Built like buildings, boab trees are life-savers with a chequered past



A boab tree in the Kimberley. Boab trees can live for thousands of years and their trunks hollow out as they get older.
Shutterstock

Gregory Moore, University of Melbourne

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When you are in the northern part of Western Australia, one of nature’s joys is seeing a large boab tree close up, perhaps for the first time.

The boab (Adansonia gregorii) is a native to this part of Australia, but is related to the broader group of species called boababs that live in Madagascar and Africa – but more on that connection later.

Boabs are also called bottle trees, the tree of life, boababs and Australian boababs. Some of the indigenous Australian names include gadawon and larrgadi.

From their iconic swollen trunks, to living up to 2,000 years and the many uses for their “superfood” fruits, here’s what makes boab trees so fascinating.



The Conversation

The ‘upside-down tree’: trunks that save lives and lock up prisoners

While the boab in Australia is not quite as well-documented as the African species, specimens have been recorded at over 1,000 years of age. Some living trees have been estimated to be nearer to 2,000 years old.

And while it’s difficult to age the trees, several specimens of the African species have been dated at 2,000 or more years old.

Australian boabs can grow up to 15 metres tall at maturity and have swollen, attention-grabbing trunks called a caudex, which may be up to five metres in diameter.

The African boab species, A. digitata, can be much taller, at 25 metres high and with a diameter of up to 15 metres.




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Iconic boab trees trace journeys of ancient Aboriginal people


In such dry continents, the caudex is a life-saver, often containing water, which was tapped by Indigenous folk. It has been estimated that some of these huge old trees can hold more than 100,000 litres of water in their trunks.

In Africa, these massive trunks have been used as shelters, homes, farm sheds and, more recently, even shops and bars.

Sadly in Australia, legend has it the huge trunks were used to make lock-ups for Indigenous people and other prisoners.

The infamous Boab Prison Tree, just south of Derby in Western Australia, was said to have once held Indigenous prisoners.
Shutterstock

It’s not just the trunk that can stop you in your tracks. The boab has a unique branching structure, one that looks more like a root system than a canopy.

Some locals in Africa will tell you the tree was dropped from heaven to earth and landed upside down. So the African species of boab is sometimes called the upside-down tree.

Boab fruits are ‘superfoods’ and its shell has many uses

A. gregorii, the Australian boab species, has large, attractive white flowers up to 75 millimetres in length. Its round fruits are edible and sought after by birds, mammals and humans. The fruit gives rise to some of the common names for the tree, such as monkey bread tree and dead rat tree. The latter comes from the appearance of older fruits in the canopy looking a bit like … well, dead rats?




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In fact, there’s great interest in fruits from the African species, A. digitata, which are considered a “superfood” because of their high levels of antioxidants, calcium, potassium, magnesium, fibre and vitamin C. It’s assumed many of these traits will be shared by the Australian boab, but there is little research as yet to prove it.

Fruit of the African boab tree fruit are initially covered in velvety fur.
Ton Rulkens/Wikimedia, CC BY-SA

The soft part of the fruit is surrounded by a hard, coconut-like shell that’s initially covered in a velvety fur. The hard shell has been used for cups and bowls, but has also been intricately carved and decorated by Aboriginal artists in Africa and Australia. If the seeds are left inside the fruit as it dries, they can be used for toys like rattles.

On both continents, Aboriginal people have eaten the white powder that surrounds the seeds. The leaves are rich in iron and the pulp from the fruits tastes like cream of tartar.

The Indigenous people of both continents were also well aware of the medicinal uses of the fruits. The bark and leaves of the trees also treat various ailments, but particularly those associated with digestive disorders.




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But at present there is very little modern research on the medicinal and dietary aspects of either the baobab or boab.

How the boab tree got to Australia

One of the mysteries surrounding the boab is how it got to Australia – the Australian species has clear affinities with related species in continental Africa and Madagascar.

A baobab tree, Adansonia digitata, in Tarangire National Park, Tanzania. Its journey from Africa to Australia remains a mystery.
Yoki/Wikimedia, CC BY-SA

There are three intriguing theories.

The first is that all of the boababs originate from the super-continent Gondwana – consisting of Africa, South America, Antarctica, Australia, India and Madagascar – before it fragmented almost 80 million years ago. But A. Gregorii and A. digitata are so similar genetically that, given the millions of years that have elapsed, this theory is now in question.

