Philippa Kaur

We contend that it is conventional farming, not the conservation policies of the European Union, that is driving most of the biodiversity loss both inside the EU and outside it (see I. Bateman and A. Balmford Nature 618, 671–674; 2023). In our view, the authors’ proposal to use land sparing to mitigate trade-offs between agriculture and biodiversity is overly simplistic.
Competing Interests
The authors declare no competing interests. More

Australia’s feral horses are a danger to species already deemed at risk of extinction.Credit: Brook Mitchell/Getty

Ecologists are welcoming recommendations from the Australian Senate to strengthen legal protections for wildlife threatened by feral horses in the Australian Alps, where they are harming vulnerable species and a unique and delicate ecosystem.Many scientists say that culling feral horses (Equus caballus) is necessary to prevent environmental damage and the extinction of species. But conflicting state and federal government laws have allowed the growth of a 25,000-strong population of feral horses across the Australian Alps region in southeast Australia, including within designated national parks. “If feral horse populations are not urgently managed, there is a real risk of losing this unique landscape and the native species that call it home,” the report states. It was released on 13 October by the senate standing committee on environment and communications, who began an inquiry on the impact of feral horses in February.The guidance includes a recommendation to recognize the threat that feral horses pose as a ‘key threatening process’ in the national Environment Biodiversity and Conservation Act (1999). It also calls for additional monitoring and assessment of the damage that feral horses are causing, and the resumption of aerial shooting of feral horses in New South Wales (NSW), where the method is currently banned. The recommendations mark the first time that the federal government has weighed in on the issue.Urgent action required“I am extremely pleased to see the senate recommend that the federal government needs to take urgent action on a whole range of fronts to try to undo the ecological disaster that feral horses have been allowed to become,” says Don Driscoll, an ecologist at Deakin University in Melbourne, Australia. He adds that the recommended boost to funding for better management of the problem is “among the most important” of the recommendations.
Australian scientists call for ‘feral horse’ culls in alpine national park
But some ecologists and policy experts say the recommendations don’t go far enough. Thomas Newsome, an environmental scientist at the University of Sydney, Australia, says that while the report acknowledges the urgency of the situatiuon, “many of the recommendations and steps will take a considerable amount of time to achieve”, especially given the proposed changes to legislation. Improvements “on the ground” will require considerable effort and a willingness to fast-track the key recommendations, he adds.Sarah Clement, an environmental policy researcher at the Australian National University in Canberra, Australia, says that it is unclear whether adding feral horses to the national list of key threatening processes will make any difference to management. Such listings “haven’t been used in many cases to date to trigger action”, she says. “It’s not clear if or how they would here.” She also notes that horse are in fact already included in the key threatening processes list under ‘novel biota and their impact on biodiversity’.Soaring populationsEuropeans introduced horses to Australia in the late eighteenth century. But feral horse numbers in the Australian Alps — which stretches across NSW, Victoria and the Australian Capital Territory (ACT) in the southeast of the country — have soared over the past two decades.That is increasing pressure on the delicate alpine ecosystem, where flora and fauna did not evolve to withstand the presence of large, hard-hoofed herbivores. “There are areas that should be lush with tall tussock grasses and streams,” says Driscoll, who has studied the effects of the feral horses in the Alps1. Now, these areas look like heavily grazed paddocks.“We have to act on this now. Because the problem is rapidly getting much, much worse,” says Christopher Johnson, a conservation biologist at the University of Tasmania in Hobart, Australia.
Ancient DNA points to origins of modern domestic horses
Feral horses are a danger to 12 of 14 species of vertebrate already deemed at risk of extinction in the Alps, including the northern and sourthern corroboree frogs (Pseudophryne pengilleyi and P. corroboree), the alpine she-oak skink (Cyclodomorphus praealtus) and four species of Galaxias fish. “Horses might be the thing that makes them finally go extinct,” says Johnson, who is also a member of the national threatened species scientific committee.But some community groups, as well as a dissenting report by senators of the conservative coalition government, maintain that wild horses — known locally as brumbies — have roamed the region for decades and belong there as a part of Australia’s cultural heritage. NSW’s Kosciuszko Wild Horse Heritage Act, passed in 2018, requires horses to be protected at a sustainable level.In additional comments tabled in the report, David Pocock, the independent senator for the ACT who instigated the inquiry, called for the repeal of the Act, which he says presents “the biggest threat to the Australian Alps”. He also recommended that NSW and Victoria adopt the ACT government’s “zero-tolerance” approach to feral horse management.

