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Description  

• Grasslands are areas of land predominantly covered by communities of grass-like plants and forbs and may include sparsely occurring trees and shrubs. In the Eurostat classification, percentages of area covered by such canopies are limited to less than 10 % in the case of trees and to less than 20 % in the case of shrubs (i.e., low woody plants capable of reaching heights of up to 5 metresmetres [2]) or shrubs and trees togethertogether [3]. However, in the scientific literature reviewed here, grasslands are usually more broadly defined and might not fully meet such canopy limits. 
• This review includes a wide variety of grassland types: savannah, grassy deserts, seasonally flooded grasslands, prairies, meadows, pastures, rangelands, salt-marshes, bioenergy perennial grasslands, calcareous grasslands and wooded grasslands. Grasslands differ in terms of: 

• management intensity: natural, semi-natural, improved and intensively managed, 
• management history: permanent and temporary, 
• successional stage: old successional and secondary grasslands, 
• biomes and climates: semi-arid, temperate, tropical, Mediterranean, tundra, alpine, subalpine, artic and subartic. 

• Fodder crops are not included as grasslands. 
• Grassland conservation refers to the preservation (i.e., no transformation to other land uses) of old successional natural grasslands. Old successional natural grasslands are grasses and forbs communities with no major human-induced structural or functional alterations so that their current management closely resembles historical, endogenous disturbance regimes (e.g., grazing intensity and fire frequency) [4]. In the scientific literature, these ecosystems are also referred as old-growth, ancient, remnant or native grasslands. 
• Grassland restoration includes active and passive restoration methods usually aiming at enhancing plant community diversity, what is then expected to have cascading positive effects in higher trophic levels5. This review includes several restoration methods: sowing of seed mixtures, addition of soil and hay, reintroduction of grazing and burning as active restoration methods, and abandonment of agricultural use as passive restoration method. In this review, we only consider the restoration of former grassland areas degraded by agricultural use (i.e., degradation due to mining or other land uses are excluded). We define secondary grasslands as the herbaceous communities that assemble after destruction (here, by agricultural use) of old successional natural grasslandsgrasslands [4] where the restoration efforts are conducted. 

Key descriptors  

• For the exploration of grassland conservation, this review includes the spatial comparison between preserved old successional natural grasslands (intervention) and nearby secondary grasslands, either restored or degraded, as control. 
• For the exploration of grassland restoration, this review includes spatial and temporal comparisons between restored grasslands (intervention) and croplands or secondary grasslands after crop abandonment as controls. Spatial comparisons are those conducted simultaneously between restored grasslands and nearby croplands (or secondary grasslands after crop abandonment). Temporal comparisons are those conducted in the same site before (when land use was cropland or abandoned cropland) and after restoration into grassland. 
• In this review, grassland restoration includes restoration into different types of grasslands, including perennial bioenergy grasslands. 
• This review does not include grazing or other management practices (i.e, soil amendment and fertilisation, mowing, increasing grass species richness) conducted in grasslands, which are assessed in separate sets of fiches.