The 50 beautiful Australian plants at greatest risk of extinction — and how to save them


Caley’s grevillea (Grevillea caleyi) occurs in Sydney. It needs fire to germinate but burns are hard to carry out near urban areas.
Tony Auld, Author provided

Jennifer Silcock, The University of Queensland; Jaana Dielenberg, Charles Darwin University; Roderick John Fensham, The University of Queensland, and Teghan Collingwood, The University of QueenslandAs far as odds go, things don’t look promising for the slender-nerved acacia (Acacia leptoneura), a spiky plant with classic yellow-ball wattle flowers. With most of its habitat in Western Australia’s wheat belt cleared for agriculture, it was considered extinct for more than 160 years.

Now, just two plants are known in the world, and they’re not even in the same place. This species is among many Australian plants that have come perilously close to extinction.

To help prevent the loss of any native plant species, we’ve assembled a massive evidence base for more than 750 plants listed as critically endangered or endangered. Of these, we’ve identified the 50 at greatest risk of extinction.

The good news is for most of these imperilled plants, we already have the knowledge and techniques needed to conserve them. We’ve devised an action plan that’s relatively easy to implement, but requires long-term funding and commitment.

What’s driving the loss?

There are 1,384 plant species and subspecies listed as threatened at a national level. Twelve Australian plant species are considered probably extinct and a further 21 species possibly extinct, while 206 are officially listed as critically endangered.

Yellow wattle
Two known plants of slender nerved acacia (Acacia leptoneura) remain, about 1 kilometre apart. Propagation attempts have been unsuccessful and the genetic diversity is probably very low.
Joel Collins, Author provided

Australian plants were used, managed and celebrated by Australia’s First Nations people for at least 60,000 years, but since European colonisation, they’ve been beset by a range of threats.

Land clearing, the introduction of alien plants, animals, diseases, and interruptions to ecological processes such as fire patterns and flooding have taken a heavy toll on many species. This is particularly the case in the more densely populated eastern and southern parts of the continent.

Close-up of yellow flower
Ironstone pixie mop (Petrophile latericola) occurs on a soil type that’s been heavily cleared for agriculture, and is suspected to be susceptible to an introduced root-rot fungus. In 2020 fewer than 200 plants remained, in poor condition.
Andrew Crawford, Author provided

Things aren’t improving. Scientists recently compiled long-term monitoring of more than 100 threatened plant species at 600 sites nationally. And they found populations had declined on average by 72% between 1995 and 2017.

This is a very steep rate of decline, much greater than for threatened mammal or bird populations.




Read more:
Australia-first research reveals staggering loss of threatened plants over 20 years


On the brink

Many species listed as threatened aren’t receiving targeted conservation action or even baseline monitoring, so an important first step in preventing extinctions was identifying the species at greatest risk.

To find the top 50, we looked at the evidence: all available published and unpublished information and expert surveys of over 120 botanists and land managers.
They’re targeted by our Action Plan for Australia’s Imperilled Plants.

Action Plan for Australia’s Imperilled Plants.

Thirty of the species in the plan have fewer than 50 mature individual plants remaining.

And 33 are known only from a single location, such as the Grampians pincushion-lily (Borya mirabilis), which occurs on one rocky outcrop in Victoria. This means the entire population could be destroyed by a single event, such as a major bushfire.

A dead-looking gum tree on agricultural land
About 2,000 Morrisby’s gums were growing in the early 1990s, but by 2016 fewer than 50 remained. Climate change and damage from insects and animals threaten those left. Protecting trees with fencing has led to new seedlings.
Magali Wright, Author provided
Fewer than 10 lax leek-orchids (Prasophyllum laxum) remain. Declines are ongoing due to drought and wildfire, and the South Australian species only occurs on private property not managed for conservation. Proposed recovery actions include habitat protection and establishing the orchid and its mycorrhizal fungi in conservation reserves.
Shane Graves, Author provided
Fewer than 15 woods well spyridium (Spyridium fontis-woodii) shrubs remain on a single roadside in South Australia. Research into threats and germination requirements is urgently needed, plus translocation to conservation reserves.
Daniel Duval/South Australian Seed Conservation Centre, Author provided

So how can we protect them?

Some of the common management actions we’ve proposed include:

  • preventing further loss of species’ habitat. This is the most important action required at a national scale
  • regularly monitoring populations to better understand how species respond to threats and management actions
  • safely trialling appropriate fire management regimes, such as burning in areas where fires have been suppressed
  • investing in disease research and management, to combat the threat of phytophthora (root-rot fungus) and myrtle rust, which damages leaves
  • propagating and moving species to establish plants at new sites, to boost the size of wild populations, or to increase genetic diversity
  • protecting plants from grazing and browsing animals, such as feral goats and rabbits, and sometimes from native animals such as kangaroos.
Once common, the dwarf spider-orchid (Caladenia pumila) wasn’t seen for over 80 years until two individual plants were found. Despite intensive management, no natural recruitment has occurred. Propagation attempts have successfully produced 100 seedlings and 11 mature plants from seed. This photo shows botanist Marc Freestone hand-pollinating dwarf spider-orchids.
Marc Freestone, Author provided
Only 21 mature plants of Gillingarra grevillea (Grevillea sp. Gillingarra) remain on a disturbed, weedy rail reserve in southwestern WA. Half the population was destroyed in 2011 due to railway maintenance and flooding. Habitat protection and restoration, and translocations to conservation reserves are needed to ensure its survival.
Andrew Crawford, Author provided

Another common issue is lack of recruitment, meaning there’s no young plants coming up to replace the old ones when they die. Sometimes this is because the processes that triggered these plants to flower, release seed or germinate are no longer occurring. This can include things like fire of a particular intensity or the right season.

