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Despite their importance for biodiversity and ecosystem services, wetlands are among the most threatened ecosystems globally. The conservation of many migratory waterbirds depends on the conservation of a network of key sites along their flyways. However, the suitability of these sites is changing under climate change, and it is important that management of individual sites in the network adapts to these changes. Using bioclimatic models that also account for changes in inundation, we found that projected climate change will reduce habitat suitability for waterbirds at 57.5% of existing Critical Sites within Africa-Eurasia, varying from 20.1% in Eastern Europe to 87.0% in Africa. African and Middle East sites are particularly threatened, comprising 71 of the 100 most vulnerable sites. By highlighting priority sites for conservation and classifying Critical Sites into Climate Change Adaptation Strategy (CCAS) classes, our results can be used to support the climate change adaptation of both individual sites and the entire site network.

Summary 1 We need to understand how threatened plant species respond to natural or management-induced habitat changes to conserve them successfully. Because long-term demographic studies are not feasible for large numbers of species, there is a clear need for simple short-term methods to assess demographic responses. 2 The population structure of 23 populations of the endangered perennial Salviapratensis was studied in relation to the vegetation and management of dry floodplain grasslands along Dutch rivers. The aims of the study were to (i) evaluate the suitability of single censuses of population stage structures as a tool for quick assessments of the viability of plant populations; (ii) test whether viable populations of S. pratensis indicate sites of higher conservation value; (iii) obtain information on the viability of the remaining populations; and (iv) provide advice for optimal habitat management. 3 Using cluster analysis, we distinguished three different types of populations: (i) ‘dynamic’ populations, characterized by a large proportion of young individuals (seedlings, juveniles and immatures); (ii) ‘normal’ populations, with a relatively higher proportion of adults but still a considerable number of young individuals; and (iii) ‘regressive’ populations, in which adult stages, especially large flowering individuals, dominated and rejuvenation hardly occurred. The three population types differed with respect to population size and total plant density, which were highest in dynamic, intermediate in normal and lowest in regressive populations. 4 Both the structure and composition of the surrounding vegetation were associated with the type of population found. The percentage of bare soil surface (indicating an open vegetation structure) was positively related to recruitment of S. pratensis. The dynamic populations occurred in a species-rich vegetation, comprising species of nutrient-poor soils and characteristic of floodplain grasslands. The regressive populations occurred more often in species-poor vegetation, comprising mainly species of nutrient-rich conditions. 5 Salvia population structure was correlated with management. We observed that those populations with a late mowing regime had higher proportions of young stages and larger population sizes. Although we expected that recently established populations on the young river dunes formed during ecological restoration projects would be dynamic, most sampled plots were of the regressive type, which suggests that either site conditions were not yet optimal or Allee effects limited further expansion of the small founder populations. 6 We conclude that conservation of the remaining populations of S. pratensis in Dutch dry floodplain grasslands will be best achieved by late mowing with hay removal.