Backyard gardeners around the world are helping to save Australia’s deeply ancient Wollemi pine


Heidi Zimmer, Southern Cross University and Catherine Offord

As bushfires blackened forests last summer, one tree species was protected by a specialist team of firefighters: the Wollemi pine.

These trees have a deeply ancient lineage dating back to when dinosaurs walked Gondwana 100 million years ago. Back then, rainforests – including Wollemi pines (or their cousins) – covered what became Australia.

So when a handful of Wollemi pines were discovered alive in 1994 on the brink of extinction, it caused a frenzy of interest that has barely died down among plant enthusiasts.

How firefighters saved the Wollemi pine from the bushfires.

Today, fewer than 100 mature pines are left in the wild. But their exact location is one of the best kept secrets in Australian plant conservation, to protect them from pathogens such as the root-rotting phytophthora that might hitch a ride on human visitors.

But while rare in nature, our ongoing research with citizen scientists is finding Wollemi pines grow in backyards all over the world, in a range of environments, and this information can inform how we can protect them in the wild.

From Gondwana to the garden

The Wollemi pine is considered the iconic poster-child for plant conservation. It’s an unusual-looking plant – each wild tree has many trunks covered in bark resembling bubbling chocolate and branches of lime or grey-green fern-like leaves. And in the wild, they grow to more than 40 metres tall.

The species is a member of the southern conifer family Araucariaceae, and its cousins include the monkey puzzle tree and the Norfolk Island pine. While considered a rainforest tree, many remaining in the wild exist between rainforest and dry eucalypt woodland, on the ledges of a sandstone gorge.

Wollemi pines can stretch 40 metres in the wild.
Heidi Zimmer.

Since the Wollemi pine was discovered 26 years ago, the protection effort has been intense, focusing on conservation in the wild.

One of the first strategies was cultivation. Horticultural scientists at the Australian Botanic Garden Mount Annan (Sydney) worked out how to propagate the species so it could be grown and enjoyed in gardens, reducing the risk of illegal visitation in the wild.




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After the Australian Botanic Garden established a basic “insurance population” of plants propagated from the wild trees, some of the first cultivated Wollemi pines were distributed to botanic gardens in Australia and overseas, including in the UK’s Royal Botanic Gardens Kew.

In 2005, Wollemi pines were auctioned to the public at a Sothebys Auction. Since then, they’ve been exported to many nurseries around the world, and now grow in many public and private gardens.

I spy a Wollemi pine

When plants are very rare in the wild, or are very restricted in their distributions, conservation away from the site (ex situ) can play an important role in their survival.

This includes seed banking, translocation (establishing new populations of rare plants in new locations) and cultivation for the nursery trade.




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Enter our I Spy A Wollemi Pine project. Fifteen years after the Wollemi pine became available for sale, our study asks people to report where Wollemi pines are growing in gardens across the world.

So far, results from the online survey have revealed the species grows across 27 different countries, from Australia to Russia, and the UK to Peru.

The tallest trees so far – stretching to 7 metres tall (though dwarfed by their wild counterparts) – have been reported from the UK. To date, 987 people have contributed data about Wollemi pines.

Wollemi pines growing in Coates Wood, United Kingdom.
Ellen McHale © RBG Kew.

What we can learn

Reading comments from survey participants – from “Has survived minus 10 degrees” to “I just love it” – has been a source of interest and joy for us researchers.

When the survey is finished, we’ll analyse the responses to understand what influences the growth of this species, such as different climates and soils.

Knowing how Wollemi pines grow in other parts of the world will provide gardening tips for home growers, but more importantly it will inform future conservation efforts in the wild in the face of climate change.




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For example, this research will provide information on what environments the Wollemi pine can tolerate. We’re discovering the hottest, coldest, wettest and driest places on earth this species can survive in.

This information can help us find places to establish new populations of Wollemi pines. It may also provide clues on the evolutionary history of this species and how it managed to survive multiple ice ages and other dramatic climate changes in deep history.

Conservation with cultivation

Conserving Wollemi pines in backyards is not quite the same as Wollemi pines in the wild – in the same way its important to have pandas in the wild, and not just in zoos. But using cultivation for conservation does mean these species have much greater distribution today than they have ever had in the past.

In fact, this isn’t the first time a rare tree has ended up in gardens. The dawn redwood, thought to be extinct in the wild, was rediscovered in China in the 1940s and can now be found in gardens across the world.

And the internet is a great place to foster conservation. In online forums, people share every stage of their Wollemi babies’ growth, from seed germination to pine cone production.




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This love and connection to Wollemi pines might even help address “plant blindness”: the propensity for people to see, recognise and focus on animals rather than plants, despite plants being central to providing us with food, the air we breathe and our climate.

So, as more species are threatened with extinction every day, everyone’s actions – even in their own backyards or online – can make a difference.


If you have a Wollemi pine in your backyard, or know of a Wollemi pine in a park or garden, and would like to get involved in our citizen science survey, please click here.The Conversation

Heidi Zimmer, Research associate, Southern Cross University and Catherine Offord, Senior Principal Research Scientist

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The phoenix factor: what home gardeners can learn from nature’s rebirth after fire


Kingsley Dixon, Curtin University

A startling phenomenon occurs after a bushfire tears through a landscape. From the blackened soil springs an extraordinary natural revival – synchronised germination that carpets the landscape in flowers and colour.

