We are often questioned about the fate of the seeds held in the Dixon National Tallgrass Prairie Seed Bank (DNTPSB). Can seeds be retrieved once they enter the bank and how? Who has access to the seeds? Do we monitor the viability of the seeds once they are placed in cold storage? What happens if seeds begin to lose viability? Before tackling these important questions, let me first answer a more basic one – Why place native seeds into long-term storage?
Since most temperate seeds have orthodox seed storage behavior (seeds that remain viable for a long period of time with proper processing and storage), seed banks provide an ex-situ (off site) option for conserving our native flora. Approximately 95% of the genetic diversity represented in a population is captured in the seeds of as few as 50 individual plants which, in many cases, amount to a handful of seeds. So, given that a small quantity of seeds holds the genetic diversity present in a population and has the capability of retaining that genetic diversity for long periods of time, seed banking is a viable and efficient plant conservation strategy; especially considering the impacts global climate change poses to our nature preserves and restorations. But, the question that many people ask is “What then?” - What happens to the seeds after they disappear into the dark, frozen recesses of the seed vault?
First of all, not all of the seeds in the collection are held at DNTPSB. Half of the seeds are sent to other seed banks for redundant, or backup, storage. Of the 1/2 that remains at DNTPSB, 1/4 is designated for long-term conservation and the remaining portion is designated for research and eventual germination testing. The property owner of the site where the seeds were collected has full access to the entire collection held at DNTPSB. However, since the owner agreed to place the seeds into the seed bank and the purpose of the seed bank is long-term conservation of native species, we encourage and assume that at least the portion designated for conservation will remain in the seed bank. The seeds designated for research and germination are available in small quantities for non-profits and students or other researchers to use in various research or restoration projects at the discretion of seed bank staff. We also retain this collection for future germination testing. A small fee is imposed for seed bank “withdrawals”, except for the owner of the site where the seeds were collected. This fee will help cover the costs of replacing the seeds if quantities run low. Ideally, replacing seeds entails recollecting from the original site or growing plants to the reproductive stage and harvesting the first generation to be placed back into the seed bank.
Currently we do not have the resources to perform comprehensive germination tests on our seed collections. Fortunately, we share many of our seeds with larger seed banks such as Millennium Seed Bank at the Royal Botanic Garden, Kew, UK which do test collections for viability by running germination tests every 10 years. Through their testing, we can keep track of the viability of many of our collections. The longevity of many native seeds in seed banks is not known, but with careful management, this knowledge is being acquired.