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

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 on the ground was highly influenced by the presence or absence of adult plants and by the indehiscent character of the fruit.Results showed that most seeds were present in the surface layer, inside fruit and close to the mother plant.Seed longevity was low in general, but higher for seeds protected by fruit than for single ones after two years of burial.We discuss our results in relation with other patterns of seed dispersal or viability in arid environments, that are generally characterized by high spatial and temporal variability with a short-range dispersal.We concluded that this species is able to form a short-term persistent soil seed bank strongly influenced by environmental factors and population fluctuations.Based on these results, natural regeneration of patches locally extinct some years ago is unlikely from the soil seed bank and recovery should be attempted by sowing seeds or planting new specimens.