Soil Fertilization With Amazonian Dark Earth Increases Tree Diameter By Up To 88%

33-month-old acacias in Manaus: ADEs result from the decomposition of organic matter and the use of fire by pre-Columbian populations and continue to be created by present-day peoples CREDIT: Tsai Siu Mui/CENA-USP



April 29, 2026 
By Eurasia Review


A study conducted in the Brazilian state of Amazonas with support from FAPESP demonstrated that small amounts of Amazonian dark earth (ADE) – an anthropogenic soil created by ancient Amazonian populations – can increase the height and diameter of the pink trumpet tree (Handroanthus avellanedae) by up to 55% and 88%, respectively. This tree also occurs in the Atlantic Forest.

For the Brazilian firetree (Schizolobium amazonicum), the increase was 20% in height and 15% in trunk diameter. These results refer to the first 180 days of life for these plants, compared to other plants of the same species that did not receive dark earth.

The study was published in the journal BMC Ecology and Evolution and was conducted by researchers from the Center for Nuclear Energy in Agriculture of the University of São Paulo (CENA-USP) in Piracicaba; Embrapa Eastern Amazon, one of the decentralized units of the Brazilian Agricultural Research Corporation (EMBRAPA), in Manaus; and the National Institute for Amazonian Research (INPA), also in Manaus, the capital of the state of Amazonas.

“The key factor was not the amount of nutrients per se, which doesn’t vary much, but rather the microorganisms, which were quite different, especially the fungi. In plants treated with dark earth, the microbiota around the roots reorganizes, with more efficient recruitment of beneficial microorganisms and a reduction in pathogens,” explains Anderson Santos de Freitas, the first author of the study. He conducted the research during his doctoral studies at CENA-USP with a scholarship from FAPESP.

In addition to helping to reforest degraded areas and provide ecosystem services, the two analyzed trees can be used for sustainable timber harvesting, especially the pink trumpet tree.

The study is part of the “Soil-plant feedbacks in the Amazon Forest under agricultural systems in the state of Amazonas” project, which is supported by FAPESP and coordinated by Tsai Siu Mui, a professor at CENA-USP.

Ancestral land

Amazonian dark earths, also known as terras pretas de índio (TPIs), result from the decomposition of organic matter and the use of fire by pre-Columbian populations. These earths continue to be formed by present-day peoples.

The study shows that ADEs harbor a variety of bacteria, archaea, and fungi that help plants absorb nutrients and eliminate other opportunistic and pathogenic microorganisms, creating a more favorable environment for growth.

“We’ve been studying dark earths for over 20 years and have tested various ways of using them. The idea is to understand what makes them best suited for helping trees grow faster and stronger in degraded areas,” says Tsai.

“When land is deforested, especially for pasture, the soil tends to be poorly managed, leading to a rapid loss of microorganisms and nutrients. The goal is to restore the forest and ecosystem services in these areas,” she adds.

Dark earths are protected by law and regulated by the Genetic Heritage Management Council (CGen), a collegiate body chaired by the Ministry of the Environment and Climate Change.

“We use small amounts in our experiments after obtaining authorization from CGen. The idea isn’t for people to use it directly, which is prohibited, but rather to understand how it’s formed, what its composition is, and which microorganisms and processes make it so special. With this knowledge, we could reproduce it or isolate its useful components,” says Freitas.

Experiment

In a previous study, the group compared the growth of seedlings from other tree species and Brachiaria grass in a greenhouse with and without the addition of dark earth.

In the current study, seedling growth was measured in the field. Seeds from the two species were grown in the Embrapa Eastern Amazon nursery in Itacoatiara, Amazonas, under two treatments: dark earth or coconut fiber.

Fifteen days later, the seeds had germinated and developed into seedlings. These seedlings were then transferred to the experimental field of the same institution in Manaus. The seedlings were planted in the soil and received no fertilizer or herbicide; they relied solely on rainwater and manual weed control.

After six months, all the plants were alive. However, the ADE-treated plants showed significant differences. Although the firetrees showed proportionally slower growth than the pink trumpet trees, they were about 1.5 meters tall 180 days after the seedlings were transferred to the field.

The researchers observed an increase in fungal diversity in the soil of the plants treated with dark earth, which was more pronounced in the purple trumpet trees. This may be explained by the high adaptability of firetrees to degraded soils, meaning the species does not require as many nutrients and microorganisms.

“Fungi respond more quickly because they’re more complex microorganisms. With the addition of dark earth, there’s an immediate increase in organic matter and, therefore, decomposing fungi, which cycle nutrients more efficiently and make them more available to plants,” Freitas explains.

The results, which have now been published, refer to the first 180 days of life for the plants. The experiment lasted a total of three years. Currently, the researchers are analyzing data from the entire period, which will lead to new studies.

Over the course of more than 20 years of studying dark earths, the laboratory led by Tsai at CENA-USP has isolated over 200 microorganisms from these formations. These microorganisms are currently being analyzed for their functions. The goal is to develop solutions for restoring degraded soils for reforestation.