Unfortunately, for some plants we don’t yet know what triggers are required, and further research is essential to establish this.

Now we need the political will

Our plan is for anyone involved in threatened flora management, including federal, state, territory and local government groups, First Nations, environment and community conservation groups, and anyone with one of these plants on their land.

The Border Ranges lined fern (Antrophyum austroqueenslandicum) and its habitat are exceedingly rare. It’s threatened by drought and climate change, and fewer than 50 plants remain in NSW. If the threat of illegal collection can be controlled, the species would benefit from re-introduction to Queensland’s Lamington National Park.
Lui Weber, Author provided

Plants make Australian landscapes unique — over 90% of our plant species are found nowhere else in the world. They’re also the backbone of our ecosystems, creating the rich and varied habitats for our iconic fauna to live in. Plants underpin and enrich our lives every day.

Now we have an effective plan to conserve the Australian plants at the greatest risk of extinction. What’s needed is the political will and resourcing to act in time.




Read more:
Undocumented plant extinctions are a big problem in Australia – here’s why they go unnoticed


The Conversation


Jennifer Silcock, Post-doctoral research fellow, The University of Queensland; Jaana Dielenberg, University Fellow, Charles Darwin University; Roderick John Fensham, Associate Professor of Biological Sciences, The University of Queensland, and Teghan Collingwood, Research Technician, The University of Queensland

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

Scientists are more likely to study bold and beautiful blooms, but ugly flowers matter too


Myricaria germanica is a rare and endangered species hit hard by climate change, but little research is undertaken to help save it.
Martino Adamo, Author provided

Kingsley Dixon, Curtin UniversityWe all love gardens with beautiful flowers and leafy plants, choosing colourful species to plant in and around our homes. Plant scientists, however, may have fallen for the same trick in what they choose to research.

Our research, published today in Nature Plants, found there’s a clear bias among scientists toward visually striking plants. This means they’re more likely chosen for scientific study and conservation efforts, regardless of their ecological or evolutionary significance.

To our surprise, colour played a major role skewing researcher bias. White, red and pink flowers were more likely to feature in research literature than those with dull, or green and brown flowers. Blue plants — the rarest colour in nature — received most research attention.

But does this bias matter? Plants worldwide are facing mass extinction due to environmental threats such as climate change. Now, more than ever, the human-induced tide of extinction means scientists need to be more fair-handed in ensuring all species have a fighting chance at survival.

Hidden plants in carpets of wildflowers

I was part of an international team that sifted through 280 research papers from 1975 to 2020, and analysed 113 plant species found in the southwestern Alps in Europe.

The Alps is a global biodiversity hotspot and the subject of almost 200 years of intensive plant science. But climate change is now creating hotter conditions, threatening many of its rarest species.

White flower with mountains in background
Edelweiss is a charismatic plant of the Alps that heralds spring.
Shutterstock

Carpeted in snow for much of the year, the brief yet explosive flowering of Europe’s alpine flora following the thaw is a joy to behold. Who was not bewitched when Julie Andrews danced in an alpine meadow in its full spring wildflower livery in The Sound of Music? Or when she sung “edelweiss”, one of the charismatic plants of the Alps that heralds spring?




Read more:
People are ‘blind’ to plants, and that’s bad news for conservation


Hidden in these carpets of bright blue gentians and Delphiniums, vibrant daisies and orchids, are tiny or dull plants. This includes small sedges (Carex species), lady’s mantle (Alchemilla species) or the snake lily (Fritillaria) with its sanguine drooping flowers on thin stems.

Many of these “uncharismatic plants” are also rare or important ecological species, yet garner little attention from scientists and the public.

Close-up of a blue flower
Bellflowers (Campanula) are conspicuous and prominent in the Alps.
Martino Adamo, Author provided

The plants scientists prefer

The study asked if scientists were impartial to good-looking plants. We tested whether there was a relationship between research focus on plant species and characteristics, such as the colour, shape and prominence of species.

Along with a bias towards colourful flowers, we found accessible and conspicuous flowers were among those most studied (outside of plants required for human food or medicine).

Blue flowers
Bold and beautiful flowers in alpine meadows win scientific attention.
Martino Adamo, Author provided

This includes tall, prominent Delphinium and larkspurs, both well-known garden delights with well-displayed, vibrant flowers that often verge on fluorescent. Stem height also contributed to how readily a plant was researched, as it determines a plant’s ability to stand out among others. This includes tall bellflowers (Campanula species) and orchids.

But interestingly, a plant’s rarity didn’t significantly influence research attention. Charismatic orchids, for example, figured prominently despite rarer, less obvious species growing nearby, such as tiny sedges (Cypreaceae) and grass species.

The consequences of plant favouritism

This bias may steer conservation efforts away from plants that, while less visually pleasing, are more important to the health of the overall ecosystem or in need of urgent conservation.

In this time of urgent conservation, controlling our bias in plant science is critical. While the world list of threatened species (the IUCN RED List) should be the basis for guiding global plant conservation, the practice is often far from science based.

Mat rush with brown flowers
Mat rushes are home for rare native sun moths.
Shutterstock

We often don’t know how important a species is until it’s thoroughly researched, and losing an unnoticed species could mean the loss of a keystone plant.

In Australia, for example, milkweeds (Asclepiadaceae) are an important food source for butterflies and caterpillars, while grassy mat rushes (dull-flowered Lomandra species) are now known to be the home for rare native sun moths. From habitats to food, these plants provide foundational ecological services, yet many milkweed and mat rush species are rare, and largely neglected in conservation research.




