Soil seed banks and dormancy cycling have been well studied in annuals, but less is known about woody plants. Cao et al. investigate the cold desert shrub Kalidium gracile (Amaranthaceae) and find that it has three life history traits that help ensure persistence at a site: a polycarpic perennial life cycle, a persistent seed bank and dormancy cycling. Buried seeds exhibit an annual non-dormancy/conditional dormancy cycle, and germination varies in sensitivity to salinity during the cycle. Dormancy cycling is co-ordinated with seasonal environmental conditions in such a way that the seeds germinate in summer, when there is sufficient precipitation for seedling establishment.
Seed persistence in the soil under field conditions is issue for the maintenance of local plant populations and the restoration of plant communities. Saatkamp et al. compare seed survival in a burial experiment with data on various germination traits for a range of Mediterranean annual plants. Germination rate, light requirement for germination and germination in response to diurnally fluctating temperatures are found to be related to seed survival; however, survival differs according to season and this interacts with germination traits.