Joshua Powell, UCLThe return of wolves to Yellowstone National Park in 1995 popularised the idea of reintroducing long-lost species to modern habitats. While scientists are still trying to fully understand the ecological consequences, the wolf’s reintroduction likely benefited other species, illustrating how conservation can not just slow biodiversity loss, but even reverse it.
That project, however, took place in a vast protected wilderness. Many of the places where biologists now hope to reintroduce large wild animals – whether it’s lynx in Britain or cheetahs in India – are a little closer to where people live, with all of the potential problems that entails in terms of human-wildlife conflict.
In South Korea, a country of similar size and similar human population density to England, conservationists are in the process of restoring the native bear population, Asiatic black bears, or moon bears, to be precise. While slightly smaller than their North American cousins, these are still large wild animals, capable of causing fear and alarm and posing a risk to human life and property.
I wanted to find out how South Korea is managing this ambitious project, so I travelled to Jirisan National Park, a mountainous region in the far south of the Korean Peninsula.
By the 1990s, along with occasional sightings in the Demilitarised Zone (DMZ), Jirisan had become the last foothold of the Asiatic black bear in South Korea. An attempted eradication programme by the colonial Japanese regime of the early 20th century and overhunting following independence in 1945 meant bears had fared badly for some time. At the close of the century, there were thought to be just five wild bears left in the country, and the species was on the brink of extinction in South Korea.
These were not the only bears in the country though. A large population lingered on farms producing bear bile and body parts, which are used in traditional medicine, and bear meat. Since the 1990s, South Korea has cracked down on the bear part trade, but the remaining population of around 380 captive bears still substantially outnumbers those in the wild (around 70 in 2021).
These farm bears might have seemed the ideal animals to rebuild a wild population. But the bears probably belonged to a range of different subspecies and were potential disease risks. Years of being fed by humans also meant that the bears could seek out contact – and cause conflict – with humans. Instead, bears were imported from China, Russia and North Korea. In 2004, the first six cubs were released into Jirisan.
Why did South Korea’s bear programme succeed?
No grand claims were made about reshaping the relationship between humans and the natural world, and no changes were promised to centuries-old methods of managing landscapes, ideas which often feature in debates about rewilding. Instead, conservationists in South Korea established a modest initial goal: returning a population of 50 bears to a single protected area.
Soft releases, in which bears are kept in pens to acclimate to their surroundings before being set free, and extensive monitoring of bears post-release, helped increase the likelihood of each released bear surviving. Bears that strayed too far were returned to the national park.
Captive breeding, underpinned by impressive veterinary expertise, has also helped the population grow. One milestone involved the world’s first successful use of artificial insemination in this genus of bear, a boon for maintaining genetic diversity in a small population. Bears injured by snares or traffic collisions have also been successfully returned to the wild.
The initial target of 50 bears was exceeded and the population now stands at over 70. A recent study found that some bears were now dispersing across South Korea, suggesting that Jirisan National Park may be close to reaching the limit of bears it can sustain.
This presents new challenges. Conservationists have, so far, been remarkably successful at reducing conflict between bears and people, and building support for restoring bears to Jirisan National Park with education programmes, presentations for residents and hikers, a centre where visitors can learn about the reintroduction programme and even the use of moon bear mascots for the 2018 Pyeongchang Winter Paralympics.
But the appearance of bears outside of the national park still attracts prime-time media coverage, which can hamper efforts to cultivate tolerance and maintain a reasonable dialogue with the public about the realities of living alongside bears. People feeding bears remains an issue, as does illegal snaring for game species, which can severely injure bears. As South Korea reaches the next stage of its reintroduction programme, is the country prepared to accept bears outside of a protected area?
It will be fascinating to follow these bears over the coming years as conservationists address these questions. And Asiatic black bears are just the start. South Korea has since established programmes to restore the red fox, which is surprisingly rare in the country, and the long-tailed goral, a goat-like mammal whose populations have been depleted by poaching and habitat loss.
These programmes will face challenges, but South Korea has shown considerable expertise in the field of mammal reintroductions. Expertise that other countries could well learn from.
Nicky Wright, University of Sydney; Andréa S. Taschetto, UNSW, and Andrew King, The University of MelbourneThis month we’ve seen some crazy, devastating weather. Perth recorded its wettest July in decades, with 18 straight days of relentless rain. Overseas, parts of Europe and China have endured extensive flooding, with hundreds of lives lost and hundreds of thousands of people evacuated.