Read more:
‘Majestic, stunning, intriguing and bizarre’: New Guinea has 13,634 species of plants, and these are some of our favourites


Likewise, we can count on one hand the number of scientists who work on creepy fungal-like organisms called “slime molds”, compared to the platoons of scientists who work on the most glamorous of plants: the orchids.

Yet, slime molds, with their extraordinary ability to live without cell walls and to float their nuclei in a pulsating jelly of cytoplasm, could hold keys to all sorts of remarkable scientific discoveries.

Yellow slime on tree trunk
Slime molds could hold the key to many scientific discoveries, but the organisms are understudied.
Shutterstock

We need to love our boring plants

Our study shows the need to take aesthetic biases more explicitly into consideration in science and in the choice of species studied, for the best conservation and ecological outcomes.

While our study didn’t venture into Australia, the principle holds true: we should be more vigilant in all parts of the conservation process, from the science to listing species for protection under the law. (Attractiveness bias may affect public interest here, too.)

So next time you go for a bushwalk, think about the plants you may have trodden on because they weren’t worth a second glance. They may be important to native insects, improve soil health or critical for a healthy bushland.




Read more:
These 3 tips will help you create a thriving pollinator-friendly garden this winter


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.

5 remarkable stories of flora and fauna in the aftermath of Australia’s horror bushfire season



hamiltonphillipa/iNaturalist, CC BY-NC-SA

Will Cornwell, UNSW; Casey Kirchhoff, UNSW, and Mark Ooi, UNSW

Around one year ago, Australia’s Black Summer bushfire season ended, leaving more than 8 million hectares across south-east Australia a mix of charcoal, ash and smoke. An estimated three billion animals were killed or displaced, not including invertebrates.

The impact of the fires on biodiversity was too vast for professional scientists alone to collect data. So in the face of this massive challenge, we set up a community (citizen) science project through the iNaturalist website to help paint a more complete picture of which species are bouncing back — and which are not.

Almost 400 community scientists living near or travelling across the firegrounds have recorded their observations of flora and fauna in the aftermath, from finding fresh wombat droppings in blackened forests, to hearing the croaks of healthy tree frogs in a dam choked with debris and ash.

Each observation is a story of survival against the odds, or of tragedy. Here are five we consider particularly remarkable.

Greater gliders after Australia’s largest ever fire

The Gospers Mountain fire in New South Wales was the biggest forest fire in Australian history, razing an area seven times the size of Singapore. This meant there nothing in history scientists could draw from to predict the animals’ response.

So it came as a huge surprise when a community scientist observed greater gliders deep within the heart of the Gospers Mountain firegrounds in Wollemi National Park, far from unburned habitat. Greater gliders are listed as “vulnerable” under national environment law. They’re nocturnal and live in hollow-bearing trees.

A greater glider with shining eyes at night
A citizen scientist snapped this photo of a greater glider in the heart of the the Gospers Mountain firegrounds.
Mike Letnic/iNaturalist, CC BY-NC

How gliders survived the fire is still unknown. Could they have hidden in deep hollows of trees where the temperature is relatively cooler while the fire front passed? And what would they have eaten afterwards? Greater gliders usually feed on young leaves and flowers, but these foods are very rare in the post-fire environment.

Finding these gliders shows how there’s still so much to learn about the resilience of species in the face of even the most devastating fires, especially as bushfires are forecast to become more frequent.

Rare pink flowers burnishing the firegrounds

The giant scale of the 2019-20 fires means post-fire flowering is on display in grand and gorgeous fashion. This is a feature of many native plant species which need fire to stimulate growth.

Excitingly, community scientists recorded a long-dormant species, the pink flannel flower (Actinotus forsythii), that’s now turning vast areas of the Blue Mountains pink.

Pink flannel flowers are bushfire ephemerals, which means their seeds only germinate after fire.
Margaret Sky/iNaturalist, CC BY-NC

Pink flannel flowers are not considered threatened, but they are very rarely seen.

Individuals of this species spend most of their life as a seed in the soil. Seeds require a chemical found in bushfire smoke, and the right seasonal temperatures, to germinate.

Rediscovering the midge orchid

Much of Australia’s amazing biodiversity is extremely local. Some species, particularly plants, exist only in a single valley or ridge. The Black Summer fires destroyed the entire range of 100 Australian plant species, incinerating the above-ground parts of every individual. How well a species regenerates after fire determines whether it recovers, or is rendered extinct.

The midge orchid.
Nick Lambert/iNaturalist, CC BY-NC

One of these is a species of midge orchid, which grows in a small area of Gibraltar Range National Park, NSW.

All of the midge orchid’s known sites are thought to have burned in late 2019. The species fate was unknown until two separate community scientists photographed it at five sites in January 2021, showing its recovery.

Like many of Australia’s terrestrial orchids, this species has an underground tuber (storage organ) which may have helped part of it avoid the flames’ lethal heat.




Read more:
After last summer’s fires, the bell tolls for Australia’s endangered mountain bells


Don’t forget about insects

Despite their incredible diversity and tremendous value to society, insects tend to be the forgotten victims of bushfires and other environmental disasters.

Many trillions of invertebrates would have been killed in the fires of last summer. A common sight during and after the bushfire season was a deposit of dead insects washed ashore. Some died from the flames and heat, while others died having drowned trying to escape.

Dead insects washed up on the beach was a common sight in the fire aftermath.
BlueBowerStudio/iNaturalist, CC BY-NC

One dead insect deposit — one of hundreds that washed up near Bermagui, NSW on Christmas Eve — included a range of species that have critical interactions with other organisms.

This includes orchid dupe wasps (Lissopimpla excelsa), the only known pollinator of the orchid genus Cryptostylis. Transverse ladybirds (Coccinella transversalis), an important predator of agricultural pests such as aphids, also washed up. As did metallic shield bugs (Scutiphora pedicellata), spectacular iridescent jewel bugs that come in green and blue hues.

