A Guided Tour of the Soil Seed Banks

The soil seed bank could be viewed as an optimization of the chances of the plants to meet favourable conditions in time and in space. Owing to the large amount of publications and the field complexity, available reviews do not cover the entire field. My objective was to produce a synthesis. Determination of the soil seed bank needs careful planning of sampling because of variations with soil depth and clumped distributions. Sample composition is determined from plantlets coming from germinated seeds after exposure to appropriate conditions or directly from seeds after their separation from soil particles. Seed longevity varies from months to decades and depends on desiccation resistance, defences against predators and germination control, notably dormancy. Dormancy characterization and alleviation factors allow to understand species strategies in ecosystems. In agricultural soils, weeds challenge future cultures. Research objectives are often to exhaust their seed banks before crop emergence by reducing seed production, inactivating germination, removing weeds before seed maturation, and controlling the harvest. In natural ecosystems, there are considerable differences in dormancy according to ecological conditions but climax species tend to produce shorter-lived seeds compared to pioneered ones. The soil seed bank may help in restoring degraded vegetation but similarity with the aboveground vegetation is low. Disturbances may increase or decrease the soil seed bank diversity. Restoration may often rely on natural recruitment from undisturbed areas or on artificial translocation. I emphasize the need to integrate soil seed bank knowledge in dynamic vegetation modelling which generally lack most of the soil seed bank features while future distribution of plant species is one of the main question in this climate change era.