And last week, Australia’s Bureau of Meteorology officially declared there is a negative Indian Ocean Dipole — the first negative event in five years — known for bringing wet weather.
But what even is the Indian Ocean Dipole, and does it matter? Is it to blame for these events?
What is the Indian Ocean Dipole?
The Indian Ocean Dipole, or IOD, is a natural climate phenomenon that influences rainfall patterns around the Indian Ocean, including Australia. It’s brought about by the interactions between the currents along the sea surface and atmospheric circulation.
It can be thought of as the Indian Ocean’s cousin of the better known El Niño and La Niña in the Pacific. Essentially, for most of Australia, El Niño brings dry weather, while La Niña brings wet weather. The IOD has the same impact through its positive and negative phases, respectively.
Positive IODs are associated with an increased chance for dry weather in southern and southeast Australia. The devastating Black Summer bushfires in 2019–20 were linked to an extreme positive IOD, as well as human-caused climate change which exacerbated these conditions.
Negative IODs tend to be less frequent and not as strong as positive IOD events, but can still bring severe climate conditions, such as heavy rainfall and flooding, to parts of Australia.
The IOD is determined by the differences in sea surface temperature on either side of the Indian Ocean.
During a negative phase, waters in the eastern Indian Ocean (near Indonesia) are warmer than normal, and the western Indian Ocean (near Africa) are cooler than normal.
Explainer: El Niño and La Niña
This causes more moisture-filled air to flow towards Australia, favouring wind pattern changes in a way that promotes more rainfall to southern parts of Australia. This includes parts of Western Australia, South Australia, Victoria, NSW and the ACT.
Generally, IOD events start in late autumn or winter, and can last until the end of spring — abruptly ending with the onset of the northern Australian monsoon.
Why should we care?
We probably have a wet few months ahead of us.
The negative IOD means the southern regions of Australia are likely to have a wet winter and spring. Indeed, the seasonal outlook indicates above average rainfall for much of the country in the next three months.
In southern Australia, a negative IOD also means we’re more likely to get cooler daytime temperatures and warmer nights. But just because we’re more likely to have a wetter few months doesn’t mean we necessarily will — every negative IOD event is different.
While the prospect of even more rain might dampen some spirits, there are reasons to be happy about this.
First of all, winter rainfall is typically good for farmers growing crops such as grain, and previous negative IOD years have come with record-breaking crop production.
Negative IOD years can also bring better snow seasons for Australians. However, the warming trend from human-caused climate change means this signal isn’t as clear as it was in the past.
It’s not all good news
This is the first official negative IOD event since 2016, a year that saw one of the strongest negative IOD events on record. It resulted in Australia’s second wettest winter on record and flooding in parts of NSW, Victoria, and South Australia.
Thankfully, current forecasts indicate the negative IOD will be a little milder this time, so we hopefully won’t see any devastating events.
Is the negative IOD behind the recent wet weather?
It’s too early to tell, but most likely not.
Negative IODs tend to be associated with moist air flow and lower atmospheric pressure further north and east than Perth, such as Geraldton to Port Hedland.
Outside of Australia, there has been extensive flooding in China and across Germany, Belgium, and The Netherlands.
It’s still early days and more research is needed, but these events look like they might be linked to the Northern Hemisphere’s atmospheric jet stream, rather than the negative IOD.
The jet stream is like a narrow river of strong winds high up in the atmosphere, formed when cool and hot air meet. Changes in this jet stream can lead to extreme weather.
What about climate change?
The IOD — as well as El Niño and La Niña — are natural climate phenomena, and have been occurring for thousands of years, before humans started burning fossil fuels. But that doesn’t mean climate change today isn’t having an effect on the IOD.
Scientific research is showing positive IODs — linked to drier conditions in eastern Australia — have become more common. And this is linked to human-caused climate change influencing ocean temperatures.
Climate models also suggest we may experience more positive IOD events in future, including increased chances of bushfires and drought in Australia, and fewer negative IOD events. This may mean we experience more droughts and less “drought-breaking” rains, but the jury’s still out.
When it comes to the recent, devastating floods overseas, scientists are still assessing how much of a role climate change played.
But in any case, we do know one thing for sure: rising global temperatures from climate change will cause more frequent and severe extreme events, including the short-duration heavy rainfalls associated with flooding, and heatwaves.
To avoid worse disasters in our future, we need to cut emissions drastically and urgently.
Jodi Rowley, Australian Museum and Karrie Rose, University of SydneyOver the past few weeks, we’ve received a flurry of emails from concerned people who’ve seen sick and dead frogs across eastern Victoria, New South Wales and Queensland.
