Final answer:
Cryopreservation is the storage of seeds at sub-zero temperatures, like the -18°C used for the seeds mentioned, which is ideal for long-term preservation by halting cellular activity and biological processes. The arctic climate of the Svalbard Global Seed Vault exemplifies this method's effectiveness.
Step-by-step explanation:
The type of storage used when seeds are dried and stored at -18 degrees Celsius is cryopreservation. This involves preserving cells or whole tissues by cooling them to sub-zero temperatures. The Svalbard Global Seed Vault is an example of a facility leveraging arctic conditions for this purpose, providing both long-term storage and short-term temperature stability. The arctic climate is particularly good for seed storage because it ensures the seeds remain below 0°C even if electricity fails, leveraging the naturally cold temperatures to maintain the viability of the seeds.
In lyophilization, combining cold exposure and desiccation effectively preserves items for extended periods with minimal damage. This is different from simple refrigeration, which reduces metabolic rates but does not stop microbial growth entirely. The ultra-low temperatures used in cryopreservation reduce metabolic activity so significantly that it allows for the long-term preservation of biological materials, such as seeds, by halting all cellular activity and biological processes.