Decades-old seed bank helps revive Stirling Range's rare flora after 2018–19 bushfires

Seeds collected years before catastrophic bushfires ripped through Western Australia’s Stirling Range National Park are giving some of the world’s rarest plants a second chance. The park, a hotspot with about 1,500 native flora species, lost 26 threatened species to the 2018 and 2019 fires, including 18 listed as critically endangered.

Among the most imperilled was Banksia montana. “Before the fire, we had 37 mature individuals left in the world, and they were all restricted to the Eastern Stirling Range, and all of those were burnt in the fire,” said Sarah Barrett, a conservation officer with the Department of Biodiversity, Conservation and Attractions.

In the immediate aftermath, teams located tiny seedlings, fenced them to deter grazing animals and applied phosphite to bolster defences against dieback. Off the mountain, recovery was bolstered by decades of “insurance” seed collections held at the Western Australian Seed Centre in Perth.

“We’ve been fortunate that we’ve been collecting seed over that period,” Barrett said. “Some of the populations that we collected seed from are now extinct.” Andrew Crawford, the centre’s collections manager, said samples are prepared for longevity.

Seeds are sealed in foil bags to fix moisture content, then placed in a seed vault — a large freezer kept at minus-20 degrees — and held “until we need them at some point in the future to help with the recovery of those species.” To rebuild numbers, seed production sites were set up in Porongurup National Park and Redmond State Forest.

Research scientist Rebecca Dillon said 1,000 plants from 14 species were grown at each site and later transplanted into the Stirling Range, with helicopters used to reach remote areas. Dillon said the work is showing positive results, but a drying climate remains a major threat.

Surveys before and after the fires indicate plants in natural populations are shifting away from north-facing ridges toward cooler, wetter back slopes. Years on, the team continues its on- and off-mountain efforts, from phosphite spraying and protective fencing to renewed seed collection as established plants begin producing seed.