One person wrote:
About a month ago, I noticed the Green Tree Frogs living around our home showing signs of lethargy & ill health. I was devastated to find about 7 of them dead.
We previously had a very healthy population of green tree frogs and a couple of months ago I noticed a frog that had turned brown. I then noticed more of them and have found numerous dead frogs around our property.
And another said she’d seen so many dead frogs on her daily runs she had to “seriously wonder how many more are there”.
So what’s going on? The short answer is: we don’t really know. How many frogs have died and why is a mystery, and we’re relying on people across Australia to help us solve it.
Why are frogs important?
Frogs are an integral part of healthy Australian ecosystems. While they are usually small and unseen, they’re an important thread in the food web, and a kind of environmental glue that keeps ecosystems functioning. Healthy frog populations are usually a good indication of a healthy environment.
They eat vast amounts of invertebrates, including pest species, and they’re a fundamental food source for a wide variety of other wildlife, including birds, mammals and reptiles. Tadpoles fill our creeks and dams, helping keep algae and mosquito larvae under control while they too become food for fish and other wildlife.
But many of Australia’s frog populations are imperilled from multiple, compounding threats, such as habitat loss and modification, climate change, invasive plants, animals and diseases.
Although we’re fortunate to have at least 242 native frog species in Australia, 35 are considered threatened with extinction. At least four are considered extinct: the southern and northern gastric-brooding frogs (Rheobatrachus silus and Rheobatrachus vitellinus), the sharp-snouted day frog (Taudactylus acutirostris) and the southern day frog (Taudactylus diurnus).
A truly unusual outbreak
In most circumstances, it’s rare to see a dead frog. Most frogs are secretive in nature and, when they die, they decompose rapidly. So the growing reports of dead and dying frogs from across eastern Australia over the last few months are surprising, to say the least.
While the first cold snap of each year can be accompanied by a few localised frog deaths, this outbreak has affected more animals over a greater range than previously encountered.
This is truly an unusual amphibian mass mortality event.
In this outbreak, frogs appear to be either darker or lighter than normal, slow, out in the daytime (they’re usually nocturnal), and are thin. Some frogs have red bellies, red feet, and excessive sloughed skin.
The iconic green tree frog (Litoria caeulea) seems hardest hit in this event, with the often apple-green and plump frogs turning brown and shrivelled.
This frog is widespread and generally rather common. In fact, it’s the ninth most commonly recorded frog in the national citizen science project, FrogID. But it has disappeared from parts of its former range.
Other species reported as being among the sick and dying include Peron’s tree frog (Litoria peronii), the Stony Creek frog (Litoria lesueuri), and green stream frog (Litoria phyllochroa). These are all relatively common and widespread species, which is likely why they have been found in and around our gardens.
We simply don’t know the true impacts of this event on Australia’s frog species, particularly those that are rare, cryptic or living in remote places. Well over 100 species of frog live within the geographic range of this outbreak. Dozens of these are considered threatened, including the booroolong Frog (Litoria booroolongensis) and the giant barred frog (Mixophyes iteratus).
So what might be going on?
Amphibians are susceptible to environmental toxins and a wide range of parasitic, bacterial, viral and fungal pathogens. Frogs globally have been battling it out with a pandemic of their own for decades — a potentially deadly fungus often called amphibian chytrid fungus.
This fungus attacks the skin, which frogs use to breathe, drink, and control electrolytes important for the heart to function. It’s also responsible for causing population declines in more than 500 amphibian species around the world, and 50 extinctions.
For example, in Australia the bright yellow and black southern corroboree frog (Pseudophryne corroboree) is just hanging on in the wild, thanks only to intensive management and captive breeding.
Curiously, some other frog species appear more tolerant to the amphibian chytrid fungus than others. Many now common frogs seem able to live with the fungus, such as the near-ubiquitous Australian common eastern froglet (Crinia signifera).
But if frogs have had this fungus affecting them for decades, why are we seeing so many dead frogs now?
Well, disease is the outcome of a battle between a pathogen (in this case a fungus), a host (in this case the frog) and the environment. The fungus doesn’t do well in warm, dry conditions. So during summer, frogs are more likely to have the upper hand.
In winter, the tables turn. As the frog’s immune system slows, the fungus may be able to take hold.
Of course, the amphibian chytrid fungus is just one possible culprit. Other less well-known diseases affect frogs.
