A Guided Tour of the Soil Seed Banks

Abstract

The soil seed bank could be viewed as an optimisation of the chances of plants to meet favourable conditions in time and space. Owing to the large number of publications and the field’s 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 in 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 characterisation 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, climax species tend to produce shorter-lived seeds compared to pioneered ones. The soil seed bank may help in restoring degraded vegetation but the 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 emphasise the need to integrate soil seed bank knowledge into dynamic vegetation models, which generally lacks most of the soil seed bank features, while the future distribution of the plant species is one of the main questions in this climate change era.