So what is it in bushfires that gives plants this kiss of life? The answer is smoke, and it is increasingly transforming everything from large-scale land regeneration to nurseries and home gardening.

The mystery of seed germination

Burnt plants survive bushfires in various ways. Some are protected by woody rootstocks and bark-coated stems; others resprout from underground buds. But most plants awaken their soil seed bank, which may have lain dormant for decades, or even a century.

However, this smoke-induced seed germination is not easily replicated by humans trying to grow the plants themselves. Traditionally, many native Australian flora species – from fringe-lilies to flannel flowers and trigger plants – could not be grown easily or at all from seed.

The fringe-lily, the seed of which has been found to germinate after smoke treatment.
Flickr

In recent decades this has meant the plants were absent from restoration programs and home gardens, reducing biodiversity.

In 1989, South African botanist and double-PhD Dr Johannes de Lange grappled with a similar conundrum. He was trying to save the critically rare Audonia capitata, which was down to a handful of plants growing around Cape Town. The seed he collected could not be germinated, even after heat and ash treatments from fire. Extinction looked inevitable.

But during a small experimental fire, a wind change enveloped de Langer in thick
smoke. With watering eyes, he realised that smoke might be the mysterious phoenix factor that would coax the seeds to life. By 1990 he had shown puffing smoke onto soil germinated his rare species in astonishing numbers.

The technique is simple. Create a smouldering fire of dry and green leafy material and pass the smoke into an enclosed area where seed has been sown into seed trays or spread as a thin layer. Leave for one hour and water sparingly for ten days to prevent the smoke from washing out of the seed mix. The rest is up to nature.

Diagram showing the various ways that smoke is applied to seeds.
Supplied by Simone Pedrini

Taking smoke germination to the world

Soon after the de Lange discovery, I visited the Kirstenbosch National Botanic Garden in Cape Town. I was shown a few trays of seedlings out the back – some from seeds treated with smoke, some without. The difference was stark. Smoke-treated seeds produced a riot of green, compared to others that resulted in sparse, straggling seedlings.

A tray of seedlings where seed was treated with smoke, left, compared to a non-treated tray.
Supplied by author

But was smoke just an isolated African phenomenon, I wondered? Would 150 years of frustrated efforts to germinate some of Australia’s most spectacular and colourful species – from grevillea and fan-flowers to rare native heaths – also be transformed by smoke?

At first, the answer appeared to be no, as every attempt with Australian wildflower seed failed. But after many trials, which I oversaw as Director of Science at the Western Australian Botanic Garden, success came in 1993. Extra time in the smoke house and a serendipitous failure in the automated watering system resulted in the germination of 25 different species with seedlings. Some were thought to have never been germinated by humans before, such as wild-picked yellow bells (Geleznowia verrucosa) or the giant feather rush (Loxocarya gigas).




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This discovery meant for the first time smoke could be used for difficult-to-germinate species for the home gardener and cut flower growers. These days more than 400 species of native seeds, and potentially more than 1,000, respond to smoke treatment. They include kangaroo paw, cotton-tails, spinifex, native bush food tomatoes and fragrant boronias.

Highway plantings, mine site restoration and, importantly, efforts to save threatened plant species now also benefit greatly from the smoke germination technique. For example, smoke houses are now a regular part of many nurseries, which also purchase smoke water to soak seeds for sowing later.

Kangaroo paw seeds respond well to smoke treatment.
Supplied by the author

In mine site restoration, direct application of smoke to seeds dramatically improves germination performance. This translates into multimillion-dollar savings in the cost of seed.

Smoke is also a powerful research tool used to audit native soil seed banks, which includes demonstrating the adverse affects of prescribed burning in winter and spring on native species survival.

Collaboration with research groups in the US, China, Europe and South America has expanded the use of smoke to germinate similarly stubborn seed around the world.

So what is smoke’s secret ingredient?

In 2013, an Australian research team made a breakthrough in determining which of the 4,000 chemicals in a puff of smoke resulted in such starting germination. They patented the chemical and published the discovery in the journal Science.

The smoke chemical, part of the butenolide group of molecules, was named karrikinolide, inspired by the local Indigenous Noongar word for smoke, karrik.

Karrikinolide is no shrinking violet of a molecule: just half a teaspoon is enough to germinate a hectare of bushland, which equates to 20 million seeds.




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Smoke is sold to home gardeners and for commercial use in the form of smoke water, smoke-impregnated disks, or smoke granules. All contain the magical karrikinolide molecule.

Why not try it at home?

Home gardeners can try smoking their own seeds – but what you burn matters. Wood smoke can be toxic to seeds. Making your own smoke from leafy material and dry straw ensures you have the right combustible materials for germination.

At least 400 native seed species, and possibly up to 1,000, have been found to respond to smoke treatment.
Supplied by author

For the home gardener, having a bottle of smoke water on hand or constructing your own smokehouse can make all the difference to germinating many species – including those stubborn parsley seeds. To find out more, a webinar at this link shows you how to use smoke and even construct your own smoke apparatus.The Conversation

Kingsley Dixon, John Curtin Distinguished Professor, Curtin University

This article is republished from The Conversation under a Creative Commons license. Read the original article.