Decline In Prey Increases Risk Of Jaguar Extinction In Atlantic Forest

In the Green Corridor, ongoing conservation initiatives such as the Iguaçu Jaguar Project and long-term efforts to combat illegal hunting help maintain a prey base capable of sustaining viable jaguar populations CREDIT: Iguaçu Jaguar Project


April 29, 2026 
By Eurasia Review

In addition to habitat loss and illegal hunting, the jaguar (Panthera onca) faces another threat that increases its risk of extinction in the South American Atlantic Forest: food scarcity.



A study by Brazilian researchers found that the availability of jaguar prey is reduced, even in the protected areas of the biome, which covers approximately 15% of Brazil and extends across 17 states in the South, Southeast, and Northeast regions, as well as parts of Argentina and Paraguay.

Jaguar prey species, including peccaries (Tayassu pecari), agoutis (Dicotyles tajacu), and deer, are hunted by humans and have dwindled to numbers that likely cannot support viable jaguar populations in the Atlantic Forest. The researchers warn that if this situation worsens, the biome, which currently has fewer than 300 jaguars, could become the first in the world to lose a top predator.

The results of the study, which was supported by FAPESP were published in an article in the journal Global Ecology and Conservation. The study also involved researchers from the Cananeia Research Institute (IPeC), the Chico Mendes Institute for Biodiversity Conservation (ICMBio), as well as its National Center for the Research and Conservation of Carnivorous Mammals (CENAP/ICMBio), the State University of Mato Grosso (UNEMAT), and the Iguaçu Jaguar Project – Pro-Carnivores Institute.

“We found an alarming situation of low abundance of key prey species for the jaguar even in protected areas of the Atlantic Forest, where national and state parks are located and where one would expect the situation in terms of the animal’s conservation to be better,” Katia Ferraz, a professor at the Luiz de Queiroz School of Agriculture at the University of São Paulo (ESALQ-USP) and coordinator of the study, tells Agência FAPESP. “Most likely, the decline of these prey species is one of the main causes of the critical conservation situation facing the jaguar in this biome,” she notes.

Field survey

The researchers combined information on the jaguar’s diet and feeding habits with data obtained through an on-site survey of the feline’s prey species. They did this using camera traps distributed across nine protected areas in the Atlantic Forest. Based on the data, they estimated the abundance and biomass of 14 prey species in these areas, which have varying levels of jaguar populations, and made comparisons between them.

The analyses revealed that the largest feline in the Americas primarily feeds on large prey, particularly wild pigs and deer. These prey were more abundant and had higher biomass in the Green Corridor than in the Coastal Atlantic Forest regions, such as the Serra do Mar, where jaguars are absent or occur at very low densities. The data reveal a striking difference in biomass between the Green Corridor (638 kg) and the coastal regions (8.2 kg).

“The results show a consistent pattern. Areas with greater prey availability, especially of medium- and large-sized prey such as wild pigs and deer, are also those where jaguars persist. Where the prey base is very limited, jaguar populations tend to be absent or extremely small,” notes Ferraz.
Easier access

According to the researcher, the low abundance and reduced biomass of the analyzed species were due to human presence. Prey were more abundant in areas that were more difficult to access and less abundant where illegal hunting was easier, indicating that this activity remains a core problem, even within conservation areas.

“We’ve observed that the low availability of prey is linked to increased human access to protected areas. In areas that are more easily accessible due to factors such as terrain and proximity to villages and urban centers, prey availability is lower,” says Ferraz. “This suggests a direct link to hunting pressure. In addition to the pressure on the jaguar itself, the predator, there’s very strong pressure on prey populations, leading to the decline of the feline,” she explains.

In the Green Corridor, protected areas are more connected and less accessible to human activity. Ongoing conservation initiatives, such as the Iguaçu Jaguar Project, and long-term efforts to combat illegal hunting also help explain why there is a prey base capable of sustaining viable jaguar populations.

In the coastal portion of the biome, such as the Serra do Mar, the low abundance of prey may reflect historical and still-persistent human pressure, despite the vast territorial extent and numerous ongoing conservation efforts, whether government-led or not. The authors of the study note that this reality is linked to the region’s proximity to major urban centers, such as Curitiba and São Paulo, and to the greater ease of access to protected areas.

According to the authors, this scenario poses a core challenge to environmental management. While some regions function as refuges that maintain ecological balance, others require intensive actions to control hunting, recover wildlife, and manage human use to prevent the permanent disappearance of the Americas’ largest predator in the Atlantic Forest.
Conservation oases

Of the areas evaluated in the study, Iguaçu National Park stood out as one of the last places in the Atlantic Forest with relatively high populations of predators and prey.


The successful conservation of jaguars in the park is due to a combination of human and ecological factors, including the work of the Iguaçu Jaguar Project and altitude. “Across all the areas analyzed, it was observed that the lower the altitude, as in the park, the greater the abundance of prey – a pattern also recorded in other areas of the Atlantic Forest,” explains Ferraz.