Some insects died from the flames and heat, while others died having drowned trying to escape the flames.
BlueBowerStudio/iNaturalist, CC BY-NC

The unlikely survival of the Kaputar slug

Creatures such as kangaroos or birds have a chance to flee bushfires, but smaller, less mobile species such as native slugs and snails have a much tougher time of surviving.

The 2019-2020 bushfire season significantly threatened the brilliantly coloured Mount Kaputar pink slug, found only on the slopes of Mount Kaputar, NSW. When fires ripped through the national park in October and November 2019, conservationists feared the slug may have been entirely wiped out.




Read more:
Photos from the field: zooming in on Australia’s hidden world of exquisite mites, snails and beetles


But park ranger surveys in January 2020 found at least 60 individuals managed to survive, likely by sheltering in damp rock crevices. Community scientists have spotted more individuals since then, such as the one pictured here found in September 2020.

But the slug isn’t out of the woods yet, and more monitoring is required to ensure the population is not declining.

Bright pink slug
A community scientist spotted this rare slug in firegrounds.
Taylor/iNaturalist, CC BY-NC

Continuing this work

While community scientists have been documenting amazing stories of recovery all across Australia, there are still many species which haven’t been observed since the fires. Many more have been observed only at a single site.

The Snowy River westringia (Westringia cremnophila), for instance, is a rare flowering shrub found on cliffs in Snowy River National Park, Victoria. No one has reported observing it since the fire.

So far these community scientist observations have contributed to one scientific paper, and three more documenting the ability for species to recover post-fire are in process.

Recovery from Black Summer is likely to take decades, and preparing a body of scientific data on post-fire recovery is vital to inform conservation efforts after this and future fires. We need more observations to continue this important work.




Read more:
Summer bushfires: how are the plant and animal survivors 6 months on? We mapped their recovery


The Conversation


Will Cornwell, Associate Professor in Ecology and Evolution, UNSW; Casey Kirchhoff, PhD Candidate, UNSW, and Mark Ooi, Senior Research Fellow, UNSW

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

Undocumented plant extinctions are a big problem in Australia – here’s why they go unnoticed



Matchstick banksia (Banksia cuneate). There are only about 500 of these plants left in the wild at 11 different sites, with much of its habitat having been historically cleared for agriculture.
Andrew Crawford/Threatened Species Hub

David Coates, University of Western Australia

A recent survey on the world’s plants found a shocking number have gone extinct – 571 since 1750. And this is likely to be a stark underestimate. Not all plants have been discovered, so it’s likely other plants have gone extinct before researchers know they’re at risk, or even know they exist.

In Australia, the situation is just as dire. The Threatened Species Recovery Hub recently conducted two evaluations that aren’t yet published of extinct plants in Australia. They found 38 have been lost over the last 170 years, such as the Daintree River banana (Musa fitzalanii) and the fringed spider-orchid (Caladenia thysanochila).




Read more:
‘Plant blindness’ is obscuring the extinction crisis for non-animal species


But uncertainty about the number of plant extinctions, in addition to the 38 confirmed, is an ongoing concern.

Both studies pointed out the actual number of extinctions is likely to be far more than those recognised in formal lists produced by the Commonwealth and state and territory agencies.

For example, there is still a high rate of discovery of new plant species in Australia. More than 1,600 plants were discovered between 2009 and 2015, and an estimated 10% are still yet to be discovered.

The extinction of Australian plants is considered most likely to have occurred in areas where there has been major loss and degradation of native bushland. This includes significant areas in southern Australia that have been cleared for agriculture and intensive urbanisation around major cities.

Many of these extinct plants would have had very restricted geographic ranges. And botanical collections were limited across many parts of Australia before broad scale land clearing and habitat change.

Why extinction goes undocumented

There is already one well recognised Australian plant extinction, a shrub in Phillip Island (Streblorrhiza speciosa), which was never formally recognised on any Australian threatened species list.

Black magic grevillea (Grevilla calliantha) is known from only six populations within a range of 8 square kilometres. In the wild the species is threatened by frequent fire, habitat loss, invasive weeds, herbicide overspray, grazing animals and phytophthora dieback.
Dave Coates

Researchers also note there are Australian plants that are not listed as extinct, but have not been collected for 50 years or more.

While undocumented extinction is an increasing concern, the recent re-assessment of current lists of extinct plants has provided a more positive outcome.

The re-assessment found a number of plants previously considered to be extinct are not actually extinct. This includes plants that have been re-discovered since 1980, and where there has been confusion over plant names. Diel’s wattle (Acacia prismifolia), for instance, was recently rediscovered in Western Australia.




Read more:
‘Revolutionary change’ needed to stop unprecedented global extinction crisis


A significant challenge for accurately assessing plant extinction relates to the difficulties in surveying and detecting them in the Australian landscapes.

Many have histories associated with fire or some other disturbance. For example, a number of plants spend a significant part of their time as long-lived seeds – sometimes for decades – in the soil with nothing visible above ground, and with plants only appearing for a few years after a fire.

But by far, the greatest reason for the lack of information is the shortage of field surveys of the rare plants, and the availability of botanists and qualified biologists to survey suitable habitat and accurately identify the plants.

Purple-wood wattle (Acacia carneorum) is slow growing and rarely produces viable seed. Threats are not well understood but grazing by livestock and rabbits is likely to impact on the species.
Andrew Denham

What we’ve learnt

The continuing decline of Australia’s threatened plants suggests more extinctions are likely. But there have been important achievements and lessons learnt in dealing with the main causes of loss of native vegetation.