To date, the Australian Registry of Wildlife Health has confirmed the presence of the amphibian chytrid fungus in a very small number of sick frogs they’ve examined from the recent outbreak. However, other diseases — such as ranavirus, myxosporean parasites and trypanosome parasites — have also been responsible for native frog mass mortality events in Australia.
It’s also possible a novel or exotic pathogen could be behind this. So the Australian Registry of Wildlife Health is working with the Australian Museum, government biosecurity and environment agencies as part of the investigation.
Here’s how you can help
While we suspect a combination of the amphibian chytrid fungus and the chilly temperatures, we simply don’t know what factors may be contributing to the outbreak.
We also aren’t sure how widespread it is, what impact it will have on our frog populations, or how long it will last.
While the temperatures stay low, we suspect our frogs will continue to succumb. If we don’t investigate quickly, we will lose the opportunity to achieve a diagnosis and understand what has transpired.
We need your help to solve this mystery.
Jodi Rowley, Curator, Amphibian & Reptile Conservation Biology, UNSW, Australian Museum and Karrie Rose, Australian Registry of Wildlife Health – Taronga Conservation Society Australia, University of Sydney
Neal Hughes, Australian Bureau of Agricultural and Resource Economics and Sciences (ABARES)Australian farmers have proven their resilience, rebounding from drought and withstanding a global pandemic to produce record-breaking output in 2020-21.
But while the pain of drought is fading from view for some, the challenge of a changing climate continues to loom large.
Farmers have endured a poor run of conditions over the last 20 years, including a reduction in average rainfall (particularly in southern Australia during the winter cropping season) and general increases in temperature.
While these trends relate to climate change, uncertainty remains over how they will develop, particularly over how much rain or drought farmers will face.
Research published today by the Australian Bureau of Agricultural and Resource Economics and Sciences (ABARES) examines the effects of past and potential future changes in climate, and sets out how productivity gains to date have been helping farmers adapt to the drier and hotter conditions.
Conditions have been tough
The research examines the effect on farms of climate conditions over the past 20 years, compared to the preceding 50 years.
Holding other factors constant (including commodity prices and technology) ABARES estimates the post-2000 shift in conditions reduced farm profits by an average of 23%, or around A$29,000 per farm per year.
As with past research, these effects have been strongest among cropping farmers in south-eastern and southern-western Australia, with impacts of over 50% observed in some of the most severely affected areas.
Effect of 2001 to 2020 climate conditions on average farm profit
Farmers have been adapting
While these changes in conditions have been dramatic, farmers’ adaptation has been equally impressive.
After controlling for climate, farm productivity (the output from a given amount of land and other inputs) has climbed around 28% since 1989, with a much larger 68% gain in the cropping sector.
These gains have offset the adverse climate conditions and along with increases in commodity prices have allowed farmers to maintain and even increase average production and profit levels over the last decade.
While productivity growth in agriculture is nothing new, the recent gains have been especially focused on adapting to drier and hotter conditions.
Within the cropping sector, for example, a range of new technologies and practices have emerged to better utilise soil moisture to cope with lower rainfall.
As a result, Australian farmers have produced remarkable harvests making use of limited rain, particularly in Western Australia.
Climate change could make conditions tougher
While climate models generally project a hotter and drier future, a wide range of outcomes are possible, particularly for rainfall.
Climate projections suggest that nationally farmers could experience reductions in average winter season rainfall of 3% to 30% by 2050 (compared to 1950-2000).
The study simulates the effect of future climate change scenarios with current farm technology and no further productivity gains.
As such, these scenarios are not a prediction, but an indication of which regions and sectors might be under the greatest pressure to adapt.
For example, under most scenarios cropping farmers in Western Australia will face more pressure than those in eastern Australia.
Livestock farms will also face more pressure under high emissions scenarios as they are especially impacted by higher temperatures.
Generally, inland low-rainfall farming areas are expected to face greater challenges than regions closer to the coast.
Simulated change in farm profits relative to historical (1950 to 2000) climate
There is more work ahead
Recent experience shows that productivity growth can help offset the impact of a changing climate.
However, there remains uncertainty over how far technology can push farm efficiency beyond current levels.
Further, even if technology can offset climate impacts, other exporting nations could still become more competitive relative to Australia, if they are less affected by climate change or can adapt faster.
Here, investment in research and development remains crucial, including efforts to improve the productivity and reduce the carbon footprint of existing crop and livestock systems, along with research into more transformational responses to help diversify farm incomes.