The Iguaçu Jaguar Project is based on three pillars: research, coexistence, and engagement. In the research area, applied studies are conducted to inform effective strategies on topics such as food ecology, vegetation corridors, and monitoring.

The engagement pillar aims to transform fear into understanding and fascination with jaguars, strengthening the bond between local communities and conservation efforts. The coexistence pillar involves working with communities surrounding the park to offer guidance on best practices for livestock management, preventing predation, and reducing misinformation. When there are reports of sightings or tracks, immediate guidance on safety and appropriate behavior is provided.

“Jaguars here in the region were nearly extinct. In 2009, we had between nine and 11 animals, and over the past 15 years, the population has nearly doubled,” says Yara Barros, the executive coordinator of the project. One of the actions that contributed to this result was precisely the increased effort to combat illegal hunting. “Hunting poses a major threat because people often enter the forest to hunt the animal’s prey and end up killing it as well,” she says.

The increase in agriculture and decrease in cattle ranching around the park may have also contributed to the recovery of the species, as the change in land use has reduced retaliatory killings. “We collaborate with communities in ten municipalities. A project technician visits rural properties not only when predation occurs,” says Barros.

According to Barros, coexistence is key: “We’re creating a tri-national network with partners from Paraguay and Argentina to share and replicate our experience,” she says.

PM Carney points to trade irritants with U.S.: ‘Those are violations of our trade deal’

By Rachel Aiello
Updated: April 23, 2026 



OTTAWA -- As top U.S. trade officials revive talk of Canadian trade irritants — such as provincial booze bans — Prime Minister Mark Carney says Canada has its own issues with the Americans, which he wants to see addressed.

“Look, you know what’s an irritant? A 50 per cent tariff on steel, 50 per cent tariff on aluminum, 25 per cent tariff on automobiles, all the tariffs on forest products,” Carney said Thursday, at a housing announcement in Ottawa.Live updates: PM Carney says U.S. trade irritants ‘right there in front of us.’

“Those are more than irritants,” he said. “Those are violations of our trade deal.” Carney pointing to these specific U.S. trade actions against Canada comes amid ramped-up gripes by U.S. President Donald Trump’s team that several provinces continue to prohibit the sale of American alcohol on liquor store shelves, and questions about whether that may be a barrier to successful trade talks.

These bans on U.S.-made booze are also a contravention of the two countries’ trade agreement, in the eyes of the Americans. But when asked Thursday if he intends to lean on provincial leaders — namely Ontario Premier Doug Ford — to ease off, the prime minister pushed back.

“Surprise, surprise, the premier of Ontario is influential with the LCBO, okay, but he’s the client,” Carney said. “He’s also the duly elected premier of Ontario. He’s got a majority, and he’s taking a view which, you know, by most indications, is supported by the vast majority of the population.”


“What we want to do is make progress as the whole,” he added. “These issues, issues such as decisions on which alcohol to put on the shelves, we can make progress very quickly on that, with progress in other areas.”

Carney continued, saying he is looking to negotiate something that is “mutually agreeable,” and that there “will be adjustments,” but that “when we make progress,” it’ll be up to the provinces with such policies in place to make a call.

During an interview with CNN on Thursday morning, Ford was asked to respond to U.S. Commerce Secretary Howard Lutnick, recently calling the ongoing boycott of U.S. alcohol “insulting and disrespectful to America.”

“I guess what is disrespectful is we never started this tariff war and I don’t believe the American people did. It was Secretary Lutnick followed by President Trump as well that attacked our joint economies,” Ford said Thursday.

Ford has previously said that Ontario will not lift its ban on U.S. alcohol at provincial liquor stores until all new tariffs on Canadian goods are removed.
PM Carney slaps down ‘entry fee’ talk

And, amid reporting from a few major outlets suggesting the Americans are angling for some form of so-called Canadian “entry fee” — or immediate concession — to begin trade talks, Carney says he’s at a loss where that suggestion may be coming from.

“I don’t know where the talk of a ‘entry fee’ is from, certainly not coming from me. It’s not language I’ve ever used, and it’s not language I’ve ever heard from the president of the United States,” Carney said. “It’s a negotiation,” he added. “These things have their own rhythm, and they also have what’s happening above the surface and what’s happening below the surface, and we’ll see in the fullness of time.”

“Our work is… to be prepared on all of the issues to provide our perspective,” Carney said. “We’re also ready to wait. If that’s what has to happen.”

The trilateral trade deal between Canada, the U.S. and Mexico, known as CUSMA, is imminently up for review by July 1. At that point, officials can decide to renew the deal for a 16-year period, or to agree to an annual review process.

On Parliament Hill on Thursday, Conservative Leader Pierre Poilievre noted Carney’s comments dismissing any suggestion of an “entry fee,” and when asked if he thinks Canada should put U.S. wine, beer and liquor back on store shelves, Poilievre said “no.”

