A seed bank is the reservoir of viable seeds present in a plant community. Seed banks are evaluated by a variety of methods. For some species, it is possible to make careful, direct counts of viable seeds. In most cases, however, the surface substrate of the ecosystem must be collected and seeds encouraged to germinate by exposure to light, moisture, and warmth. The germinating seedlings are then counted and, where possible, identified to species.

In most cases, the majority of seeds are found in surface layers. For example, the organic-rich forest floor contains almost all of the forest's seed bank, with much smaller numbers of seeds present in the mineral soil.

The seeds of some plant species can be remarkably long-lived, extending the life of the seed bank. For example, in northeastern North America, the seeds of pin cherry (Prunus pensylvanica) and red raspberry (Rubus idaeus...