Some Australians think of ‘brumbies’ as part of the national heritage.Credit: William West/AFP via Getty

Management mismatchIn Australia, most national parks are controlled by state and territory governments. So far, the management of feral horse populations has been left to them, despite the federal government being responsible for stopping invasive species and protecting vulnerable ones.The ACT has eliminated feral horses from its national parks, killing horses that stray in from NSW, and rangers in Victoria’s national parks, which have around 6,000 horses, have reduced numbers by capturing and rehoming the animals, or by shooting them on the ground. But in NSW’s Kosciuszko National Park, control methods have been inadequate, especially in its inaccessible northern areas. The park counted 18,000 horses in 2022, the largest number and highest density in the Alps and a huge increase from the 2,000 counted in 2003.A state management plan put it in place in 2021 required Kosciuszko National Park to reduce numbers to 3,000 by 2027. But modelling obtained by the Invasive Species Council, a charity in Katoomba, Australia, estimates that this reduction would require the removal of almost 6,000 horses per year. The park is currently removing just 1,000 horses a year — meaning that the population could hit 33,000 by 2027.The latest guidance from the federal government is non-binding. But scientists and conservationists hope that it will spur stronger, more unified action across the states to stop the damage caused by the horses, and pave the way for strengthened federal legislation to limit the spread of invasive species and prevent the extinction of native flora and fauna.Aerial cullingScientists are applauding the report’s recommendation that NSW’s wild horse management plan be updated to allow horses to be shot at from helicopters. NSW banned the practice after an incident in 2000 when a horse was found injured but alive five days after an aerial cull.Many researchers say that aerial culling is the best tool available for controlling horse numbers. In the vast, rugged landscape of the Alps, measures such as ground shooting or trapping and removal are less effective and too expensive, says Jack Gough, advocacy manager at the Invasive Species Council. “The horses are in such high numbers and they’re in places that are hard to get to,” adds Driscoll. A study on the effectiveness of sterilizing female horses found that it would take between 10 and 20 years for horse numbers to fall2.
10 startling images of nature in crisis — and the struggle to save it
Aerial shooting is used to control horses and camels in Central Australia, as well as feral deer in NSW, notes Newsome. A 2017 study of aerial shooting of horses and camels in Central Australia found that most horses died instantly3. Even before today’s guidance was announced, NSW was considering allowing aerial shooting of feral horses.Community support for aerial shooting is crucial, says David Berman, an ecologist at the University of Southern Queensland who served on the scientific advisory panel for the Kosciuszko Wild Horse Management plan. Without broad support, he adds, there could be another backlash against the horse cull, which could jeopardise the use of aerial shooting of horses elsewhere in Australia. “It could be a disaster,” he says.Some scientists say that the latest guidance is just the beginning of what now needs to happen. Gough says that NSW’s Kosciuszko Wild Horse Heritage Act should be repealed so that horses can be controlled more aggressively.But he says that “unless aerial shooting is approved by [NSW Environment Minister Penny] Sharpe, and federal [Environment] Minister [Tanya] Plibersek is prepared to stump up serious funding, all this talk will not make a difference to the rapidly rising feral horse population.” More

Scientists who ran separate analyses on a single data set about the effect of grass cover on Eucalyptus seedlings arrived at vastly different answers.Credit: Laurence Dutton/Getty