Poilievre said that Carney has already “squandered all of our leverage” and he doesn’t think Canada should “squander any more.”

“I don’t think we need to spend three or four days debating whether we should drink bourbon or not. I think we should discuss whether 2.6 million Canadians are going to have their jobs, and the way to get those jobs secured is to get a tariff-free trade deal with the U.S.,” he said.
Americans want concessions

The Americans have long made clear — dating back to last December and reiterated earlier this month — that they will be looking for Canada to make concessions in the CUSMA review process.

U.S. Trade Representative Jamieson Greer, speaking to the U.S. House Ways and Means Committee on Wednesday, repeated a position he’s laid out before, that the U.S. doesn’t “want to rubber-stamp it,” without addressing specific issues.

Beyond booze, another issue the Americans have said they’ll be pushing Canadian officials on, is expanding access to this country’s supply managed dairy market.

Canada allows a limited amount of U.S. dairy to enter tariff-free under CUSMA, but Greer doesn’t think that’s enough.

Canada-U.S. Trade Minister Dominic LeBlanc has already said publicly that dairy supply management concessions are off the table, a position Carney reiterated Thursday.

Greer has also cited Canada’s Online Streaming Act, which he’s said “discriminates against U.S. tech and media firms,” and the Online News Act, as irritants. Both Justin Trudeau-era laws bring streaming and digital news platforms under Canadian cultural and broadcasting rules.

“We’ve been very clear on supply management, on our cultural rights,” Carney said, going on to state Canada will be “defending” those elements.


Rachel AielloOpens in new window

National Correspondent, CTV News

 

Q&A: Does nature have a role in national security?

Penn State

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UNIVERSITY PARK, Pa. — The security of every nation faces an increasingly severe and frequent threat: disruptions to nature. According to Bradley J. Cardinale, professor in the Department of Ecosystem Science and Management in the Penn State College of Agricultural Sciences, disrupted ecosystems can lead to increased risk for food security, water availability, health and well-being, as well as crime.  

Cardinale, along with collaborators J. Emmett Duffy, marine biologist and chief scientist for the Smithsonian Environmental Research Center, and Rod Schoonover, ecological security expert who was a former director for the U.S. National Intelligence Council and adjunct professor in the School of Foreign Service at Georgetown University, published an assessment of 27 case studies on how disrupted ecosystems can heighten risks of societal unrest and political instability, ultimately threatening national security, in the journal Nature-Based Solutions.  

In the Q&A below, Cardinale discussed nature’s role in national security, as well as how governments can best protect against ecological disruptions. 

Q: What is nature’s role in national security?  

Cardinale: We have long known that ecosystems and the creatures that live in them provide goods and services to people. These have been referred to as “ecosystem services” or “nature’s benefits to people.” Examples include provisions like food, wood and water; mitigating impacts of climate and disease; cultural benefits, such as recreation; and support for other life-support processes, like nutrient cycling.  

In this paper, we extend these concepts to the scale of entire countries by looking at how nature influences the ability of a nation to protect its citizens, institutions and interests from domestic and foreign threats. We draw explicit links between biological forms of global change that disturb ecosystems — what we call ecological disruptions — and increased risk in five areas of national security: food security, water scarcity, health security, protection from natural disasters and environmental crime. For each aspect, we show how ecological disruptions increase social and political stress that, in turn, undermine national security.  

Q: What are ecological disruptions, and how are they caused? How do they impact national security?  

Cardinale: Ecological disruptions are intense, rapid changes to the natural or semi-natural environment that significantly alter the structure, function and biodiversity of ecosystems. Ecological disruptions are often caused by humans, such as when our activities degrade or destroy ecosystems or threaten the species that live in them. 

In this paper, we consider five types of ecological disruption, including habitat loss, overharvesting, pest and disease outbreaks, invasive species, and biodiversity loss. We discuss how these ecological disruptions generate social and political stress, as well as provide 27 well-documented case studies showing how disruptions lead to mass migrations of people, border breaches, violent protests, regional conflict, even warfare. 

Our case studies include some well-known examples like the Cod Wars that occurred after overharvesting of cod led commercial trawlers to ignore international boundaries to fish for declining stocks. The result was a military conflict between Iceland and Britain. Examples of other case studies we review include deforestation exacerbating drought and water scarcity leading to violent protests in South America, invasive species causing crop failures and famine leading to mass migration and border breaches in Africa, mismanagement of wildlife causing pandemics of infectious disease that have led to civil disorder and violent protests globally, and illegal logging and wildlife poaching that has funded drug cartels, terrorist organizations and crime syndicates in several regions around the world.   

Q: How can people protect against ecological disruptions?  

Cardinale: It would be easy to suggest that individuals can protect against ecological disruptions by conserving and restoring nature. But this recommendation would be woefully inadequate due to a mismatch in scale. The ecological disruptions we are talking about — and the implications these disruptions have for security — are national and international in scale. As such, addressing the problem requires intervention by whole governments. 