The second theory comes from recent DNA analysis of the species. It suggests they separated more recently, perhaps only 70,000 years ago, which raises the question, were humans involved in their journey? But did they come to Australia from Africa, or from Australia to Africa? The latter is a less likely scenario given the direction of ocean currents.

And the third theory is that fruits arrived on the Australian shore after an epic ocean voyage from Africa.




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Boabs are usually found in the remote outback of Australia, but in 2008, a large 750-year-old boab was transported from Warmun in the Kimberley to Perth and transplanted in Kings Park.

Transplanting such a large tree is both daunting and fraught, with a high chance of failure, but the deciduousness and growth habit of the boab gave some cause for optimism about a successful outcome. For the reward of having a large old boab growing in Perth, it would be worth it.

After a period of stress, the tree appears to be coming good, reflecting the toughness of the species.

A large, mature boab is a splendid tree of arid Australia that inspires awe in all who experience them close up. They really are a beauty and a bottler of a tree!


Sign up to Beating Around the Bush, a series that profiles native plants: part gardening column, part dispatches from country, entirely Australian.The Conversation

Gregory Moore, Doctor of Botany, University of Melbourne

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

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This centuries-old river red gum is a local legend – here’s why it’s worth fighting for


Euan Ritchie, Deakin University

Sign up to the Beating Around the Bush newsletter here, and suggest a plant we should cover at batb@theconversation.edu.au.


In Dr Seuss’s The Lorax, his titular character famously said:

I am the Lorax. I speak for the trees. I speak for the trees, for the trees have no tongues.

In the midst of a global extinction crisis, the Lorax’s call to preserve what is precious couldn’t be more apt. The greatest threat to the survival of species globally continues to be habitat destruction and modification.




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A potential and local victim of this ongoing environmental catastrophe is a single tree, and a tree I have a deep personal connection with. The tree I refer to is Bulleen’s iconic 300-year-old river red gum (Eucalyptus camaldulensis).

To me this tree has been a constant in my life. While everything else has changed around me, it has stood there, solid, just as solid as its red gum fibres are known to be.

As a child I fondly remember looking up at this tree in awe, as we’d often stop at the nearby service station on a hot summer’s day to buy a cold drink or ice-cream on the way to Saturday sport, the nearby Birrarung (Yarra River), or my grandmother’s house.



The Conversation

Bulleen’s majestic river red gum

It’s estimated to be approximately 20 metres in height with a canopy spread of 17 metres. And its trunk measures a whopping two metres across.

The tree is thought to be the oldest remnant of a once substantial red gum forest, and was saved by a local resident when the rest of the area was cleared for the construction of a service station.

It now faces destruction, as it is within the preferred path of construction for Victoria’s North East link.




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While the measurements of this tree are impressive, the splendour and value for me is that it has survived for so long and, in more recent times, against tremendous odds.

Surviving against all odds

The Bulleen red gum stands beside one of Melbourne’s busiest roads and the immediate area is covered with concrete and bitumen. The tree’s roots and health have therefore been challenged for a long time, and yet this massive red gum stands, as if in defiance of the modern world and the development that has encircled it.

Since this tree has survived for so long, it undoubtedly holds a special connection with so many: the Wurundjeri-willam people of the Kulin Nation, members of Australia’s famed Heidelberg school of artists who lived and worked in the near vicinty, everyday commuters that have driven or walked by or stopped to admire it, or the war verteran Nevin Phillips who once apparently defended it with his rifle against it being chainsawed.

Very old trees such as Bulleen’s river red gum deserve our respect and protection, for these trees have substantial environmental, economic and cultural value.
National Trust

Further proof of the value of this tree to so many is that it was awarded The National Trust of Australia’s (Victoria) 2019 Victorian Tree of the Year.

Why we must speak for and save old trees

I grew up near this tree and, like the Lorax, I would like to speak for it.
Trees as old as the Bulleen river red gum are now increasingly rare in our world, and beyond their strong personal and cultural values, including in some places as Aboriginal birthing sites, they are tremendously important for other reasons as well.




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These trees provide shade and help keep our cities cooler, improve our mental health and wellbeing, and store considerable amounts of carbon aiding our fight against climate change.