This could include for example, carbon and biodiversity farming, plantation forestry and the use of land to produce renewable energy.
Uncertainty over the future climate, especially rainfall, remains a key constraint on adaptation. Efforts to refine and better communicate climate information through initiatives such as Climate Services for Agriculture could help farmers and governments make more informed decisions.
While the future is still highly uncertain, the challenge of adapting to climate change is here and now.
Significant resources have been committed in this area, including the Australian government’s Future Drought Fund.
We need to make the most of these investments to prepare for whatever the future holds.
Thomas Newsome, University of Sydney; Christopher Wolf, Oregon State University, and William Ripple, Oregon State UniversityBack in 2019, more than 11,000 scientists declared a global climate emergency. They established a comprehensive set of vital signs that impact or reflect the planet’s health, such as forest loss, fossil fuel subsidies, glacier thickness, ocean acidity and surface temperature.
In a new paper published today, we show how these vital signs have changed since the original publication, including through the COVID-19 pandemic. In general, while we’ve seen lots of positive talk and commitments from some governments, our vital signs are mostly not trending in the right direction.
So, let’s look at how things have progressed since 2019, from the growing number of livestock to the meagre influence of the pandemic.
Is it all bad news?
No, thankfully. Fossil fuel divestment and fossil fuel subsidies have improved in record-setting ways, potentially signalling an economic shift to a renewable energy future.
However, most of the other vital signs reflect the consequences of the so far unrelenting “business as usual” approach to climate change policy worldwide.
Especially troubling is the unprecedented surge in climate-related disasters since 2019. This includes devastating flash floods in the South Kalimantan province of Indonesia, record heatwaves in the southwestern United States, extraordinary storms in India and, of course, the 2019-2020 megafires in Australia.
In addition, three main greenhouse gases — carbon dioxide, methane and nitrous oxide — set records for atmospheric concentrations in 2020 and again in 2021. In April this year, carbon dioxide concentration reached 416 parts per million, the highest monthly global average concentration ever recorded.
Last year was also the second hottest year in recorded history, with the five hottest years on record all occurring since 2015.
Ruminant livestock — cattle, buffalo, sheep, and goats — now number more than 4 billion, and their total mass is more than that of all humans and wild mammals combined. This is a problem because these animals are responsible for impacting biodiversity, releasing huge amounts of methane emissions, and land continues to be cleared to make room for them.
In better news, recent per capita meat production declined by about 5.7% (2.9 kilograms per person) between 2018 and 2020. But this is likely because of an outbreak of African swine fever in China that reduced the pork supply, and possibly also as one of the impacts of the pandemic.
Tragically, Brazilian Amazon annual forest loss rates increased in both 2019 and 2020. It reached a 12-year high of 1.11 million hectares deforested in 2020.
Ocean acidification is also near an all-time record. Together with heat stress from warming waters, acidification threatens the coral reefs that more than half a billion people depend on for food, tourism dollars and storm surge protection.
What about the pandemic?
With its myriad economic interruptions, the COVID-19 pandemic had the side effect of providing some climate relief, but only of the ephemeral variety.
But all of these are expected to significantly rise as the economy reopens. While global gross domestic product dropped by 3.6% in 2020, it is projected to rebound to an all-time high.
So, a major lesson of the pandemic is that even when fossil-fuel consumption and transportation sharply decrease, it’s still insufficient to tackle climate change.
There is growing evidence we’re getting close to or have already gone beyond tipping points associated with important parts of the Earth system, including warm-water coral reefs, the Amazon rainforest and the West Antarctic and Greenland ice sheets.
OK, so what do we do about it?
In our 2019 paper, we urged six critical and interrelated steps governments — and the rest of humanity — can take to lessen the worst effects of climate change:
- prioritise energy efficiency, and replace fossil fuels with low-carbon renewable energy
- reduce emissions of short-lived pollutants such as methane and soot
- curb land clearing to protect and restore the Earth’s ecosystems
- reduce our meat consumption
- move away from unsustainable ideas of ever-increasing economic and resource consumption
- stabilise and, ideally, gradually reduce human populations while improving human well-being especially by educating girls and women globally.
These solutions still apply. But in our updated 2021 paper, we go further, highlighting the potential for a three-pronged approach for near-term policy:
- a globally implemented carbon price
- a phase-out and eventual ban of fossil fuels
- strategic environmental reserves to safeguard and restore natural carbon sinks and biodiversity.
A global price for carbon needs to be high enough to induce decarbonisation across industry.