We argue in this paper that governments should build and protect natural infrastructure in the same way they build and protect physical infrastructure. Governments already understand the important role of physical infrastructure like energy grids, transportation and communications networks, and water and food systems for national security. Indeed, we go to great lengths to protect physical infrastructure from bad actors and enemies during a conflict. In contrast, most governments are just beginning to appreciate the important role of natural infrastructure — the ecosystems and biological communities that are required to meet basic human needs and prevent ecological disruptions. 

Unfortunately, just as many nations are coming to appreciate the role of nature in maintaining natural security, others are actively dismantling the agencies, scientific expertise and investments necessary to understand changes in, and therefore safeguard, critical natural infrastructure. Weakening these institutions has the potential to undermine a nation’s ability to meet the basic needs of its citizens, fueling grievances that erode trust in government and heighten instability within and among nations.  

Q: What’s next for your work in this area?  

Cardinale: There are two directions we are going at present. First, we are trying to gather more examples of how nature impacts national security. If we can get a more case studies, including a more diverse representation of national security impacts, then we can transition into the next phase of quantitative data analysis where we determine which aspects of nature most impact security and compare the role of nature to other drivers of national security. 

Second, we are building a community of practitioners who will work together at the intersection of nature and national security. There are many biologists and ecologists who already think about how ecosystems provide goods and services to humanity. But these folks rarely extend the benefits of nature to entire nations. At the same time, there are individuals who work in positions that oversee national security and appreciate that global change can alter our security forecasts. However, they don’t often talk with biologists who understand which ecosystems and species are key service providers. Getting these two groups to talk and work together will go a long way towards advancing our understanding of how nature influences national security.   

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Journal

Nature-Based Solutions

DOI

10.1016/j.nbsj.2026.100330 

Article Title

Nature’s role in national security

Article Publication Date

1-Jun-2026

Host of positive ‘tipping points’ can regenerate nature

University of Exeter

A host of positive “tipping points” can spark rapid nature recovery, a leading expert says.

Action to protect and restore nature must accelerate radically to meet global goals for 2030 and beyond.

Writing in the journal Nature Sustainability, Professor Tim Lenton says positive tipping points are key to achieving this.

He highlights potential tipping points – moments when a small change triggers a rapid, often irreversible transformation – in nature, human societies and areas where the two combine.

“The destruction and degradation of the natural world pose an existential threat,” said Professor Lenton, of the Global Systems Institute at the University of Exeter.  

“We are already crossing or approaching several dangerous ecological tipping points, including the dieback of warm-water coral reefs and the Amazon rainforest.

“But just as human activity can drive negative tipping, we can bring about positive tipping points to spark large-scale nature recovery.”

While addressing climate change is vital for protecting nature, specific social and ecological tipping points can regenerate ecosystems, spread nature-positive activities, and reduce drivers of nature loss.

Many governments are signed up to international goals to regenerate nature – such as protecting 30% by 2030 – but progress is going far too slowly. Crucially, triggering positive tipping points can help achieve the necessary acceleration in progress.

Positive tipping points offer opportunities for businesses who are trying to work out how they can have a positive impact on nature, and for finance companies who are trying to identify investable opportunities in nature regeneration.

Professor Lenton identifies four key types of positive tipping point for nature:

• Ecosystem recovery: Numerous degraded ecosystems have been positively tipped into a regenerated state. For example, reintroduction of wolves in Yellowstone National Park in 1995-6 likely led to a positive tipping point of riverbank vegetation recovery, which in turn boosted the numbers of scavengers, songbirds, bison and beavers. In Pacific kelp forests, the removal of sea otters caused sea urchin populations to escalate and kelp to collapse. Sea otter recovery (or their reintroduction, for example in Alaska) tipped kelp forest recovery.
• Social-ecological systems: Effective management of shared resources can lead to positive tipping points. For example, in pelagic (open sea) fisheries, positive tipping can be triggered by enforcing a Maximum Sustainable Yield – the highest yield that can be taken without significantly affecting reproduction. This typically requires short-term reduction in fishing, with strong enforcement. This has produced positive tipping points for recovery of plaice and hake stocks in the North Sea. In coastal fisheries, Marine Protected Areas (MPAs) can help positively tip fish stock recovery, by providing safe spawning areas and “spillover” of fish into the surrounding waters.
• Nature-positive initiatives: The social spread of nature-positive initiatives can also become “self-propelling” – an important feature of a tipping point. For example, the small-group tree planting initiative (TIST) originated in Tanzania and spread rapidly in Kenya and Uganda – and to India – aided by a structure designed to maximise autonomy and social learning, and by providing multiple benefits to adopters, including carbon payments. In another example, success on Apo Island inspired the spread of marine reserves in the Philippines via the “reinforcing feedback” of social learning.
• Consumption behaviour: Positive tipping points in patterns of consumption could reduce key drivers of nature loss. The most important driver of nature loss is agricultural expansion, primarily due to increased meat consumption. However, in several rich nations that overconsume meat, there have been significant recent reductions in meat consumption. Social norms and the quality, diversity and availability of meat-free options are key to enabling a positive tipping point. Professor Lenton also highlights strong “balancing feedbacks” that are opposing dietary change. For example, in the EU, four times as much farming subsidy goes into animal products as plant ones.