Perhaps most importantly, under their bark and in their cracks and hollows, they provide homes for many of Australia’s precious but increasingly imperilled native wildlife, including bats, birds, possums and gliders, snakes and lizards, insects and spiders.

These homes are prime wildlife real estate, especially in our big cities, where such large old trees are vanishingly rare but where considerable wildlife, common and threatened, still persists. And yet more could survive with a helping hand from us.

A powerful owl chick in a tree hollow, in outer Melbourne.
John White (Deakin University)

As cities like Melbourne continue to grow around the world, there will be more and more cases where arguments of progress are used to justify the further destruction of what nature remains. But progress shouldn’t come at any cost, and in the case of preserving iconic and valuable trees such as Bulleen’s river red gum, it would seem there’s more than enough reasons to ensure this tree’s life and its many values continue.

Perhaps again the wise sage, the Lorax, says it best.

Unless someone like you cares a whole awful lot, Nothing is going to get better. It’s not.


Sign up to Beating Around the Bush, a series that profiles native plants: part gardening column, part dispatches from country, entirely Australian.The Conversation

Euan Ritchie, Associate Professor in Wildlife Ecology and Conservation, Centre for Integrative Ecology, School of Life & Environmental Sciences, Deakin University

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

The sexy gum: a love story



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Dr Michael Whitehead is campaigning to rename the Gimlet Gum to the Sexy Gum.
Author provided (No reuse)

Michael Whitehead, University of Melbourne

It is perhaps poetic that a region most famous for its lack of trees lies so close to one of Australia’s greatest tree-based spectacles. The Nullarbor Plain, our famous, flat, featureless expanse is literally named for its absence of trees (“arbor” being Latin for tree).

And if you ever get to drive west along the longest stretch of dead-straight road across this iconic landscape, you will come to know the highlights that characterise the experience: the cliff-top views of the Great Australian Bight and the idiosyncratic roadhouses.




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Then finally, a landscape of low shrubs gives way to mallee trees and woodland vegetation. Somewhere between Caiguna and Fraser Range you’ll see your first Eucalyptus salubris, also known as a gimlet gum, or joorderee by the Ngadju people.

It was on a recent botanical research trip chasing scraggly emu bushes that I stumbled upon, and fell in love with, Eucalytpus salubris. The trunks were what instantly caught my eye, slender with graceful twists, all the more observable for the brilliantly shining coppery bark.



The Conversation

The sexy gum

The tree first appears in European record during early explorations crossing east of the Darling Range. Then, it was called “cable gum” after the gently twisting grooves in the trunks.

Later the tree was given the common name of “gimlet” after a form of hand drill. Unfortunately this name stuck and today the species remains “gimlet” – a wholly unattractive moniker for such a splendid tree.

But our imaginations need not be held hostage by the stubborn colonialists who named our flora after such dreary things.




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That’s why I’m campaigning to update the common name to something more universal, more marketable, something truer to its sensual twists and smooth, glowing bronze surface.

Eucalytpus salubris is the Sexy Gum.

Love goes where my eucalypt grows

E. salubris is a dominant species forming woodlands on deep soils east of the Darling Range. And while much of its former range in the Wheatbelt of Western Australia has been cleared, extensive populations of E. salubris remain in the astonishing stronghold of the Great Western Woodlands.

Those who have walked in a mature woodland understand the pleasure of wandering unimpeded in the shade of widely spaced trees.

Widely spaced trees of the Great Western Woodlands.
Keren Gila/Wikimedia, CC BY

The Great Western Woodlands offers this experience on a grand scale. At around 16 million hectares they are the largest tracts of intact temperate woodlands on Earth, occupying an area larger than England and Wales combined.

And it is not just size that is impressive about these woodlands.

The Great Western Woodlands are a renowned hotspot for eucalypt diversity, home to around 30% of Australia’s eucalypt species in just 2% of its land area.

As one of the more common species throughout the area, E. salubris plays a critical ecological role, providing habitat for several threatened bird species including the rotund and charismatic Mallee fowl.




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Due to its remoteness and unreliable rainfall, the Great Western Woodlands has avoided the widescale grazing and clearing that has degraded neighbouring areas to the south and west.

But despite the value of this untouched landscape, most of the area is “orphan country” with no formal management policies in place. Some 60% of the Great Western Woodlands is unallocated crown land, unmanaged and open access.

