Could recently locally extinct population patches of Astragalus nitidiflorus regenerate from the soil seed bank?

• Astragalus nitidiflorus is an endemism classified as critically endangered.
• The seed bank was poor and very sensitive to changes in population size.
• Indehiscent fruit determines seed distribution in the soil around mother plants.
• A. nitidiflorus is able to form a short-term persistent soil seed bank.
• Natural regeneration is not expected for patches where the species disappeared few years ago.

Persistence, distribution, and dynamics of Astragalus nitidiflorus soil seed bank, a critically endangered species of southern Spain, were studied during four consecutive years to determine their importance to regenerate locally extinct patches of the only known A. nitidiflorus population worldwide. The spatial distribution of seeds in the soil was highly influenced by the presence/absence of adult plants and by the indehiscent trait of the fruit. Results showed that most seeds were present on the soil surface, inside the fruit and close to the mother plant. Seed longevity was low, but higher for seeds protected by fruit than for single ones after two years buried in the soil. This species is able to form a short-term persistent soil seed bank that is strongly influenced by environmental factors and population fluctuations. Based on these results, natural regeneration of local patches where plants of A. nitidiflorus are no longer present is unlikely from the soil seed bank and population recovery should be attempted by sowing seeds or planting new specimens.