Our understanding of plant extinction processes – such as habitat loss, habitat degradation, invasive weeds, urbanisation, disease and climate change – is improving. But there is still a significant way to go.




Read more:
How I discovered the Dalveen Blue Box, a rare eucalypt species with a sweet, fruity smell


One challenge in dealing with the causes of Australian plant extinction is how to manage introduced diseases.

Two plant diseases in particular are of major concern: Phytophthora dieback, a soil-borne water mould pathogen, and Myrtle rust, which is spread naturally by wind and water.

Both diseases are increasingly recognised as threats, not only because of the impact they are already having on diverse native plant communities and many rare species, but also because of the difficulties in effective control.

Two Australian rainforest tree species Rhodomyrtus psidioides and Rhodamnia rubescens were recently listed as threatened under the NSW legislation because of myrtle rust.

Native guava (Rhodomyrtus psidioides) A tree species around the margins of rainforest between the NSW and the QLD border. The species is has now been listed as Critically Endangered. Surveys of rainforest areas infected with Myrtle Rust found that 50 to 95% of native guava trees were killed by the disease within a few years.
Zaareo/Wikimedia

While extinction associated with disease is often rapid, some individual plants may survive for decades in highly degraded landscapes, such as long-lived woody shrubs and trees. These plants will ultimately go extinct, and this is often difficult to communicate to the public.

While individual species will continue to persist for many years in highly disturbed and fragmented landscapes, there is little or no reproduction. And with their populations restricted to extremely small patches of bush, they’re vulnerable to ongoing degradation.




Read more:
How many species on Earth? Why that’s a simple question but hard to answer


In many such cases there is an “extinction debt”, where it may take decades for extinction to occur, depending on the longevity of the plants involved.

But it’s not all doom and gloom. A recent study found of the 418 threatened Australian plants showing ongoing decline, 83% were assessed as having medium to high potential for bouncing back.

And with long-term investment and research there are good prospects of saving the majority of these plants.The Conversation

David Coates, Adjunct Professor and Research Associate, University of Western Australia

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

Why climate change will dull autumn leaf displays



File 20190402 177178 1o0ksl1.jpg?ixlib=rb 1.1
Autumnal displays may be dimmed in the future.
Shutterstock

Matthew Brookhouse, Australian National University

Every autumn we are treated to one of nature’s finest seasonal annual transitions: leaf colour change and fall.

Most of the autumn leaf-shedding trees in Australia are not native, and some are declared weeds. Nevertheless, Australia has a spectacular display of trees, from the buttery tresses of Ginkgo biloba to the translucent oaks, elms and maples.

Autumn colour changes are celebrated worldwide and, when the time is right, autumn leaves reconnect us to nature, driving “leaf-peeping” tourist economies worldwide.

However, recent temperature trends and extremes have changed the growing conditions experienced by trees and are placing autumn displays, such as Canberra’s, at risk.

Autumn leaf colour changes and fall are affected by summer temperatures.
Shutterstock

This year, Canberra, like the rest of Australia, endured its hottest summer on record. In NSW and the ACT, the mean temperature in January was 6°C warmer than the long-term average. So far, autumn is following suit.

These extremes can interrupt the ideal synchronisation of seasonal changes in temperature and day length, subduing leaf colours.

In addition, hotter summer temperatures scorch leaves and, when combined with this and the previous years’ low autumn rainfall, cause trees to shed leaves prematurely, dulling their autumn leaf displays.




Read more:
Smart city planning can preserve old trees and the wildlife that needs them


The subtlety of change

We learnt in childhood autumn colour change follows the arrival of cooler temperatures. Later we learnt the specifics: seasonal changes in day length and temperature drive the depletion of green chlorophyll in leaves. Temperature can also affect the rate at which it fades.

In the absence of chlorophyll, yellows and oranges generated by antioxidants in the leaf (carotenoids) as well as red through to purples pigments (anthocyanins), synthesised from stored sugars, emerge. Temperature plays a role here too – intensifying colours as overnight temperatures fall.

We’ve also come to understand the role of a leaf’s environment. Anthocyanin production is affected by light intensity, which explains why sunny autumns produce such rich colours and why the canopies of our favourite trees blush red at their edges while glowing golden in their interior.

However, early signs show this year’s autumn tones will be muted. After the record-breaking heat of summer and prolonged heat of March, many trees are shrouded in scorched, faded canopies. The ground is littered with blackened leaves.

Of course, we’ve seen it before.

During the Millennium Drought, urban trees sporadically shed their leaves often without a hint of colour change. Fortunately, that was reversed at the drought’s end.

But we’re kidding ourselves if we believe this last summer was normal or recent temperature trends are just natural variability. If this is a sign of seasons future, we need to prepare to lose some of autumn’s beauty.




Read more:
Are more Aussie trees dying of drought? Scientists need your help spotting dead trees


Lost synchronicity

Long-term and experimental data show that the sensitivity of autumn colour change to warmer temperatures varies widely between species. While large-scale meta-analyses point to a delay in the arrival of autumn colours of one day per degree of warming, individual genera may be far more sensitve. Colour change in Fagus is delayed by 6-8 days per degree.

Warming temperatures, then, mean the cohesive leaf-colour changes we’re accustomed to will break down at landscape scales.

In addition, as warm weather extends the growing season and deep-rooted trees deplete soil moisture reservoirs, individual trees are driven by stress rather than seasonal temperature change and cut their losses. They shed leaves at the peripheries of their canopies.

The remainder wait – bronzed by summer, but still mostly green – for the right environmental cue.

For years, careful species selection and selective breeding enhanced autumn colour displays. This rich tapestry is now unravelling as hotter summers, longer autumns and drought affect each species differently.