This is a plus for visitors wanting to experience it now, but raises important concerns about the long-term security of the area.

While remote, threats to the Great Western Woodlands do exist. Chief among them is the increasing frequency and intensity of bush fires.

Most eucalypts are resprouters with the ability to regenerate burned canopies from buds under the bark. There are, however a number of species, such as Mountain Ash, that will die following canopy fires and can only regenerate from the soil seedbank (called “reseeders”).




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E. salubris, the sexy gum, is one such reseeder. While the traditional occupants of the land used fire as a land management tool, they also knew E. salubris woodland took hundreds of years to regenerate and were careful to never burn the canopy of old growth forests.

The eye-pleasing spectacle of mature open Eucalytpus salubris woodland above red soil and blue-bush therefore exists today thanks to careful management from this era, and deserves careful handling to ensure its ongoing future.

An ambassador for the Great Western Woodlands

Late in the day, when the Sun’s glancing rays light up the bark of E. salubris, punctuating a pastel blue-green woodland with glowing streaks like molten metal, it’s hard to not stop for at least a moment and be impressed.

And while E. salubris’ role as keystone species might be important ecologically, I think the Sexy Gum can be similarly important as ambassador and draw-card for the Great Western Woodlands.

Its golden tones and metallic lustre conjures just the appropriate impression for the WA Goldfields. It is totally Instagram-able, and I don’t think it’s a hard sell to convince people E. salubris is a spectacle worth getting off the beaten track for.The Conversation

Michael Whitehead, Research Fellow in Evolutionary Ecology, University of Melbourne

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

A detailed eucalypt family tree helps us see how they came to dominate Australia



File 20190312 86690 1fiqo8w.jpg?ixlib=rb 1.1
In Australia you can have any tree you want, as long as it’s a eucalypt.
Shutterstock

Andrew Thornhill, James Cook University

Eucalypts dominate Australia’s landscape like no other plant group in the world.

Europe’s pine forests consist of many different types of trees. North America’s forests change over the width of the continent, from redwood, to pine and oak, to deserts and grassland. Africa is a mixture of savannah, rainforest and desert. South America has rainforests that contain the most diversity of trees in one place. Antarctica has tree fossils.

But in Australia we have the eucalypts, an informal name for three plant genera: Angophora, Corymbia and Eucalyptus. They are the dominant tree in great diversity just about everywhere, except for a small region of mulga, rainforest and some deserts.

My research, published today, has sequenced the DNA of more than 700 eucalypt species to map how they came to dominate the continent. We found eucalypts have been in Australia for at least 60 million years, but a comparatively recent explosion in diversity 2 million years ago is the secret to their spread across southern Australia.

Hundreds of species

The oldest known Eucalyptus macrofossil, from Patagonia in South America, is 52 million years old. The fossil pollen record also provides evidence of eucalypts in Australia for 45 million years, with the oldest specimen coming from Bass Strait.

Despite the antiquity of the eucalypts, researchers assumed they did not begin to spread around Australia until the continent began drying up around 20 million years ago, when Australia was covered in rainforests. But once drier environmental conditions kicked in, the eucalypts seized their chance and took over, especially in southeastern Australia.

Eucalypts are classified by their various characteristics, including the number of buds.
Mary and Andrew/flickr, CC BY-NC-SA

There are over 800 described species of eucalypts. Most of them are native only to Australia, although some have managed to naturally escape further north to New Guinea, Timor and Indonesia. Many eucalypts have been introduced to other parts of the world, including California, where Aussie eucalypts make cameos in Hollywood movies.

Eucalypts can grow as tall trees, as various multi-trunk or single-trunk trees, or in rare cases as shrubs. The combination of main characteristics – such as leaf shape, fruit shape, bud number and bark type – provided botanists with enough evidence to describe 800 species and estimate how they were all related to each other, a field of science known as “taxonomy”.

Since the 1990s and early 2000s, taxonomy has been slightly superseded by a new field called “phylogenetics”. This is the study of how organisms are related to each other using DNA, which produces something akin to a family tree.

Phylogenetics still relies on the species to be named though, so there is something to sample. New scientific fields rely on the old. There have been a number of eucalypt phylogenetic studies over the years, but none have ever sampled all of the eucalypt species in one phylogeny.