And our suggestion to create strategic environmental reserves, such as forests and wetlands, reflects the need to stop treating the climate emergency as a stand-alone issue.
By stopping the unsustainable exploitation of natural habitats through, for example, creeping urbanisation, and land degradation for mining, agriculture and forestry, we can reduce animal-borne disease risks, protect carbon stocks and conserve biodiversity — all at the same time.
Is this actually possible?
Yes, and many opportunities still exist to shift pandemic-related financial support measures into climate friendly activities. Currently, only 17% of such funds had been allocated that way worldwide, as of early March 2021. This percentage could be lifted with serious coordinated, global commitment.
Greening the economy could also address the longer term need for major transformative change to reduce emissions and, more broadly, the over-exploitation of the planet.
Our planetary vital signs make it clear we need urgent action to address climate change. With new commitments getting made by governments all over the world, we hope to see the curves in our graphs changing in the right directions soon.
Thomas Newsome, Academic Fellow, University of Sydney; Christopher Wolf, Postdoctoral Scholar, Oregon State University, and William Ripple, Distinguished Professor and Director, Trophic Cascades Program, Oregon State University
Darcy Watchorn, Deakin University; Dale Nimmo, Charles Sturt University; Mitchell Cowan, Charles Sturt University, and Tim Doherty, University of SydneyWildlife worldwide is facing a housing crisis. When land is cleared for agriculture, mining, and urbanisation, habitats and natural refuges go with it, such as tree hollows, rock piles and large logs.
The ideal solution is to tackle the threats that cause habitat loss. But some refuges take hundreds of years to recover once destroyed, and some may never recover without help. Tree hollows, for example, can take 180 years to develop.
As a result, conservationists have increasingly looked to human-made solutions as a stopgap. That’s where artificial refuges come in.
If the goal of artificial refuges is to replace lost or degraded habitat, then it is important we have a good understanding of how well they perform. Our new research reviewed artificial refuges worldwide — and we found the science underpinning them is often not up to scratch.
What are artificial refuges?
Artificial refuges provide wildlife places to shelter, breed, hibernate, or nest, helping them survive in disturbed environments, whether degraded forests, deserts or urban and agricultural landscapes.
You’re probably already familiar with some. Nest boxes for birds and mammals are one example found in many urban and rural areas. They provide a substitute for tree hollows when land is cleared.
Other examples include artificial stone cavities used in Norway to provide places for newts to hibernate in urban and agricultural environments, and artificial bark used in the USA to allow bats to roost in the absence of trees. And in France, artificial burrows provide refuge for lizards in lieu of their favoured rabbit burrows.
But do we know if they work?
Artificial refuges can be highly effective. In central Europe, for example, nest boxes allowed isolated populations of a colourful bird, the hoopoe, to reconnect — boosting the local genetic diversity.
Still, they are far from a sure thing, having at times fallen short of their promise to provide suitable homes for wildlife.
One study from Catalonia found 42 soprano pipistrelles (a type of bat) had died from dehydration within wooden bat boxes, due to a lack of ventilation and high sun exposure.
Another study from Australia found artificial burrows for the endangered pygmy blue tongue lizard had a design flaw that forced lizards to enter backwards. This increased their risk of predation from snakes and birds.
And the video below from Czech conservation project Birds Online shows a pine marten (a forest-dwelling mammal) and tree sparrow infiltrating next boxes to steal the eggs of Tengmalm’s owls and common starlings.
So why is this happening?
Our research investigated the state of the science regarding artificial refuges worldwide.
We looked at more than 220 studies, and we found they often lacked the rigour to justify their widespread use as a conservation tool. Important factors were often overlooked, such as how temperatures inside artifical refuges compare to natural refuges, and the local abundance of food or predators.
Alarmingly, just under 40% of studies compared artificial refuges to a control, making it impossible to determine the impacts artificial refuges have on the target species, positive or negative.
This is a big problem, because artificial refuges are increasingly incorporated into programs that seek to “offset” habitat destruction. Offsetting involves protecting or creating habitat to compensate for ecological harm caused by land clearing from, for instance, mining or urbanisation.
For example, one project in Australia relied heavily on nest boxes to offset the loss of old, hollow-bearing trees.
But a scientific review of the project showed it to be a failure, due to low rates of uptake by target species (such as the superb parrot) and the rapid deterioration of the nest boxes from falling trees.
