Replenishment of the endangered Echinospartum algibicum (Genisteae, Fabaceae) from the soil seed bank Original Research Article

Echinospartum algibicum is a very recently described species. It is currently only known from one population in southern Spain and is in serious danger of extinction as only three out of 92 living plants are able to flower and set fruit because of grazing. The aim of the work presented in this paper was to study the seed density and distribution in the permanent soil seed bank, and to assess the possibility of replenishing this species from the seed bank. A total of 101·25 litres of soil from 90 soil cores at three different depth levels (0–5, 5–10 and 10–15 cm) in three different plots was sampled within the population. Each recovered buried seed was individually weighed and tested for viability, together with a sample of 30 freshly collected seeds; seedling development was also monitored. One hundred and thirteen seeds (167 seeds m−2) were recovered and the number of seeds was not statistically different among plots. Mean seed mass of buried seeds was significantly different between plots and also compared to fresh seeds. Scarification significantly increased seedling emergence, after a 20-day test. Germination differed among plots but not among the soil layers at different depths. Viable seeds had greater mean seed mass than non-viable seeds, but there did not seem to be a critical seed mass for germination. Most seedlings died before 20 weeks; therefore, despite the high germination percentages observed in this study both in buried and fresh seeds, seedling survival was extremely low. In-situ conservation measures and studies are suggested.