Read more:
How tree bonds can help preserve the urban forest


Paradoxes and indirect effects

It seems logical warmer temperatures would mean shorter and less severe frost seasons. Paradoxically, observations suggest otherwise – the arrival of frost is unchanged or, worse, occurring earlier.

When not preceded by gradually cooling overnight temperatures, frosts can induce sudden, unceremonious leaf loss. If warm autumn temperatures fail to initiate colour change, autumn displays can be short-circuited entirely.

At the centre of many urban-tree plantings, our long association with elms faces a threat. Loved for the contrast their clear yellow seasonal display creates against pale autumn skies, elm canopies have been ravaged by leaf beetles this year. Stress has made trees susceptible to leaf-eating insects, and our current season delivered an expanse of stressed, and now skeletal, trees.

Autumn leaf displays drive tourism.
Norm Hanson/flickr, CC BY-NC-SA



Read more:
Where the old things are: Australia’s most ancient trees


Change everywhere?

This dulled image of autumn is far from universal. Climates differ between locations. So too will the climate changes we’ve engineered and their impact on autumn displays.

Increased concentration of anthocyanins associated with warmer summers has, for example, created spectacular leaf displays in Britain’s cooler climates.

Of course, we’ll continue to experience radiant autumn displays too.

In years of plentiful rain, our trees will retain their canopies and then, in the clear skies of autumn, dazzle us with seasonal celebrations. However, that too may be tempered by the increased risk of colour-sapping pathogens, such as poplar rust, favoured by warm, moist conditions. And there are also negative consequences for autumn colour associated with elevated carbon dioxide concentrations.

Of course, we need to keep it in perspective – the dulling of autumn’s luminescence is far from the worst climate change impacts. Nevetheless, in weakening our link with nature, the human psyche is suffering another self-inflicted cut as collective action on climate change stalls.The Conversation

Matthew Brookhouse, Senior lecturer, Australian National University

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

The 39 endangered species in Melbourne, Sydney, Adelaide and other Australian cities



File 20190402 177190 cksuwv.jpg?ixlib=rb 1.1
Threatened species live in cities and towns around Australia, including the critically endangered western swamp tortoise.
Elia Purtle, AAP Image/Perth Zoo

Kylie Soanes, University of Melbourne and Pia Lentini

The phrase “urban jungle” gets thrown around a lot, but we don’t usually think of cities as places where rare or threatened species live.

Our research, published today in Frontiers in Ecology and the Environment, shows some of Australia’s most endangered plants and animals live entirely within cities and towns.

Stuck in the city with you

Australia is home to 39 urban-restricted threatened species, from giant gum trees, to ornate orchids, wonderful wattles, and even a tortoise. Many of these species are critically endangered, right on the brink of extinction. And cities are our last chance to preserve them within their natural range.


Credit: Elia Purtle

Urban environments offer a golden opportunity to preserve species under threat and engage people with nature. But that means we might need to think a little differently about how and where we do conservation, embrace the weird and wonderful spaces that these species call home, and involve urban communities in the process.

Roads to the left of them, houses to the right

When you picture city animals you might think of pigeons, sparrows or rats that like to hang out with humans, or the flying foxes and parrots that are attracted to our flowering gardens.

But that’s not the case here. The threatened species identified in our research didn’t choose the city life, the city life chose them. They’re living where they’ve always lived. As urban areas expand, it just so happens that we now live there too.

The first hurdle that springs to mind when it comes to keeping nature in cities is space: there’s not a lot of it, and it’s quickly disappearing. For example, the magnificent Caley’s Grevillea has lost more than 85% of its habitat in Sydney to urban growth, and many of its remaining haunts are earmarked for future development. Around half of the urban-restricted species on our list are in the same predicament.

It’s especially tough to protect land for conservation in urban environments, where development potential means high competition for valuable land. So when protected land is a luxury that few species can afford, we need to work out other ways to look after species in the city.

Caley’s grevillea has lost 85% of its habitat as Sydney has expanded.
Isaac Mammott

Not living where you’d expect

Precious endangered species aren’t all tucked away in national parks and conservation reserves. These little battlers are more often found hiding in plain sight, amid the urban hustle and bustle.

Our research found them living along railway lines and roadsides, sewerage treatment plants and cemeteries, schools, airports, and even a hospital garden. While these aren’t the typical places you’d expect to find threatened species, they’re fantastic opportunities for conservation.

The spiked rice flower is a great example. Its largest population is on a golf course in New South Wales, where local managers work to enhance its habitat between the greens, and raise awareness among residents and local golfers. These kinds of good partnerships between local landowners and conservation can find “win-win” situations that benefit people and nature.




Read more:
Just ten MPs represent more than 600 threatened species in their electorates


A series of unfortunate events

It’s no secret that living in the ‘burbs can be risky: a fact best illustrated in the cautionary tale of a roadside population of the endangered Angus’s onion orchid. Construction workers once unwittingly dumped ten tonnes of sand over the patch in the late 1980s, then quickly attempted to fix the problem using a bulldozer and a high-pressure hose. Later, a portaloo was plonked on top of it.

Examples like this show just how important it is for policy makers, land managers and the community to know that these species are there in the first place, and are aware that even scrappy-looking habitats can be important to their survival. Otherwise, species are just one stroke of bad luck away from extinction.

People power

It’s common to think if you want to conserve nature, you need to get as far away from people as you can. After all, we can be a dangerous lot (just ask Angus’s onion orchid). But we also have extraordinary potential to create positive change – and it’s much easier for us to do this if we only have to travel as far as our backyard or a local park.