Professor Lenton said a key research opportunity is to test which current systems may be approaching a positive tipping point – potentially inspiring action to trigger it.

He identifies three levers that could enable multiple positive tipping points: facilitating online collective learning among groups taking nature-positive action, properly valuing nature in economics, and tipping worldviews to “ecocentrism”.

On the latter, Professor Lenton said: “Changing the ethical and legal status of nature is a powerful practical step to underpin nature-positive action. Such a tipping point in paradigm could be the deepest leverage point for nature-positive system change.”

The article is entitled: “Positive tipping points for nature.”

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Journal

Nature Sustainability

DOI

10.1038/s41893-026-01803-0 

Article Title

Positive tipping points for nature.

Article Publication Date

27-Apr-2026

 

Challenging the urban-rural divide in ecology

Framework focuses on need for connectivity to inform urban planning, sustainability, and human well-being

Cary Institute of Ecosystem Studies

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Instead of thinking of urban and rural as binary, the new ‘Continuum of Urbanity’ adds a third dimension (wildness) and room for mixture, so that urban planners and researchers can better understand and help the neighborhoods they work in. 

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Credit: Credit: Pickett et al./npj Urban Sustainability 2026

As cities sprawl into suburbs and exurbs, the distinction between urban areas and the countryside has become increasingly blurry. A new paper published in npj Urban Sustainability proposes that many modern landscapes can be managed more holistically when they are understood as a mixture of urban, rural, and wild features.

“There used to be a clear boundary between cities relative to the countryside and the wild, but that has been changing for a long time,” says lead author Steward Pickett, an urban ecologist and scientist emeritus at Cary Institute of Ecosystem Studies. “You can’t just walk in a straight line from a city center and define where the ‘urban’ ends.”

Pickett and coauthors put forth a new framework that emphasizes the many connections among urban, rural, and wild places that can create a blend of these features in a given area. 

“It’s like patchwork or a mosaic,” explains Pickett. “You can have a place that's 70% urban and 30% rural right next to a place that's the opposite, or has some wild mixed in.” He and his coauthors hope this new way of thinking, which they have dubbed the “continuum of urbanity,” helps urban ecologists, planners, and city managers better understand how these areas function and what matters most to residents. The continuum may also be useful to policy experts, engineers, decision makers, and activists.

The paper grew out of a Cary Conference in 2021 and includes four Cary coauthors: Winslow Hansen, Shannon LaDeau, Christopher Solomon, and Elizabeth Cook. Funding came from the National Science Foundation and Cary Institute’s Science Innovation Funds. 

Connections and mixtures are everywhere

Traditional thinking separates urban and rural (or ‘natural’) spaces, as well as the research fields that study them. In place of this black and white dichotomy, the new framework offers a middle ground with many shades of gray. 

The blending of urban, rural, and wild is everywhere once you know how to look for it, says Pickett. Wild animals such as coyotes and even bears sometimes turn up in towns and cities. Rural influence can be seen in community gardens or a tomato plant growing on a fire escape. There are urban influences in rural areas, too, reflected in the types of jobs people perform and the entertainment they consume.

The paper explores how these dynamics play out in the Mid-Hudson Valley as an example. This region of upstate New York is composed of small cities, towns, farms, and forests. It is physically connected to New York City by the Hudson River, several highways, railways, and more. This connectivity lets people, money, and culture flow between the two locations. For example, asylum seekers (some bused to New York City from southern states) have been housed in hotels in the Mid-Hudson Valley. The COVID-19 pandemic sent many New Yorkers into the Hudson Valley, driving up property prices and threatening to increase development on recently reforested land. The growth of online shopping, intensified by COVID-19, has changed livelihoods and locations in the Mid-Hudson Valley through novel employment opportunities, conversion of land to warehouses and large distribution centers, and the road infrastructure and associated truck traffic to serve them. In another example, the paper shares how, in suburban landscapes, connecting previously fragmented forests has facilitated the spread of blacklegged ticks and Lyme disease.

Global-scale connections can link distant places, too, such as the accidental introduction, via international trade, of forest pests like the emerald ash borer and the spotted lanternfly that are harming Hudson Valley forests. Similarly, the demand for beef in the Hudson Valley can incentivize deforestation for cattle grazing in the Amazon. And as climate change causes more droughts, floods, and fires across New York City and the Hudson Valley, it may continue to reshape the distribution of homes and businesses and the flow of ideas between the region’s urban, rural, and wild places. 