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Our new paper in Australian Systematic Botany aimed to change that. We attempted to genetically sample every described eucalypt species and place them in one phylogeny to determine how they are related to each other. We sampled 711 species (86% of all eucalypts) as well as rainforest species considered most closely related to the eucalypts.

We also dated the phylogeny by time-stamping certain parts using the ages of the fossils mentioned above. This allowed us to estimate how old eucalypt groups are and when they separated from each other in the past.

Not so ancient

We found that the eucalypts are an old group that date back at least 60 million years. This aligns with previous studies and the fossil record. However, a lot of the diversification in the Eucalyptus genus has happened only in the last 2 million years.

Gum trees are iconic Australian eucalypts.
Shutterstock

Hundreds of species have appeared very recently in evolutionary history. Studies on other organisms have shown rapid diversification, but none of them compare to the eucalypts. Many species of the eucalypt forests of southeastern Australia are new in evolutionary terms (10 million years or less).

This includes many of the tall eucalypts that grow in the wet forests of southern Australia. They are not, as was previously assumed, ancient remnants from Gondwana, a supercontinent that gradually broke up between 180 million and 45 million years ago and resulted in the continents of Australia, Africa, South America and Antarctica, as well as India, New Zealand, New Guinea and New Caledonia.

The eucalypts that grow natively overseas have only made it out from Australia in the last 2 million years or less. Other groups in the eucalypts such as Angophora and Corymbia didn’t exhibit the same rapid diversification as the Eucalyptus species.




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What we confirmed with the fossil record using our phylogeny is that until very recently, and I mean in terms of the Earth being 4 billion years old, the vegetation of southeastern Australia was vastly different.

At some point in the last 2-10 million years the Eucalyptus arrived in new environmental conditions. They thrived, they most likely helped spread fire to wipe out their competition, and they then rapidly changed their physical form to give us the many species that we see today.

Very few other groups in the world have made this amount of change so quickly, and arguably dramatically. The east coast of Australia would look very different if it wasn’t dominated by gum trees.

The next time you’re in a eucalypt forest, take a look around and notice all of the different types of bark and gumnuts and leaves on the trees, and know that all of that diversity has happened quite recently, but with a deep and long link to trees that once grew in Gondwana.

They have been highly advantageous, highly adaptable and, with the exception of a small number of species, are uniquely Australian. They are, as the press would put it, “a great Australian success story”.The Conversation

Andrew Thornhill, Research botanist, James Cook University

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

Greenwashing: corporate tree planting generates goodwill but may sometimes harm the planet



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Missing the wood for the trees.
iDraw/Shutterstock

Benjamin Neimark, Lancaster University

Trees do a lot more for us than you probably think. Their roots prevent soil from eroding, their canopies provide shade and their leaves decompose into nutrients for crops, which feed livestock. Trees provide homes for a diverse range of wildlife and tree crops, such as coffee, rubber, and hardwoods, support countless livelihoods and entire economies. Trees also mark boundaries and hold immense spiritual, cultural and social value for smallholder communities around the world.

In the 1980s, charities proposed planting more trees to halt “desertification” in the Sahara Desert. This involved “afforestation” – planting trees where they had not grown for a while and “reforestation” – replacing recently lost tree cover.

Today the idea is growing strong, and an array of private companies from adult website Pornhub (yes, Pornhub) to clothing brand Ten Tree are using trees as a marketing tool.




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Saving face or saving forests?

Businesses can offset their environmental impact by planting trees or supporting other forms of habitat restoration, so as to “pay off” the damage they cause locally. As climate change escalates, trees are in vogue for their potential to soak up the carbon dioxide we keep putting in the atmosphere.

The United Nations (UN) has even adopted a scheme for offering local communities and governments some sort of financial payout for saving trees from deforestation. This “economy of repair” has been adopted by some of the largest companies in their commitments to corporate social responsibility. One such programme is the Green Belt Movement – a Kenyan conservation NGO started by the late professor and Nobel Prize recipient Wangari Maathai.

Tree planting around the Sahara Desert has overwhelmingly relied on local efforts rather than businesses.
Niels Polderman/Shutterstock

Maathai’s original mission was to empower local people, particularly women, to overcome inequality through leading forest restoration and resisting the expanding Sahara Desert. Despite the involvement of charities and businesses, research has suggested that in programmes like these, it is farmers and local people, not companies, which make the biggest contributions to planting new trees. Since local people also inherit responsibility for them, it’s important that projects devised by outside parties are planned and executed wisely, and in the community’s interest.