Many urban-restricted species get support by their local communities. Examples from our research showed communities across Melbourne raising thousands of dollars in conservation crowdfunding, dedicating countless volunteer hours to caring for local habitats, and even setting up neighbourhood watches to combat vandals. This shows a huge opportunity for urban residents to be on the conservation frontline.

Our research focused on 39 species that are restricted to Australian cities and towns today. But that’s not where the opportunity for urban conservation ends.

There are about another 370 threatened species that share their range with urban areas across Australia, as well as countless “common” native species that call cities home. And as cities continue to expand, many other threatened species stand to become urban dwellers. It’s clear that if we only focus conservation efforts in areas far from humans, species like these will be lost forever.The Conversation

Kylie Soanes, Postdoctoral fellow, University of Melbourne and Pia Lentini, Research Fellow, The University of Melbourne

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

Are more Aussie trees dying of drought? Scientists need your help spotting dead trees



File 20190326 36273 5tp4r3.jpg?ixlib=rb 1.1
As climate change threatens Australian trees, it’s important to identify which are at risk.
Nicolás Boullosa/flickr, CC BY-SA

Belinda Medlyn, Western Sydney University; Brendan Choat, Western Sydney University, and Martin De Kauwe, UNSW

Most citizen science initiatives ask people to record living things, like frogs, wombats, or feral animals. But dead things can also be hugely informative for science. We have just launched a new citizen science project, The Dead Tree Detective, which aims to record where and when trees have died in Australia.

The current drought across southeastern Australia has been so severe that native trees have begun to perish, and we need people to send in photographs tracking what has died. These records will be valuable for scientists trying to understand and predict how native forests and woodlands are vulnerable to climate extremes.




Read more:
Recent Australian droughts may be the worst in 800 years


Understanding where trees are most at risk is becoming urgent because it’s increasingly clear that climate change is already underway. On average, temperatures across Australia have risen more than 1℃ since 1910, and winter rainfall in southern Australia has declined. Further increases in temperature, and increasing time spent in drought, are forecast.

How our native plants cope with these changes will affect (among other things) biodiversity, water supplies, fire risk, and carbon storage. Unfortunately, how climate change is likely to affect Australian vegetation is a complex problem, and one we don’t yet have a good handle on.

Phil Spark of Woolomin, NSW submitted this photo to The Dead Tree Detective project online.
Author provided

Climate niche

All plants have a preferred average climate where they grow best (their “climatic niche”). Many Australian tree species have small climatic niches.

It’s been estimated an increase of 2℃ would see 40% of eucalypt species stranded in climate conditions to which they are not adapted.

But what happens if species move out of their climatic niche? It’s possible there will be a gradual migration across the landscape as plants move to keep up with the climate.




Read more:
How the warming world could turn many plants and animals into climate refugees


It’s also possible that plants will generally grow better, if carbon dioxide rises and frosts become less common (although this is a complicated and disputed claim.

Farmers have reported anecdotal evidence of tree deaths on social media.
Author provided

However, a third possibility is that increasing climate extremes will lead to mass tree deaths, with severe consequences.

There are examples of all three possibilities in the scientific literature, but reports of widespread tree death are becoming increasingly commonplace.

Many scientists, including ourselves, are now trying to identify the circumstances under which we may see trees die from climate stress. Quantifying these thresholds is going to be key for working out where vegetation may be headed.

The water transport system

Australian plants must deal with the most variable rainfall in the world. Only trees adapted to prolonged drought can survive. However, drought severity is forecast to increase, and rising heat extremes will exacerbate drought stress past their tolerance.

To explain why droughts overwhelm trees, we need to look at the water transport system that keeps them alive. Essentially, trees draw water from the soil through their roots and up to their leaves. Plants do not have a pump (like our hearts) to move water – instead, water is pulled up under tension using energy from sunlight. Our research illustrates how this transport system breaks down during droughts.

Lyn Lacey submitted these photos of dead trees at Ashford, NSW to The Dead Tree Detective.
Author provided

In hot weather, more moisture evaporates from trees’ leaves, putting more pressure on their water transport system. This evaporation can actually be useful, because it keeps the trees’ leaves cool during heatwaves. However if there is not enough water available, leaf temperatures can become lethally high, scorching the tree canopy.

We’ve also identified how drought tolerance varies among native tree species. Species growing in low-rainfall areas are better equipped to handle drought, showing they are finely tuned to their climate niche and suggesting many species will be vulnerable if climate change increases drought severity.

Based on all of these data, we hope to be able to predict where and when trees will be vulnerable to death from drought and heat stress. The problem lies in testing our predictions – and that’s where citizen science comes in. Satellite remote sensing can help us track overall greenness of ecosystems, but it can’t detect individual tree death. Observation on the ground is needed.

These images show a failure of the water transport system in Eucalyptus saligna. Left: well-watered plant. Right: severely droughted plant. On the right, air bubbles blocking the transport system can be seen.
Brendan Choat, Author provided

However, there is no system in place to record tree death from drought in Australia. For example, during the Millennium Drought, the most severe and extended drought for a century in southern Australia, there are almost no records of native tree death (other than along the rivers, where over-extraction of water was also an issue). Were there no deaths? Or were they simply not recorded?

The current drought gripping the southeast has not been as long as the Millennium Drought, but it does appear to be more intense, with some places receiving almost no rain for two years. We’ve also had a summer of repeated heatwaves, which will have intensified the stress.




Read more:
Is Australia’s current drought caused by climate change? It’s complicated


We’re hearing anecdotal reports of tree death in the news and on twitter. We’re aiming to capture these anecdotal reports, and back them up with information including photographs, locations, numbers and species of trees affected, on the Dead Tree Detective.

