reversing these losses requires the reinstatement of plant–animal interactions such as pollination. Here we assessed the differences in species composition and patterns of plant-pollinator interactions in ancient and restored grasslands and how these patterns are influenced by landscape connectivity, across three European regions (Belgium, Germany and Sweden). We evaluated the differences in pollinator community assemblage, abundance and interaction network structure between 24 ancient and restored grasslands. We then assessed the effect of surrounding landscape functional connectivity (i.e. green infrastructure, GI) on these variables and tested possible consequences on the reproduction of two model plants, Lotus corniculatus and Salvia pratensis. Neither pollinator richness nor species composition differed between ancient and restored grasslands. A high turnover of interactions across grasslands was detected but was mainly due to replacement of pollinator and plant species. The impact of grassland restoration was consistent across various pollinator functional groups, whereas the surrounding GI had differential effects. Notably, bees, butterflies, beetles, and dipterans (excluding hoverflies) exhibited the most significant responses to GI variations. Interestingly, networks in restored grasslands were more specialised (i.e. less functionally redundant) than in ancient ones and also showed a higher number of insect visits to habitat-generalist plant species. Landscape connectivity had a similar effect, with habitat-specialist plant species receiving fewer visits at higher GI values. Fruit set in S. pratensis and L. corniculatus was unaffected by grassland type or GI. However, the fruit set in the specialist S. pratensis increased with the number of pollinator visits, indicating a positive correlation between pollinator activity and reproductive success in this particular species. Synthesis and applications. Our findings provide evidence of the necessity to enhance ecosystem functions while avoiding biotic homogenisation. Restoration programs should aim at increasing landscape connectivity which influences plant communities, pollinator assemblages and their interaction patterns. To avoid generalist species taking over from specialists in restored grasslands, we suggest reinforcing the presence of specialist species in the latter, for instance by means of introductions, as well as increasing the connectivity to source populations., This research was funded through the 2015–2016 BiodivERsA COFUND call for research proposals, with the national funders FORMAS (2016–01948), the Swedish Environmental Protection Agency (Naturvårdsverket), the Belgian Science Policy Office (BelSPo, BELPSPO/BR/175/A1/FUNgreen), the Germany Federal Ministry of Education and Research (Bundesministerium fuer Bildung und Forschung, FKZ: 01LC1619A) and the Spanish Ministry of Science, Innovation and Universities (Ministerio de Ciencia, Innovación y Universidades, PCIN-2016-077). JMB was funded under UKCEH National Capability project 06895; DAPH was contracted from Stockholm University as external scientist (contract reference 463). CLR was supported by a Juan de la Cierva Formación postdoctoral fellowship (Ministerio de Economía, Industria y Competitividad: FJCI-2015-24712)., Peer reviewed

[Methods] We sampled plant-pollinator interactions five times at each of the 24 focal grasslands throughout the main flowering periods of 2018. We shifted geographically with the flowering period (May 3rd-June 6th-in Germany, June 14th-July 8th in Belgium and July 10th-August 9th in Sweden), from 9 a.m. to 6 p.m. on sunny days with low wind, and above 15ºC. We gathered flower visitation data along three parallel linear transects (80m long and 3m wide) over 45 min (15 min per transect). We recorded the identity and number of insect contacts to flowers, considering only those (i.e. potential pollination events) when an insect clearly touched the flower reproductive organs., Agricultural intensification, afforestation and land abandonment are major drivers of biodiversity loss in semi-natural grasslands across Europe. Reversing these losses requires the reinstatement of plant-animal interactions such as pollination. Here we assessed the differences in species composition and patterns of plant-pollinator interactions in ancient and restored grasslands and how these patterns are influenced by landscape connectivity, across three European regions (Belgium, Germany and Sweden). We evaluated the differences in pollinator community assemblage, abundance, and interaction network structure between 24 ancient and restored grasslands. We then assessed the effect of surrounding landscape functional connectivity (i.e. green infrastructure, GI) on these variables and tested possible consequences on the reproduction of two model plants, Lotus corniculatus and Salvia pratensis. Neither pollinator richness nor species composition differed between ancient and restored grasslands. A high turnover of interactions across grasslands was detected but was mainly due to replacement of pollinator and plant species. The impact of grassland restoration was consistent across various pollinator functional groups, whereas the surrounding GI had differential effects. Notably, bees, butterflies, beetles, and dipterans (excluding hoverflies) exhibited the most significant responses to GI variations. Interestingly, networks in restored grasslands were more specialised (i.e. less functionally redundant) than in ancient ones and also showed a higher number of insect visits to habitat-generalist plant species. Landscape connectivity had a similar effect, with habitat-specialist plant species receiving fewer visits at higher GI values. Fruit set in S. pratensis and L. corniculatus was unaffected by grassland type or GI. However, the fruit set in the specialist S. pratensis increased with the number of pollinator visits, indicating a positive correlation between pollinator activity and reproductive success in this particular species. Synthesis and applications. Our findings provide evidence of the necessity to enhance ecosystem functions while avoiding biotic homogenization. Restoration programs should aim at increasing landscape connectivity which influences plant communities, pollinator assemblages, and their interaction patterns. To avoid generalist species taking over from specialists in restored grasslands, we suggest reinforcing the presence of specialist species in the latter, for instance by means of introductions, as well as increasing the connectivity to source populations., Swedish Environmental Protection Agency: 2016–01948, Belgian Federal Science Policy Office: BELPSPO/BR/ 175/A1/FUNgreen, Federal Ministry of Education and Research: FKZ: 01LC1619A, Ministerio de Ciencia e Innovación: PCIN- 2016-077., Peer reviewed