The future of artificial refuges
There is little doubt artificial refuges will continue to play a role in confronting Earth’s biodiversity crisis, but their limitations need to be recognised, and the science underpinning them must improve. Our new review points out areas of improvement that spans design, implementation, and monitoring, so take a look if you’re involved in these sorts of projects.
We also urge for more partnerships between ecologists, engineers, designers and the broader community. This is because interdisciplinary collaboration brings together different ways of thinking and helps to shed new light on complex problems.
It’s clear improving the science around artificial refuges is well worth the investment, as they can give struggling wildlife worldwide a fighting chance against further habitat destruction and climate change.
Darcy Watchorn, PhD Candidate, Deakin University; Dale Nimmo, Associate Professor in Ecology, Charles Sturt University; Mitchell Cowan, PhD Candidate, Charles Sturt University, and Tim Doherty, ARC DECRA Fellow, University of Sydney
Adrian Dyer, RMIT University and Jair Garcia, RMIT UniversityThe intense colours of flowers have inspired us for centuries. They are celebrated through poems and songs praising the red of roses and blue of violets, and have inspired iconic pieces of art such as Vincent Van Gogh’s sunflowers.
But flowers did not evolve their colour for our pleasure. They did so to attract pollinators. Therefore, to understand why flowers produce such vibrant colours, we have to consider how pollinators such as bees perceive colour.
When observed under a powerful microscope, most flower petals show a textured surface made up of crests or “bumps”. Our research, published in the Journal of Pollination Ecology, shows that these structures have frequently evolved to interact with light, to enhance the colour produced by the pigments under the textured surface.
Bees such as honeybees and bumblebees can perceive flower colours that are invisible to us — such as those produced by reflected ultraviolet radiation.
Plants must invest in producing reliable and noticeable colours to stand out among other plant species. Flowers that do this have a better chance of being visited by bees and pollinating successfully.
However, one problem with flower colours is sunlight may directly reflect off a petal’s surface. This can potentially reduce the quality of the pigment colour, depending on the viewing angle.
You may have experienced this when looking at a smooth coloured surface on a sunny day, where the intensity of the colour is affected by the direction of light striking the surface. We can solve this problem by changing our viewing position, or by taking the object to a more suitable place. Bees, on the other hand, have to view flowers in the place they bloom.
We were interested in whether this visual problem also existed for bees, and if plants have evolved special tricks to help bees find them more easily.
How bees use flower surfaces
It has been known for some time that flowering plants most often have conical-shaped cell structures within the texture of their petal surfaces, and that flat petal surfaces are relatively rare. A single plant gene can manipulate whether a flower has conical-shaped cells within the surface of a petal — but the reason why this evolved has remained unclear.
Past research suggested the conical petal surface acted as a signal to attract pollinators. But experiments with bees have shown this isn’t the case. Other explanations relate to hydrophobicity (the ability to repel water). But again, experiments have revealed this can’t be the only reason.
We investigated how bumblebees use flower surfaces with or without conical petal shapes. Bees are a useful animal for research as they can be trained to collect a reward, and tested to see how they perceive their environment.
Bumblebees can also be housed and tested indoors, where it is easier to precisely mimic a complex flower environment as it might work in nature.
Flowers cater to a bee’s needs
Our colleague in Germany, Saskia Wilmsen, first measured the petal surfaces of a large number of plants and identified the most common conical surfaces.
She then selected some relatively smooth petal or leaf surfaces reflecting light from an artificial source as a comparison. Finally, blue casts were made from these samples, and subsequently displayed to free-flying bees.
In the experiment, conducted with bumblebees in Germany, a sugar solution reward could be collected by bees flying to any of the artificial flowers. They had to choose between flying either towards “sunlight” — which could result in light reflections affecting the flower’s coloration — or with the light source behind the bee.
The experiment found when light came from behind the bees, there was no preference for flower type. But for bees flying towards the light, there was a significant preference for choosing the flower with a more “bumpy” conical surface. This bumpy surface served to diffuse the incoming light, improving the colour signal of the flower.
The results indicate flowers most likely evolved bumpy surfaces to minimise light reflections, and maintain the colour saturation and intensity needed to entice pollinators. Humans are probably just lucky beneficiaries of this solution biology has evolved. We also get to see intense flower colours. And for that, we have pollinators to thank.
Matthew Wright, UNSW; Brett Hallam, UNSW, and Bruno Vicari Stefani, UNSWSolar power is already the cheapest form of electricity generation, and its cost will continue to fall as more improvements emerge in the technology and its global production. Now, new research is exploring what could be another major turning point in solar cell manufacturing.
