Seed regeneration in Mediterranean temporary ponds: germination ecophysiology and vegetation processes

Mediterranean temporary ponds (MTPs) are very specialised and threatened habitats found in Mediterranean-like bioclimates worldwide. MTPs have received considerable attention over the past years because of the multiple ecological roles they play in the landscape. Nevertheless, seed germination, dormancy, and desiccation tolerance of species living in MTPs are poorly investigated. Here, we reviewed these topics and found that seed germination data exist for only 48 species. While dormancy differs among the species, germination mostly depends on cool temperatures (<15°C) which are associated with the main rainfall season and on the light triggering germination in seeds located close to the soil surface and resulting in the persistence of buried seeds until disturbances occur. Most species seem amenable to seed banking as a means of ex situ conservation but a worldwide comparative study is required to better understand seed lifespan in MTPs. In general, these species exhibit a Mediterranean germination syndrome and plastic germination response that is typical of neither truly aquatic nor wetland plants. The importance of conducting ecologically meaningful germination studies, including germination experiments conducted in the field has been highlighted to gain further insights into the dynamic processes in the vegetation and to test for convergent evolution.