In a massive exercise to examine reproducibility, more than 200 biologists analysed the same sets of ecological data — and got widely divergent results. The first sweeping study1 of its kind in ecology demonstrates how much results in the field can vary, not because of differences in the environment, but because of scientists’ analytical choices.“There can be a tendency to treat individual papers’ findings as definitive,” says Hannah Fraser, an ecology meta researcher at the University of Melbourne in Australia and a co-author of the study. But the results show that “we really can’t be relying on any individual result or any individual study to tell us the whole story”.
Replication games: how to make reproducibility research more systematic
Variation in results might not be surprising, but quantifying that variation in a formal study could catalyse a larger movement to improve reproducibility, says Brian Nosek, executive director of the Center for Open Science in Charlottesville, Virginia, who has driven discussions about reproducibility in the social sciences.“This paper may help to consolidate what is a relatively small, reform-minded community in ecology and evolutionary biology into a much bigger movement, in the same way as the reproducibility project that we did in psychology,” he says. It would be hard “for many in this field to not recognize the profound implications of this result for their work”.The study was published as a preprint on 4 October. The results have not yet been peer reviewed.Replication studies’ rootsThe ‘many analysts’ method was pioneered by psychologists and social scientists in the mid-2010s, as they grew increasingly aware of results in the field that could not be replicated. Such work gives multiple researchers the same data and the same research questions. The authors can then compare how decisions made after data collection affect the types of result that eventually make it into publications.The study by Fraser and her colleagues brings the many-analyst method to ecology. The researchers gave scientist-participants one of two data sets and an accompanying research question: either “To what extent is the growth of nestling blue tits (Cyanistes caeruleus) influenced by competition with siblings?” or “How does grass cover influence Eucalyptus spp. seedling recruitment?”
How to make your research reproducible
Most participants who examined the blue-tit data found that sibling competition negatively affects nestling growth. But they disagreed substantially on the size of the effect.Conclusions about how strongly grass cover affects numbers of Eucalyptus seedlings showed an even wider spread. The study’s authors averaged the effect sizes for these data and found no statistically significant relationship. Most results showed only weak negative or positive effects, but there were outliers: some participants found that grass cover strongly decreased the number of seedlings. Others concluded that it sharply improved seedling count.The authors also simulated the peer-review process by getting another group of scientists to review the participants’ results. The peer reviewers gave poor ratings to the most extreme results in the Eucalyptus analysis but not in the blue tit one. Even after the authors excluded the analyses rated poorly by peer reviewers, the collective results still showed vast variation, says Elliot Gould, an ecological modeller at the University of Melbourne and a co-author of the study.Right versus wrongDespite the wide range of results, none of the answers are wrong, Fraser says. Rather, the spread reflects factors such as participants’ training and how they set sample sizes.So, “how do you know, what is the true result?” Gould asks. Part of the solution could be asking a paper’s authors to lay out the analytical decisions that they made, and the potential caveats of those choices, Gould says.Nosek says ecologists could also use practices common in other fields to show the breadth of potential results for a paper. For example, robustness tests, which are common in economics, require researchers to analyse their data in several ways and assess the amount of variation in the results.But understanding how analytical variation sways results is especially difficult for ecologists because of a complication baked into their discipline. “The foundations of this field are observational,” says Nicole Nelson, an ethnographer at the University of Wisconsin–Madison. “It’s about sitting back and watching what the natural world throws at you — which is a lot of variation.” More

High-quality research from scientists in Australia, New Zealand and parts of Scandinavia tends to lean the most heavily towards tackling climate and conservation issues, according to an analysis of data in the Nature Index.Of research published from 2015 to 2022 in 82 natural-science journals tracked by Nature Index, 4.7% of articles align with the four United Nations Sustainable Development Goals (SDGs) that are most closely related to climate change and conservation.Some of the leading 25 countries and territories for publishing this research, however, are way ahead of this global average (see ‘Green focus’). The interactive chart shows the proportion (climate and conservation %) of a country or territory’s total Nature Index output (measured by the Nature Index metric Share) that aligns with SDGs on Responsible Consumption and Production (SDG 12), Climate Action (SDG 13), Life Below Water (SDG 14) and Life On Land (SDG15).