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While some may argue that tree planting is a win-win for the environment whoever does it, offsetting is just another way of corporate greenwashing. Environmental damage in one place cannot somehow be fixed by repairing habitats elsewhere, sometimes on the other side of the world.

Here are some of the ways in which indiscriminate tree planting can cause more harm than good.

Plantations are not forests

Diverse forests are often cleared for agricultural production or industrial use, and replaced by uniform stands of the same species selected because of their ability to grow fast.

Tropical forests in some cases take up to 65 years to regrow and their diversity cannot be replicated by a monoculture of reforested plots.

Ecologically illiterate

Reforestation and afforestation schemes must decide which species are appropriate to plant – native or exotic, multi-purpose or fast growing, naturally regenerating forests or managed plantations. Sometimes the wrong species are selected and Eucalyptus (Eucalyptus globulus) is one such poor choice.

Eucalyptus is usually chosen because it is fast growing and economically valuable. Yet, it is exotic to many places it is now planted and requires lots of water, which drains the water table and competes with native crops.

In Europe, replacing broad-leafed native oak trees with faster growing conifers has meant that forest cover on the continent is 10% greater than it was before the industrial revolution. However, the new trees are not as good at trapping carbon but do trap heat more efficiently, contributing to global warming. Clearly, tree planting without due caution can do more harm than good.

Trees need care – lots of it

Tree species take a long time to grow and need continual care. However, tree planting schemes usually “plant and go” –- meaning they do not put resources into managing the trees after they are placed into the ground. Young trees are particularly vulnerable to disease and competition for light and nutrients and if not cared for, will eventually die.

Newly planted tree saplings may need three to five years of frequent watering to survive.
A3pfamily/Shutterstock

Trees are political

Trees planted by states or private donors may choose sites without consulting local communities, ignoring any of their customary land rights and management regimes. This locally-owned land may be in fallow or have different economic, cultural or spiritual uses.

Blundering into planting in these places may exacerbate tensions over land tenure, spreading disinterest in tree care and stewardship. Dispossessed locals may move to existing forests and clear land for food production. Tenure rights over trees are also not always owned by whole households either, but divided between gender. Planting trees and asking questions later may sow tensions over land ownership for long after the project departs.

It’s no surprise that trees are on the green economy agenda, but this does not necessarily mean that planting them is “green” or helpful for social harmony. Allowing trees to regrow naturally is not always effective either, as trees are unlikely to survive on their own. Community involvement is therefore crucial.

This means real consultation over site and species selection, property rights over the trees, their products, and the land they grow in and who takes on the labour to keep the trees alive after they are planted. If companies are serious about planting trees then they need to care about the communities that live with them and not just their own reputations.The Conversation

Benjamin Neimark, Senior Lecturer, Lancaster Environment Centre, Lancaster University

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

Lord of the forest: New Zealand’s most sacred tree is under threat from disease, but response is slow



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Tāne Mahuta is New Zealand’s most sacred tree, but its days will be numbered if it is infected with kauri dieback disease.
from http://www.shutterstock.com, CC BY-SA

Matthew Hall, Victoria University of Wellington

Tāne Mahuta is Aotearoa New Zealand’s largest living being – but the 45m tall, 2,500-year-old kauri tree is under severe threat from a devastating disease.

Nearly a decade after the discovery of kauri dieback disease, it is continuing to spread largely unchecked through the northern part of the North Island. Thousands of kauri trees have likely been infected and are now dead or dying. The Waipoua forest, home of Tāne Mahuta and many other majestic kauri, is reported to be one of the worst affected areas.

For Māori, who trace their whakapapa (lineage) to the origins of the earth, Tāne Mahuta is kin. The threat of losing this tree should electrify the fight against kauri dieback.




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Call to close the forest

Named after Tāne, the son of Ranginui the sky father and Papatūanuku the earth mother, Tāne Mahuta is a highly revered taonga, or treasure. In Māori mythology, it was Tāne who brought trees and birds to earth.

The loss of this ancestor, with a presence that has been known to move some to tears, is incalculable.