“The message of the Mid-Hudson River Valley case is that familiar urban and rural features are tightly linked,” the authors write in the paper. “One cannot be understood without the other, nor can policies, plans, and interventions neglect the entanglement of the seemingly discrete urban and rural human ecosystem characteristics.”

From theory to practice

The authors outline four main areas of life where urban, rural, and wild influence could potentially be measured:

• Livelihood: How do people in this community support themselves? People who own or work on farms, for example, will likely experience more rural influence. Urban livelihoods can become part of rural places — for example, when remote workers in the financial sector bring urban resources and expectations to seemingly rural locations.

• Lifestyle: How do people identify socially? Who do they consider part of their community? This can be linked to the kinds of houses they live in or the cars they drive, says Pickett. “If you are a farmer who owns a truck and a Mercedes, the Mercedes is something that expresses your social status and connects you with wealthy people way beyond the farm.”

• Connectivity: How are different parts of the region connected, and how well are they connected? Connectivity goes beyond physical infrastructure. For example, Pickett explains, people living on farms in South Africa may be supported by money flowing from family members working in big cities in South Africa or even the US or Europe.

• Location: The specific geography where livelihood, lifestyle, and connectivity interact.

How the continuum of urbanity can help 

“We hope that the continuum of urbanity encourages people to slow down and think before they design, build, or renovate,” says Pickett. “For example, someone might want to coordinate the traffic lights to reduce traffic and gasoline consumption. That's all well and good, but if you only design your city for efficiency, you're likely to neglect some of the amenities people need for a pleasant, healthy life. Our framework slows you down and makes you ask, ‘How's this going to affect how people live, or where they can recreate, or how they can build social relationships?’ If your profession is an urban ecologist or an urban designer, an urban planner, or a city manager, you have to be aware of all of these components.”

Coauthor and Cary ecologist Shannon LaDeau said she is already incorporating the continuum of urbanity in Defining Urban Biodiversity, a project she co-leads with Scenic Hudson that seeks to understand how changing green spaces in three Hudson Valley cities impacts plants, animals, and people. “The ideas in the paper inform how I think about the urban matrix that links our study sites to each other, to New York City, as well as to ecosystems of the Hudson River and Catskills,” she said.

Coauthor Robert Freudenberg, vice president of energy and environmental programs at the Regional Plan Association, said the Continuum of Urbanity approach is helping him move away from oversimplistic categorizations of land and community, to better consider the complex mixtures in the places where he works, especially when planning for climate change.  

“The concept provides an extraordinary framework for considering how climate impacts are manifesting within the natural systems that bind the region together,” said Freudenberg. “If we are going to plan and manage our way to adapt to climate change, and hopefully avoid its very worst impacts, understanding the ecological interactions that branch across our developed places will be essential.”

Cary’s Winslow Hansen, coauthor and director of a large collaborative that seeks to reduce the risk of catastrophic fires in the western US, says the continuum of urbanity helps him see an important part of his work in a new way. 

“In my current area of work, we think about the wildland urban interface as a distinct boundary between human communities and wild areas as the epicenter of fire risk,” says Hansen. “But if you instead embrace a continuum of urbanity, then risk mitigation from fire could become more nuanced, tailored to local ecological and social conditions rather than viewing the world as clearly categorized into one or the other.”

There remains much work to do to refine the continuum of urbanity and figure out how to measure the three dimensions. However, the authors hope that the new concept will change the way people think about communities, guiding more thoughtful research and helpful interventions. 

Funding

This publication was funded by the US National Science Foundation, the National Science Foundation of China, and the Science Innovation Funds of Cary Institute.

 

Authors

Steward T. A. Pickett - Cary Institute of Ecosystem Studies 

Weiqi Zhou - Chinese Academy of Sciences

Daniel L. Childers - Arizona State University

J. Morgan Grove - Yale School of the Environment

Winslow D. Hansen - Cary Institute of Ecosystem Studies

Dexter H. Locke - USDA Forest Service

Christopher Boone - University of Southern California

Karen C. Seto - Yale School of the Environment

Dawa Zhaxi - Chinese Academy of Sciences

Shannon LaDeau - Cary Institute of Ecosystem Studies

Leonard Nevarez - Vassar College

Robert Freudenberg - Regional Plan Association

Christopher T. Solomon - Cary Institute of Ecosystem Studies

Elizabeth M.Cook - Cary Institute of Ecosystem Studies, Barnard College

Russell Urban-Mead - LaBella Associates

David Maddox - The Nature of Cities

Adam R. Bosch - Hudson Valley Pattern for Progress

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Cary Institute of Ecosystem Studies is an independent nonprofit center for environmental research. Since 1983, our scientists have been investigating the complex interactions that govern the natural world and the impacts of climate change on these systems. Our findings lead to more effective resource management, policy actions, and environmental literacy. Staff are global experts in the ecology of:  forests, freshwater, soils, cities, and disease.

