Global and regional conservation status of vascular wetland plants in Mediterranean islands: a collaborative network to improve knowledge and awareness

Mediterranean wetlands are highly sensitive ecosystems, particularly vulnerable to human pressure and shifts in precipitation and temperature regimes. Wetland plants can be particularly threatened in Mediterranean insular contexts, where such habitats are naturally smaller and more fragmented than in their continental counterparts. This study investigated 275 species of vascular wetland plants that were considered to be at least regionally threatened across 2217 islands and islets in the Mediterranean. We provided both global and local IUCN conservation assessments (summarized in a 'conservation concern' index) and 'assessment completion' (i.e. knowledge level) for each taxon as well as a geographic distribution among islands, wetland types, and life forms. Most of wetland plants were threatened at the regional level, although assessment completion was generally low, except for endemics. Inland and endemic wetland plants were more threatened than the rest. A phylogenetic signal was detected, highlighting that Orchidaceae and Apiaceae were of particularly high conservation concern, while other families, especially Amaranthaceae, exhibited low levels of assessment completion. No geographical patterns were found in terms of conservation concern and assessment completion. Our findings provide critical insights into biodiversity patterns, identify conservation gaps and priorities and contribute to the development of targeted strategies for the protection of wetland plants, which are crucial indicators of the entire natural capital of Mediterranean island ecosystems.