A gene bank is what scientists call efforts to conserve genetic diversity, in order either to keep species from becoming endangered or extinct, or to preserve the variety within a species. For both plants and animals, the ideal gene bank is a natural habitat that is protected from destruction.
The University of California arboretum includes a cryogenic seed bank developed by neurobiologist, Harold Koopowitz. Koopowitz's cryogenic seed bank is a kind of ex situ gene bank that takes little space and is easy to maintain. It involves, simply enough, collecting and labeling seeds and placing them in a freezer that is kept at minus 40 degrees centigrade. Finding the proper storage conditions and temperature, and testing for the viability of seeds after various periods of time in the freezer, took some time, but the technique is now a proven one. Koopowitz started the first cryogenic seed bank in the United States, and he has since encouraged many others to follow suit. He has also been a leader in convincing other arboreta to expand beyond their traditional role - providing a place for the study of plant species and their growth - and to get more directly involved in the conservation of endangered plant species. While the preservation of natural habitats is still the most important goal, ex situ measures such as these are needed while those habitats remain at risk.