What is a seed bank? A seed bank is a repository of living seeds maintained in air-tight containers at subfreezing temperatures. There are over a thousand such banks worldwide, the great majority house seeds of economically important crops. At the Chicago Botanic Garden, seeds of native plants are being collected and stored in seed banks as a means of ex-situ (off-site) conservation, where biodiversity is conserved separately from its original habit.Offsite storage of species in peril, as well as preserving the native habitat, or in-situ conservation, are vital to species conservation as a whole.
Why seeds? Through drying and freezing, a seed’s life span can be extended on the order of decades and even centuries. As a general rule of thumb, for every 1% reduction in seed moisture content and every 5°C reduction in temperature, seed life span doubles. Because seeds take up little space, are often produced in abundance, and reflect the genetic diversity of an entire plant population, seed banking is an efficient and cost effective way to conserve the diversity of plant species.
How is seed collected? For each collection, we collect 3,000 to 20,000 viable seeds from a single population. Only 20% of the available seed on the day of collection is harvested to ensure that the population is not harmed. To adequately capture the genetic diversity of a population, seeds from a minimum of 50 individuals are collected. However, most collections housed in our bank are sampled from considerably more individuals.
Where do we collect? We currently concentrate collecting efforts in the tallgrass prairie region of the Midwest. Collections of species that are on our target list, but outside this region, are also sought. We collect at sites owned and managed at the federal, state, and county level, as well as NGO sites such as the Nature Conservancy and private property with permission.
What happens to the seeds? Once the seeds are collected, they are sent to the DNTPSB seed preparation laboratory to be accessioned and processed. They are dried for at least three weeks at 15% relative humidity at 15°C. Next, largely with the help of volunteers, the dried seeds are hand-cleaned, counted, weighed and frozen in air-tight foil bags and stored in the seed vault at -20°C. A small sample is x-rayed to determine if the seeds are viable.
What if something happens to your seed bank? A portion of each collection is housed at CBG. We also deposit some seed from each collection with other seed banks for redundant storage. MSBP and the National Center for Genetic Resource Preservation in Ft. Collins, CO are our alternative storage facilities.
How do you determine what species to collect? The DNTPSB aims to bank seeds of the entire vascular flora of the tallgrass prairie ecosystem capable of surviving cold storage. We are currently collecting 544 species selected for their importance for habitat restoration. Protocols for selecting these species can be found here. We also accept seeds of tallgrass prairie species not yet collected and represented in our seed bank. We do not collect threatened or endangered, globally rare, non-native, or crop species – and collect only from wild populations, not cultivated or restored. Click here for our 2017 Restoration Target Species list.
Can I use seeds collected and stored in the Dixon National Tallgrass Prairie Seed Bank? While seeds for the seed bank have been collected primarily for long-term conservation, we understand that access to these seeds by researchers and restoration practitioners is important for the conservation of native species. Please see our Seed Exchange Policy for more information about requesting seeds from the seed bank. Seeds added to our collection after 2012 will be available through GRIN.
How is the Seed Bank funded? Check out Resources for more information.