Almost one-fifth of Nature Index research published by Norway, for instance, is related to these SDGs, and 14.5% of New Zealand’s output in the database align with the four goals. Finland and Denmark also have a high proportion of their research related to these topics.
Nature Index 2023 Climate and conservation
These countries do have a relatively low volume of research output for SDGs 12–15 (as shown by the size of the bubbles), but Australia (10.4%) is notable for having higher output that is also well above the global average.The biggest publishers of high-quality climate and conservation research — the United States and China — are closer to the global average, but fall either side of this line. Japan, meanwhile, is an example of a country with relatively high volume, but well below the average as a proportion of its total Nature Index output.Digging into the data shows how this research breaks down between the four SDGs for each country and territory.The following interactive charts (see ‘Goal specific’) show the proportion of a location’s total climate and conservation output in the Nature Index that relates to each SDG (SDG as proportion of all climate and conservation output), with the size of the bubbles showing the volume (measured by the Nature Index metric Share).

SDG 13 (Climate Action) tends to represent the greatest proportion of research on the wider topic: globally, 62% of all Nature Index output aligned with SDGs 12 to 15 aligns with SDG 13. The United States and China are both ahead of the average, but many countries in Europe lag behind. India has the highest percentage of its climate and conservation research in SDG 13.Countries with easy access to extensive coastlines are among those with a skew towards SDG 14 (Life Below Water), including Australia, France and the United Kingdom, whereas Brazil, with its research focus on the Amazon rainforest, is an outlier for SDG 15 (Life On Land).SDG 12 (Responsible Consumption and Production) tends to represent the smallest proportion of climate and conservation research, but Singapore and Belgium are the furthest ahead of the global average.Data on research articles and their SDG alignment come from Digital Sciences’ Dimensions platform, which uses machine learning to automatically tag research papers if they align to certain SDGs. Some articles are tagged to more than one SDG, so percentages may not add up to 100. More

My workspace at the University of Peradeniya, Sri Lanka, includes shelves stacked with rare, preserved plant specimens. But I also work in the country’s lush forests, a tropical biodiversity hotspot filled with a trove of indigenous plants. My passion for scouting the forests for herbs escalated in 2016, when I joined the National Herbarium in Kandy, Sri Lanka, as a project assistant for the national botanical survey.I realized that, on my island nation, there are many understudied herb families. I am studying one of these, Piper, for my PhD, collecting samples from the Walankanda forest. In March 2021, a researcher working there sent me photographs of a flower. At first, it seemed to belong to the Zingiberaceae, or the ginger family, but its leafless nature then suggested otherwise. An analysis revealed that this species was a previously uncharacterized terrestrial orchid. In this photo, I’m holding a preserved specimen of it.This orchid is non-photosynthetic and relies entirely on symbiotic fungi for nutrients. It has a three-week flowering period during which the flowers stay in bloom for only three days. This makes it challenging to identify. I relied on an island-wide network of early-career researchers for data collection — their help was crucial to bring this new species to light.I named it Gastrodia pushparaga, after the pushparaga yellow sapphire that is found in my country. Not only because the amber-hued flower, streaked with red, resembles the gemstone, but also because discoveries of indigenous species are precious assets to Sri Lankan biodiversity. This remarkable discovery by a team of young scientists comes at a time when academia in my country is severely challenged by an economic crisis and an exodus of researchers to wealthier countries. With few botanists around to study herb families in Sri Lanka, my goal is to keep unravelling the taxonomies of these plants. More

RESEARCH BRIEFINGS
04 October 2023

Amphibians are the most vulnerable vertebrates worldwide, with 41% of species threatened with extinction. Habitat loss is the most common threat, and climate change is the main driver of increased extinction risk. Investment in amphibian conservation must be scaled up drastically and urgently to prevent further extinctions and reverse declines. More

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Human activities are driving the Amazon towards the limits of survival.Credit: Ueslei Marcelino/Reuters