We encourage anyone who sees dead trees around them to hop online and contribute. The Detective also allows people to record tree deaths from other causes – and trees that have come back to life again (sometimes dead isn’t dead). It can be depressing to see trees die – but recording their deaths for science helps to ensure they won’t have died in vain.The Conversation

Belinda Medlyn, Professor, Western Sydney University; Brendan Choat, Associate Professor, Western Sydney University, and Martin De Kauwe, Senior Research Fellow, UNSW

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

An end to endings: how to stop more Australian species going extinct



File 20190305 48435 o1z6b8.jpg?ixlib=rb 1.1

John Gerrard Keulemans. Published by Muséum national d’histoire naturelle (France)

John Woinarski, Charles Darwin University; Sarah Legge, Australian National University, and Stephen Garnett, Charles Darwin University

This is part of a major series called Advancing Australia, in which leading academics examine the key issues facing Australia in the lead-up to the 2019 federal election and beyond. Read the other pieces in the series here.


We need nature. It gives us inspiration, health, resources, life. But we are losing it. Extinction is the most acute and irreversible manifestation of this loss.

Australian species have suffered at a disproportionate rate. Far more mammal species have become extinct in Australia than in any other country over the past 200 years.

The thylacine is the most recognised and mourned of our lost species, but the lesser bilby has gone, so too the pig-footed bandicoot, the Toolache wallaby, the white-footed rabbit-rat, along with many other mammals that lived only in Australia. The paradise parrot has joined them, the robust white-eye, the King Island emu, the Christmas Island forest skink, the southern gastric-brooding frog, the Phillip Island glory pea, and at least another 100 species that were part of the fabric of this land, part of what made Australia distinctive.

And that’s just the tally for known extinctions. Many more have been lost without ever being named. Still others hover in the graveyard – we’re not sure whether they linger or are gone.




Read more:
What makes some species more likely to go extinct?


The losses continue: three Australian vertebrate species became extinct in the past decade. Most of the factors that caused the losses remain unchecked, and new threats are appearing, intensifying, expanding. Many species persist only in slivers of their former range and in a fraction of their previous abundance, and the long-established momentum of their decline will soon take them over the brink.

The toolache wallaby is just one of Australia’s many extinct species.
John Gould, F.R.S., Mammals of Australia, Vol. II Plate 19, London, 1863

Unnecessarily extinct

These losses need not have happened. Almost all were predictable and preventable. They represent failures in our duty of care, legislation, policy and management. They give witness to, and warn us about, the malaise of our land and waters.

How do we staunch the wound and maintain Australia’s wildlife? It’s a problem with many facets and no single solution. Here we provide ten recommendations, based on an underlying recognition that more extinctions will be inevitable unless we treat nature as part of the essence of this country, rather than as a dispensable tangent, an economic externality.

  1. We should commit to preventing any more extinctions. As a society, we need to treat our nature with more respect – our plants and animals have lived in this place for hundreds of thousands, often millions, of years. They are integral to this country. We should not deny them their existence.

  2. We should craft an intergenerational social contract. We have been gifted an extraordinary nature. We have an obligation to pass to following generations a world as full of wonder, beauty and diversity as our generation has inherited.

  3. We should highlight our respect for, and obligation to, nature in our constitution, just as that fusty document could be refreshed and some of its deficiencies redressed through the Uluru Statement from the Heart. Those drafting the blueprint for the way our country is governed gave little or no heed to its nature. A constitution is more than a simple administrative rule book. Countries such as Ecuador, Palau and Bhutan have constitutions that commit to caring for their natural legacy and recognise that society and nature are interdependent.

  4. We should build a generation-scale funding commitment and long-term vision to escape the fickle, futile, three-year cycle of contested government funding. Environmental challenges in Australia are deeply ingrained and longstanding, and the conservation response and its resourcing need to be implemented on a scale of decades.

  5. As Paul Keating stated in his landmark Redfern speech, we should all see Australia through Aboriginal eyes – more deeply feel the way the country’s heart beats; become part of the land; fit into the landscape. This can happen through teaching curricula, through reverting to Indigenous names for landmarks, through reinvigorating Indigenous land management, and through pervasive cultural respect.

  6. We need to live within our environmental limits – constraining the use of water, soil and other natural resources to levels that are sustainable, restraining population growth and setting a positive example to the world in our efforts to minimise climate change.

  7. We need to celebrate and learn from our successes. There are now many examples of how good management and investments can help threatened species recover. We are capable of reversing our mismanagement.

  8. Funding to prevent extinctions is woefully inadequate, of course, and needs to be increased. The budgeting is opaque, but the Australian government spends about A$200 million a year on the conservation of threatened species, about 10% of what the US government outlays for its own threatened species. Understandably, our American counterparts are more successful. For context, Australians spend about A$4 billion a year caring for pet cats.

  9. Environmental law needs strengthening. Too much is discretionary and enforcement is patchy. We suggest tightening the accountability for environmental failures, including extinction. Should species die out, formal inquests should be mandatory to learn the necessary lessons and make systemic improvements.

  10. We need to enhance our environmental research, management and monitoring capability. Many threatened species remain poorly known and most are not adequately monitored. This makes it is hard to measure progress in response to management, or the speed of their collapse towards extinction.




Read more:
Eulogy for a seastar, Australia’s first recorded marine extinction


Extinction is not inevitable. It is a failure, potentially even a crime – a theft from the future that is entirely preventable. We can and should prevent extinctions, and safeguard and celebrate the diversity of Australian life.The Conversation

John Woinarski, Professor (conservation biology), Charles Darwin University; Sarah Legge, Professor, Australian National University, and Stephen Garnett, Professor of Conservation and Sustainable Livelihoods, Charles Darwin University

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