In Australia, more than two million rooftops have solar panels (the most per capita in the world). The main material used in panels is silicon. Silicon makes up most of an individual solar cell’s components required to convert sunlight into power. But some other elements are also required.
Research from our group at the University of New South Wales’s School of Photovoltaics and Renewable Energy Engineering shows that adding gallium to the cell’s silicon can lead to very stable solar panels which are much less susceptible to degrading over their lifetime.
This is the long-term goal for the next generation of solar panels: for them to produce more power over their lifespan, which means the electricity produced by the system will be cheaper in the long run.
As gallium is used more and more to achieve this, our findings provide robust data that could allow manufacturers to make decisions that will ultimately have a global impact.
The process of ‘doping’ solar cells
A solar cell converts sunlight into electricity by using the energy from sunlight to “break away” negative charges, or electrons, in the silicon. The electrons are then collected as electricity.
However, shining light on a plain piece of silicon doesn’t generate electricity, as the electrons that are released from the light do not all flow in the same direction. To make the electricity flow in one direction, we need to create an electric field.
Curious Kids: how do solar panels work?
In silicon solar cells — the kind currently producing power for millions of Australian homes — this is done by adding different impurity atoms to the silicon, to create a region that has more negative charges than normal silicon (n-type silicon) and a region that has fewer negative charges (p-type silicon).
When we put the two parts of silicon together, we form what is called a “p-n junction”. This allows the solar cell to operate. And the adding of impurity atoms into silicon is called “doping”.
An unfortunate side effect of sunlight
The most commonly used atom to form the p-type part of the silicon, with less negative charge than plain silicon, is boron.
Boron is a great atom to use as it has the exact number of electrons needed for the task. It can also be distributed very uniformly through the silicon during the production of the high-purity crystals required for solar cells.
But in a cruel twist, shining light on boron-filled silicon can make the quality of the silicon degrade. This is often referred to as “light-induced degradation” and has been a hot topic in solar research over the past decade.
The reason for this degradation is relatively well understood: when we make the pure silicon material, we have to purposefully add some impurities such as boron to generate the electric field that drives the electricity. However, other unwanted atoms are also incorporated into the silicon as a result.
One of these atoms is oxygen, which is incorporated into the silicon from the crucible — the big hot pot in which the silicon is refined.
When light shines on silicon that contains both boron and oxygen, they bond together, causing a defect that can trap electricity and reduce the amount of power generated by the solar panel.
Unfortunately, this means the sunlight that powers solar panels also damages them over their lifetime. An element called gallium looks like it could be the solution to this problem.
A smarter approach
Boron isn’t the only element we can use to make p-type silicon. A quick perusal of the periodic table shows a whole column of elements that have one less negative charge than silicon.
Adding one of these atoms to silicon upsets the balance between the negative and positive charge, which is needed to make our electric field. Of these atoms, the most suitable is gallium.
Gallium is a very suitable element to make p-type silicon. In fact, multiple studies have shown it doesn’t bond together with oxygen to cause degradation. So, you may be wondering, why we haven’t been using gallium all along?
Well, the reason we have been stuck using boron instead of gallium over the past 20 years is that the process of doping silicon with gallium was locked under a patent. This prevented manufacturers using this approach.
But these patents finally expired in May 2020. Since then, the industry has rapidly shifted from boron to gallium to make p-type silicon.
In fact, at the start of 2021, leading photovoltaic manufacturer Hanwha Q Cells estimated about 80% of all solar panels manufactured in 2021 used gallium doping rather than boron — a massive transition in such a short time!
Does gallium really boost solar panel stability?
We investigated whether solar cells made with gallium-doped silicon really are more stable than solar cells made with boron-doped silicon.
To find out, we made solar cells using a “silicon heterojunction” design, which is the approach that has led to the highest efficiency silicon solar cells to date. This work was done in collaboration with Hevel Solar in Russia.
We measured the voltage of both boron-doped and gallium-doped solar cells during a light-soaking test for 300,000 seconds. The boron-doped solar cell underwent significant degradation due to the boron bonding with oxygen.
Meanwhile, the gallium-doped solar cell had a much higher voltage. Our result also demonstrated that p-type silicon made using gallium is very stable and could help unlock savings for this type of solar cell.
To think it might be possible for manufacturers to work at scale with gallium, producing solar cells that are both more stable and potentially cheaper, is a hugely exciting prospect.
The best part is our findings could have a direct impact on industry. And cheaper solar electricity for our homes means a brighter future for our planet, too.