Edaphic factors influence the longevity of seeds in the soil

A thorough understanding of the rate of depletion of ungerminated seeds in soil is necessary to understand and model the population dynamics of many plant species. To assess how edaphic conditions influence seed survival over time a long-term field study was set up. Mesh bags of seeds of 12 species were buried under 12 contrasting semi-natural and grassland habitats and retrieved at intervals over 10 years. Seed survival and viability were assessed through germination trials and chemical staining. There were clear differences in the rate of depletion of ungerminated seed between species and also differences in the variability of this measure between habitats. Seed survival was longer in soils with a higher pH, lower moisture content and lower soil C:N. Soil characteristics need to be taken into account within studies of plant populations that depend on regeneration from seed, particularly for species where seed survival is sensitive to edaphic conditions. Ignoring this influence of the dynamics of seeds under different soil conditions may have a serious impact on the success of population modelling.