 

 

 

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Journal

npj Urban Sustainability

DOI

10.1038/s42949-026-00347-8 

Article Title

The continuum of urbanity: a synthetic concept for research on urban-rural mixtures

 

Deforestation policies are failing to protect against a potentially bigger threat to the Brazilian Amazon

University of Cambridge

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Antonio has spent the past seven years running toward fires that most others run from. A firefighter in the Brazilian Amazon since 2019, he works inside the Chico Mendes Extractive Reserve, one of the most biodiverse places on Earth.

But things are changing, and fast. “2024 was the most extreme year for fires,” Antonio said. “I had never seen anything like it. The forest burned like dry pasture – it was frightening for those of us who risk our lives to protect it.”

What Antonio and his fellow firefighters are witnessing on the ground has been backed up by a new study. An international team of researchers, led by the University of Cambridge, have found that the policies that helped reduce deforestation in the Brazilian Amazon over the past two decades have mostly failed to stop forest degradation: a slower and potentially more dangerous form of destruction. Their results are published in the Proceedings of the National Academy of Sciences.

Unlike deforestation, where whole areas of forests are cleared for farming, industry or infrastructure, a degraded forest still has trees standing. However, it has been so damaged by fire, illegal logging, fragmentation, droughts and over-hunting that it has lost much of its ecological value. The forest floor, stripped of shade and moisture, becomes a tinderbox.

“There’s still a forest there, but it’s so damaged that the carbon it once stored starts leaking, the animals have disappeared, and new grass species colonise the forest edges,” said lead author Federico Cammelli from Cambridge’s Department of Geography and the Conservation Research Institute. “Tropical forest fires are low intensity, flames often go undetected under the canopy, but after one or two years, trees die while standing, and the forest transforms into a cemetery of dead standing trees.”

Earlier research found that between 2001 and 2018, net carbon emissions from forest degradation in the Brazilian Amazon were comparable or even higher than those from deforestation itself. By 2050, degradation could affect the entire Brazilian Amazon, but it has barely featured in the policies meant to protect it.

Brazil has made real progress on deforestation. The first phase of the government’s Plan for Prevention and Control of Deforestation in the Amazon, launched in the mid-2000s, reduced tree clearing by an estimated 60 to 80 percent. Agreements in the private sector – including a moratorium on soybeans from deforested land, and a commitment from meat packers not to source cattle from newly deforested areas – also contributed to the region’s success.

However, the researchers found that four major policies meant to reduce deforestation across three Brazilian states did not reduce degradation.

When deforestation slows down, some degradation slows as well, since forests suffer less from so-called edge effects where cleared areas touch intact woodland. “However, we found no conclusive evidence that any of the supply chain policies, like the soy moratorium or the cattle agreements, tackled other big drivers of anthropogenic degradation, like fires, logging and fragmentation,” said Cammelli.

In one case, the research suggests, even successful deforestation policies can make degradation worse. The G4 cattle agreement, signed by Brazil’s four biggest meat packers, appeared to be linked to an increase in timber extraction: possibly because as cattle ranching became more regulated, some businesses switched to the less-regulated logging sector.

Back in Chico Mendes, Antonio sees some of the consequences of these gaps in policy. He said the dry season now lasts longer each year, forests are growing more fragile, and the rains arrive with sudden violence, washing out bridges and blocking roads.

He is not optimistic that the law is keeping up. “Environmental laws should be stricter, and offenders should be properly published,” he said. “If we lose the forest, we indirectly lose our lives.”

Cammelli said that political will is vital. An update to Brazilian environmental policy published in 2023 includes forest degradation among the criteria for targeting environmental law enforcement towards municipalities with poor environmental records, along requirements to reduce deforestation specifically.

“Fires often spread over many properties and entail complex liabilities: who is responsible for ignition, who for fire spread? They are best addressed at the landscape scale. The timber sector remains poorly regulated, and much can be done to crack down illegal logging,” he said.

The researchers are calling for a fundamental shift in how governments, companies and regulators think about how to best protect forests.

The EU Deforestation Regulation, which bans imports of products linked to forest destruction, defines degradation too narrowly, the researchers say, and largely overlooks the fire damage and fragmentation caused by soybean and beef production. The researchers are urging the EU to expand their definition of degradation.

Despite commitments on deforestation, the researchers found no publicly documented examples of companies operating in the Brazilian Amazon that had set concrete targets for specifically addressing forest degradation.

“Avoiding deforestation and degradation is so much more important for climate and nature than restoring what’s already gone,” said senior author Professor Rachael Garrett, also from Cambridge’s Department of Geography and Conservation Research Institute. “There are certain things you can’t get back.”

“Every year,” said Antonio, “the forest and wildlife become more vulnerable.”

The research was supported in part by the European Union and the Swiss National Science Foundation.

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Journal

Proceedings of the National Academy of Sciences

DOI

10.1073/pnas.2507793123 

Article Title

Deforestation-focused policies do not reduce degradation in the Brazilian Amazon

Article Publication Date

1-May-2026