Seed Banking: Preserving Genetic Diversity

Why provenance matters

Every tree population carries a genetic signature shaped by centuries of selection in one place. A coastal oak has genes for wind, salt, and compact form. An inland oak fifty kilometres away has genes for height and canopy competition.

Plant the inland seed on the coast and the trees snap. Their genes never met that wind.

This is why provenance, the geographic origin of seed, is the single biggest decision in reforestation. Local seed brings soil chemistry, rainfall, frost timing, and pest pressure already written into the embryo.

Climate change muddies the rule. If your site is heating, the best-adapted genotype may now sit slightly south or downslope. Some programmes hedge with "assisted migration," sourcing 10 to 30 percent of seed from warmer populations a few hundred metres lower in elevation.

The core principle holds. Match the seed to the conditions the trees will face, not the conditions you remember from childhood.

Collection ethics

Wild seed collection is a privilege. Strip a tree clean and you starve the jays, mice, and next year's seedlings.

The working rule:

Take no more than 10 to 20 percent of the crop in any year.
Collect from at least 15 to 20 parent trees per species per site.
Skip isolated trees. Their seed is likely selfed and inbred.
Skip range-edge trees unless your site is also marginal.

Record location, date, species, and parent identity for every collection. GPS coordinates, elevation, aspect, soil notes. Without that record the seed loses most of its value. You cannot prove its origin, and a restoration nursery 200 km away has no way to match it to a planting site.

Timing

Timing is species-specific and tight. For wind-dispersed species the window between ripe and gone is sometimes three days.

For fleshy fruits, you race the birds. Visit candidate trees twice a week through ripening. Watch for colour shifts, softening pulp, the first acorns on the ground. Masanobu Fukuoka called this patient observation. Seed work rewards it more than almost anything else.

Drying and storage

Seeds split into two camps. Orthodox seeds tolerate drying and cold. Recalcitrant seeds, including most oaks, chestnuts, and tropicals, die if you dry them below a critical moisture point.

Know which camp your species is in before you collect. That one fact decides everything.

Orthodox protocol. Clean off pulp, wings, and debris. Dry slowly in shade with good airflow to 5 to 8 percent moisture. Store in airtight jars with silica gel at 1 to 5 degrees Celsius, or freeze at minus 20 for the long bank. Properly dried, orthodox seed stays viable for 5 to 50 years.

Recalcitrant protocol. Sow immediately if you can. If you must hold them, keep them moist in damp sand or vermiculite at 5 to 10 degrees for temperate species. Check weekly for mould and early germination. Sow as soon as the ground is ready.

Recalcitrant species are the hardest to bank and the easiest to lose. Protect their parent populations on the ground.

Community seed banks

Institutional vaults like Kew's Millennium Seed Bank are insurance at global scale. For local restoration, community seed banks do more useful work.

A community bank is a cool dry room, jars, desiccant, labels, and a notebook. The real investment is training: identification, phenology, drying, records.

These banks do more than store. They build identification skills, connect collectors with planters, and move genetic material between landowners. Wangari Maathai's Green Belt Movement ran a decentralised network of village nurseries that worked this way, with local women collecting and growing native species adapted to their own hillside.

Partner with a local botanic garden or herbarium for ongoing quality control. They will catch the misidentifications before you plant ten hectares of the wrong subspecies.

A small bank can run from one shed and a chest freezer. A regional bank serving multiple counties needs cold-room redundancy and a backup power supply. Scale the building to the catchment you actually serve.

Climate resilience

Within-species variation is enormous. In provenance trials, some genotypes grow twice as fast as their neighbours. Some survive droughts that kill 90 percent of the population.

That variation is the engine of adaptation. It only exists in genetically diverse populations. A restoration that plants seed from one parent tree is a genetic monoculture waiting to fail.

Seed banks and living populations work together. Wild populations keep evolving but can burn, drown, or be bulldozed for a highway. Banked seed is a snapshot, frozen in time, and cannot adapt on its own. The resilient strategy runs both at once.

For fast-turnover pioneer species, protecting living populations is usually enough. They flower in three years and adapt with every generation.

For slow climax species like native oaks or baobabs, which take 30 to 60 years to fruit, banked seed is irreplaceable insurance. Lose the parent stand and you lose centuries of selection at once.