Kauri dieback has been recorded metres from this ancient tree, despite the best efforts of a prevention programme that has been in place since 2009. Much of the focus of the programme has been on encouraging behaviour change by forest users (following paths, washing boots) and upgrading tracks (from mud to boardwalks). A new national pest management plan proposes more of the same.

As part of a prevention programme to limit the spread of kauri dieback, visitors to kauri forests are encouraged to spray their shoes with a disinfectant.
Eli Duke/WIkimedia Commons, CC BY-SA
Signs remind visitors in the Waitākere Ranges about precautions against the spread of kauri dieback disease.
from Wikimedia Commons, CC BY-SA

In my view, the most notable, and frustrating, aspect of this programme is the significant resistance to close kauri forest tracks to people, who, along with wild pigs, are one of the major vectors of the disease.

Te Kawerau ā Maki, a Māori tribal group with mana whenua (customary authority) over the land of the Waitākere forest in the Auckland region, have maintained a consistent stance that the only way to protect kauri forests is to close them to humans. In November 2017, they placed a rāhui (temporary closure) over the entire forest area, severely frustrated by the lack of effective action to control kauri dieback by Auckland Council.

A rāhui is not legally enforceable, and it was largely ignored by forest users who continued to enter and spread the disease. Eventually, six months later, Auckland Council voted to close the majority of tracks, but Te Kawerau ā Maki have viewed this as too little, and possibly too late.

Keeping the forest open

In a similar laggardly vein, the Department of Conservation has only just put forward a proposal to close or partially close 24 kauri forest tracks. This proposal is currently going through a consultation process, which seems inappropriate when dealing with an immediate biosecurity crisis.

The proposal does not include the Waipoua forest and the track that leads to Tāne Mahuta, or to other significant kauri such as Te Matua Ngahere. The department says:

the decision to propose track closures is not taken lightly, but has been considered in situations where there is high kauri dieback risk, low visitor use, high upgrade and ongoing maintenance costs, and a similar experience provided in the vicinity.

Tāne mahuta draws hundreds of thousands of tourists to the Waipoua forest area. This, combined with the fact that forest tracks are generally in good condition has led to the decision to keep the forest open. For now, the tangata whenua (local Māori with authority over land) support it.

Tāne Mahuta draws hundreds of thousands of visitors to the kauri forests in the north of New Zealand.
from http://www.shutterstock.com, CC BY-SA

Relinquishing our claims

Although we know that our human presence in kauri forests will lead to the certain death of the trees, many people still wish to venture into the forests, to walk or to hunt, regardless of the consequences.

Whether conscious or not, the value assessment here must be that the right of kauri trees to live and flourish is of lesser value than some fleeting recreation on a weekend afternoon. As people kept blindly tramping into the Waitākere forest, infection rates increased from 8% to 19% in just five years.

What I find most disturbing here is that government agencies tasked with preserving the “intrinsic values” of native species are prepared to let this happen for pragmatic and economic reasons. This is one of those situations where competing values can’t be balanced.

The life and flourishing of kauri must be prioritised above all else, whatever the economic or recreational hit. This means letting go of our claim to kauri trees as “natural and recreational resources” and acknowledging them for what they are – our living, spiritual, intelligent kin.

Kauri or kiwifruit

Pragmatically, our assistance to kauri also necessitates that we re-assess the value we place on the survival of kauri from an economic perspective.

Funding of less than NZ$2 million per year for the kauri dieback programme pales in comparison to the magnitude of the response to recent agricultural biosecurity threats.

In 2010, a huge response to the incursion of a microbial pathogen (Pseudomonas syringae pv. actinidiae, or Psa) in kiwifruit vines saw a NZ$50 million fund created to fight the disease.

In 2015, after a single Queensland fruit fly was caught in a trap in February, a large coordinated response, with local, restrictive biosecurity control orders in place, resulted in eradication in October, at a cost of NZ$13.6 million.

With such funds, it would be much easier to enforce the closure of kauri forests, until more long-term measures, such as improving genetic resistance, become possible.

At the end of last year, Minister for Forestry Shane Jones was quoted expressing a similar opinion, following the government’s announcement that it would attempt to eradicate the cow disease Mycoplasma bovis.

