Soil seed banks are reserves of viable seeds present on the soil surface and in the soil. The seed bank consists of new seeds recently shed by nearby plants as well as older seeds that have persisted in the soil for several years. The seed bank is an indicator of past and present plant populations. There are usually enormous numbers of viable seeds in the soil. Although a great number of the buried seeds lose their ability to germinate within a few years, seeds of some species can remain viable for decades. It has been estimated that only 1-9% of the viable seeds produced in a given year develop into seedlings; the rest remain viable and will germinate in subsequent years depending on the depth of their burial and local conditions. Some data have suggested that it is possible for certain seeds to remain viable for over 100 years.It has been reported that the majority (approximately 95%) of the seeds entering the seed bank are from annual plants, only about 4% come from perennials. Seed bank input, or seed rain, is the number of seeds produced by flowering plants at the site. Some species are capable of producing thousands of seeds.
Studies so far have shown that the majority of the seeds remain at or near the soil surface in undisturbed soils. Seeds on, or close to, the soil surface are most susceptible to mortality from predation (small mammals, birds, foraging insects) and from infection by fungi in moist conditions. Seeds will tend to germinate under favorable environmental conditions, thus depleting the seed bank.
A study of seed banks in the Grand Canyon showed a high variability in the number of seeds per square meter of soil and that 25% of the species were exotic plants.
Tillage, Soil Type and Weed Seed Bank Dynamics
The Soil Seed Bank
Weed Seed Banks...