A seed bank is a facility that stores seeds from many plant species and populations to preserve their genetic material for future use. It is a form of ex situ conservation, meaning conservation outside a species’ natural habitat.
How Does a Seed Bank Work?
Seeds are collected from wild or cultivated plant populations. Collectors aim to sample many individuals so that the stored seeds represent as much of the population’s genetic diversity as possible.
The seeds are usually cleaned, dried and stored at low temperatures. These conditions reduce respiration and other metabolic activity, allowing suitable seeds to remain viable for long periods. Samples are periodically tested for their ability to germinate, and new plants may be grown to produce replacement seeds when viability declines.
Stored seeds can later be used to:
- reintroduce a species after extinction in part of its natural range;
- restore degraded ecosystems;
- support scientific research;
- provide genetic variation for crop breeding, including alleles for disease resistance or tolerance of environmental change.
Seed banks store germ plasm: living genetic resources that can be used to produce new organisms. They therefore provide protection against habitat destruction, over-exploitation, climate change and other causes of biodiversity loss.
However, seed banking has limitations. Seeds from some plant species cannot survive drying or freezing, and storage does not conserve interactions between a plant and other organisms in its ecosystem. Small or unrepresentative samples may also fail to preserve the full gene pool. Seed banks should therefore complement in situ conservation, such as protecting species in nature reserves, rather than replace it.
Exam Technique
This is assessed at both SL and HL in A4.2 Conservation of biodiversity. In an “explain” response, identify seed banking as ex situ conservation, describe the storage of germ plasm, and link preserved genetic diversity to possible reintroduction. Avoid the misconception that storing seeds conserves an entire ecosystem; it primarily conserves plant genetic material.