If it’s possible for us to move swiftly and cull diseased cows and stop the transport of potentially diseased cows off private farms, we need a similar level of vigour in safeguarding areas where our kauri are still strong.

The ConversationFor the survival of Tāne Mahuta, we should close off kauri forests immediately and boost funding for the implementation of the dieback management programme.

Matthew Hall, Associate Director, Research Services, Victoria University of Wellington

This article was originally published on The Conversation. Read the original article.

Baobab trees have more than 300 uses but they’re dying in Africa



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An ancient giant.
Shutterstock

Aida Cuní Sanchez, University of York

Nine of 13 of Africa’s oldest and largest baobab trees have died in the past decade, it has been reported. These trees, aged between 1,100 and 2,500 years, appear to be victims of climate change. Scientists speculate that warming temperatures have either killed the trees directly or have made them weaker and more susceptible to drought, diseases, fire or wind.

Old baobabs are not the only trees which are affected by climatic changes. Ponderosa pine and Pinyon forests in the American West are dying at an increasing rate as the summers get warmer in the region. In Hawaii the famous Ohi’a trees are also dying at faster rates than previously recorded.

There are nine species of baobab trees in the world: one in mainland Africa, Adansonia digitata, (the species that can grow to the largest size and to the oldest age), six in Madagascar, and one in Australia. The mainland African baobab was named after the French botanist Michel Adanson, who described the baobab trees in Senegal.

The African baobab is a remarkable species. Not only because of it’s size and lifespan but also in the special way it grows multiple fused stems. In the space between these stems (called false cavities) bark grows, which is unique to the baobab.

Since baobabs produce only faint growth rings, the researchers used radiocarbon dating to analyse samples taken from different parts of each tree’s trunk and determined that the oldest (which is now dead) was more that 2,500-years-old.

Adansonia digitata can get to 2,500-years-old.
Bernard Dupont/Flickr, CC BY-SA

They also have more than 300 uses. The leaves, rich in iron, can be boiled and eaten like spinach. The seeds can be roasted to make a coffee substitute or pressed to make oil for cooking or cosmetics. The fruit pulp has six times more vitamin C than oranges, making it an important nutritional complement in Africa and in the European, US and Canadian markets.

Locally, fruit pulp is made into juice, jam, or fermented to make beer. The young seedlings have a taproot which can be eaten like a carrot. The flowers are also edible. The roots can be used to make red dye, and the bark to make ropes and baskets.

Baobab fruit:
Author provided

Baobabs also have medicinal properties, and their hollow trunks can be used to store water. Baobab crowns also provide shade, making them an idea place for a market in many rural villages. And of course, the trade in baobab products provides an income for local communities.

Baobab trees also play a big part in the cultural life of their communities, being at the centre of many African oral stories. They even appear in The Little Prince.

A spiritual force.
Shutterstock

Cultivating baobab

Baobab trees are not only useful to humans, they are key ecosystem elements in the dry African savannas. Importantly, baobab trees keep soil conditions humid, favour nutrient recycling and avoid soil erosion. They also act as an important source of food, water and shelter for a wide range of animals, including birds, lizards, monkeys and even elephants – which can eat their bark to provide some moisture when there is no water nearby. The flowers are pollinated by bats, which travel long distances to feed on their nectar. Numerous insects also live on the baobab tree.

Easy to fit inside.
Shutterstock

Ancient as they are, baobab trees can be cultivated, as some communities in West Africa have done for generations. Some farmers are discouraged by the fact that they can take 15-20 years to fruit – but recent research has shown by grafting the branches of fruiting trees to seedlings they can fruit in five years.

Many “indigenous” trees show great variation in fruit morphological and nutritional properties – and it takes years of research and selection to find the best varieties for cultivation. This process, called domestication, does not refer to genetic engineering, but the selection and cultivation of the best trees of those available in nature. It seems straightforward, but it takes time to find the best trees – meanwhile many of them are dying.

The ConversationThe death of these oldest and largest baobab trees is very sad, but hopefully the news will motivate us to protect the world’s remaining large baobabs and start a process of close monitoring of their health. And, hopefully, if scientists are able to perfect the process of identifying the best trees to cultivate, one day they will become as common in our supermarkets as apples or oranges.

Aida Cuní Sanchez, Postdoctoral Research Associate, University of York

This article was originally published on The Conversation. Read the original article.