Out of the Freezer, into the Fire

Date posted: 17 August 2021

Repatriation of a rare pea from the UK Seed Bank for bushfire recovery in the Adelaide Hills

By Dan Duval and Jenny Guerin from the SA Seed Conservation Centre. This story was originally published in Australasian Plant Conservation - Bulletin of the Australian Network for Plant Conservation Inc. Volume 30 Number 1 June – August 2021, pp19-20.

Across Australia in recent years, the need to access seeds stored in seed banks has arisen.

However, when seeds are collected from threatened plants for long‑term storage, how they will be used is not always pre-determined.

In 2009, seeds from the nationally vulnerable Clover Glycine (Glycine latrobeana), pictured above, were collected from the Mount Lofty Ranges by staff at the South Australian Seed Conservation Centre (SASCC) for safekeeping. The practice is part of the South Australian seed‑banking program.

A decade later, an uncontrolled bushfire in the Adelaide Hills burnt through 25,000 hectares in the Cudlee Creek region.

Within this region there were small fragments of remnant vegetation that contained Clover Glycine - as well as other significant threatened plant species.

And although we had a small collection of Clover Glycine seeds recently collected from private bushland within the fire scar, the quantities stored were insufficient for recovery work.

Fortunately, in 2009, a larger collection of 1,200 seeds from the Mount Bold Reservoir Water Reserve had been sent to our international partner, the Millennium Seed Bank at the Royal Botanic Gardens, Kew, UK for storage. Various seed collections are stored on our behalf, for conservation purposes, by the Millennium Seed Bank (MBS) under an international partnership agreement.

Seeds coming home

In April 2020 we asked for 250 of the 1,200 seeds MSB held in long‑term storage in order to grow plants to support the bushfire recovery.

Typically, we aim to duplicate the number of conservation collections with MSB as a safeguard against loss of any collections held by one institution. We have utilised collections in long‑term storage for several recovery projects in recent years.

The partial repatriation of collections from long‑term storage at MSB was a precedent for the Australian Seed Bank partners - and also a precedent for Australian Biosecurity.

The importation of seeds for a threatened plant species of wild origin in Australia is a rare occurrence and generated logistical questions for their (re‑) importation.

Growing on...

The seeds arrived in August 2020, and 230 plants were propagated for planting back into the fire-affected area in 2021. They were also planted into the seed orchard within Adelaide Botanic Garden - an area specifically set aside to nurture threatened plants for seed production.

By February 2021, nearly 800 seeds were harvested from the newly grown plants for ongoing recovery work.

The propagation of plants for reintroduction in this project was initially considered as an opportunity to augment sites and populations in the post‑fire environment. It was a supporting contingency; the expectation was that most populations of this rare pea that occur within the fire scar would respond favourably to the bushfire and grow again.

However, during monitoring of known population sites in the spring and summer of 2020, all sites had markedly reduced plant numbers.... or no plants present at all.

In one bushland reserve, no plants could be detected at any of the three recorded population sites.

It is hoped that better plant numbers will be observed in spring 2021 and that populations will gradually recover.

Leafy Greenhood grows again

Similar observations have been recorded for other threatened species within these bushfire affected reserves.

A small, disjunct population of the nationally vulnerable Leafy Greenhood (Pterostylis cucullatassp. sylvicola) occurs in the Lobethal Bushland Park council reserve. In spring 2019, a few weeks before the bushfire, 144 plants were recorded.

But in spring 2020, no plants could be detected. The fire intensity was evident by the thick layer of ash and, to confirm the lack of plant re‑emergence, soil was excavated in one cage that previously contained multiple individual plants. No tubers were detected.

Fortunately, Leafy Greenhood seeds from this population are held in long term storage in the SA seed bank, housed within Adelaide Botanic Garden.

They were used to grow this threatened orchid species and in August 2021, 134 individuals were planted in the Adelaide Hills, with more that will be ready to plant in 2022 and 2023.

The summer fires of 2019‑2020 led to native vegetation recovery projects, including a regional project to restore Clover Glycine and Leafy Greenhoods into their natural habitat.

The historic seed collections from this region have proved to be very significant today, and highlight the value of the ex‑situ conservation work undertaken by seed banks.

This project has been kindly supported by the National Bushfire Recovery program through a partnership with the Hills and Fleurieu Landscape Board.