Earth is at the start of a mass extinction event: estimates show that species are disappearing at 100–1,000 times the rate of naturally occurring extinctions1,2. It will be the sixth such event in Earth’s 4.5-billion-year history. Unlike the previous five, this one has been precipitated by the actions of one species — humans.The 15th of the 17 Sustainable Development Goals (SDGs) agreed by the United Nations, which Nature is covering in a special series, aims to reverse this looming crisis on land. SDG 15’s aims are “to protect, restore and promote sustainable use of terrestrial ecosystems, sustainably manage forests, combat desertification, and halt and reverse land degradation and halt biodiversity loss”.
Progress towards the Sustainable Development Goals
As we have already reported in this series, progress towards a similar goal — SDG 14, to protect life below water — is going backwards. SDG 15 is also nowhere near on track. In 2019, the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) — an organization similar to the Intergovernmental Panel on Climate Change — reported3 that ecological communities on land have lost more than 20% of their original biodiversity, and that millions of terrestrial species are likely to become extinct by 2100.The greatest driver of this loss is conversion of land on an industrial scale for human use, especially by agribusiness and industry. Every year, human activities are costing the world around 100 million hectares of natural land — and about that much forest was lost between 2000 and 2020.There is a small silver lining: the number of countries that are tracking biodiversity as part of their official statistics has been steadily increasing, one of SDG 15’s targets. Tracking is necessary — but on its own, it is only a partial answer. A bigger issue is that the costs of environmental damage, such as biodiversity loss, rarely factor into countries’ official calculations of income and wealth. If anything, clearing a forest to build housing, grow crops or construct infrastructure to exploit fossil fuels is considered a net economic gain. An analysis of progress towards the 17 SDGs in 99 lower-income nations, published this year, confirms this: gains in reducing poverty and improving human welfare have come at a high price to the environment4. The current system is weighted towards destruction, not preservation. Now is an important moment to make a quiet revolution louder.Margins to mainstreamFor decades, researchers and policymakers have worked painstakingly to integrate environmental indicators more closely with economic ones. Their project, the System of Environmental Economic Accounting (SEEA), has become the world’s standard for measuring nature’s contribution to the economy and the impact of economic activity on the environment. It was adopted by the UN in 2012, was updated in 2021 and is now in use in 92 countries and rising. The SEEA measures stocks of environmental assets, such as a country’s forest and mineral resources, along with ‘flows’, such as the quantity of water consumed by industry.
What scientists need to do to accelerate progress on the SDGs
Most countries report these results in ‘satellite’ accounts, which measure economic sectors that are not considered industries in national accounts. Australia, for instance, publishes a national state of the environment report every five years. Canada publishes annual ecosystem accounts covering 30 variables, from road density to the numbers of people using cultural services. Uganda measures how much land is covered by grasslands, woodlands and commercial farmlands, as well as the extent of suitable habitat for important species, such as the shea tree (Vitellaria paradoxa) and the African cherry (Prunus africana).This hard work has paid off: these data, watched and used by researchers and policymakers in conservation-related fields, are now on the radar of those in finance and economic decision-making roles.The UN Statistics Division, based in New York City, is seeking expert comments on the next revision to the System of National Accounts (SNA). This is the international statistical standard used to measure economic activity — consumer and government spending and investments by businesses. There have been just 3 revisions in the SNA’s 70-year history. Now, questions about how the SNA can account for environmental sustainability, along with well-being, are being considered. If the SEEA and the SNA can be linked more closely, this could lead economic policymakers to pay closer attention to biodiversity loss, climate impacts and other costs. This revision is the chance for researchers and others who care about these issues to have their say (see go.nature.com/3tiucxt). The deadline is 9 October.Make no mistake, the costs of failing to account for the environment are high, and they are here now — but they are hidden from our daily lives and concerns. A systematic approach to addressing these trade-offs is not the only answer to achieving the SDGs, but it is necessary. Properly resourcing national statistical offices to coordinate environmental accounts is also essential. Those who make economic policy decisions need to see the environmental wealth that is being whittled away as a direct result of those decisions. Only then do we stand even a remote chance of halting the sixth mass extinction event. More