Study of adolescents shows that the urban environment influences their sense of justice and trust in institutions

Over the course of three years, researchers from the University of São Paulo and their collaborators examined the “belief in a just world” of 659 São Paulo residents between the ages of 12 and 14

Fundação de Amparo à Pesquisa do Estado de São Paulo

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A study of young people in the city of São Paulo, Brazil, reveals that adolescents living in neighborhoods with high rates of violence and poor infrastructure tend to perceive the world as being more unfair for them than for others.

The Center for the Study of Violence (NEV), one of FAPESP’s Research, Innovation, and Dissemination Centers (RIDCs), analyzed the trajectories of “belief in a just world” (BJW) among 659 adolescents aged 12 to 14 over three years. The results were published in an article in the Journal of Environmental Psychology.

The concept of BJW refers to the perception that the world is generally a fair place where people “reap what they sow.” This belief is considered fundamental to forming expectations, engaging socially, and internalizing norms and values. However, according to the authors of the article, these beliefs do not develop in a vacuum; rather, they are shaped by concrete experiences in physical and social environments.

“Our hypothesis was that the physical environment, by itself, plays an important role in shaping adolescents’ beliefs about justice, regardless of relational factors such as being around parents, teachers, or law enforcement officials,” says psychologist André Vilela Komatsu, the first author of the study and a FAPESP fellow (projects 19/09360-6 and 22/07075-5).

The co-author is Simone Kühn, a neuroscientist, professor at the University of Hamburg in Germany, and director of the Center for Environmental Neuroscience at the Max Planck Institute for Human Development in Berlin. Komatsu completed his postdoctoral internship at the institute, where the study was developed in partnership.

The researchers observed that adolescents in neighborhoods marked by neglect, insecurity, and violence not only have lower levels of personal BJW, but also gradually depart from this belief over time. The feeling that one’s own life is not governed by justice can have significant implications for both psychological well-being and behavior, affecting aspects such as motivation, self-esteem, and trust in institutions.

In more affluent neighborhoods, young people have a higher personal BJW, though they do not necessarily believe that the world is generally fair. “Even upper-middle-class adolescents perceive social injustice around them,” Komatsu points out. “But because they live in more protected environments with access to services and opportunities, they feel less vulnerable and maintain a certain confidence that at least their lives will be fair.”

The study reinforces the importance of considering urban and structural factors, such as infrastructure, access to services, and community cohesion, in the debate on citizenship and democratic development. “Degraded environments not only affect physical and mental well-being but also erode trust in institutions and principles of equity,” says Komatsu.

According to the researcher, schools have the potential to play a central role in shaping how kids and teens perceive what is fair or unfair in the world around them. “The school environment is the institutional space where young people spend most of their time and continuously interact. In unequal urban areas, schools can promote an experience of citizenship that contrasts with perceived injustices in the neighborhood, transportation, or public safety. On the other hand, when schools reproduce inequalities or punitive and arbitrary practices, they reinforce the perception that institutions are unfair. In our study, we took into account how adolescents perceived their teachers in relation to the fair application of rules, that is, whether they acted with clarity, impartiality, and respect. We know from previous studies that this directly influences the formation of a sense of justice in young people.”

The study in question did not consider differences in “belief in a just world” based on gender or race. However, previous studies with the same sample revealed these differences. “These studies revealed that young people with greater social privilege – especially those who identify as white, male, from private schools, and from higher-income families – tend to have a higher personal BJW. In other words, they believe that they live in a world that’s fairer for them than for others. Of course, these differences do not only reflect individual perceptions, but also the structural inequalities present in Brazilian society,” says Komatsu.

Social media plays a significant role in shaping beliefs and values. “It’s important to note that the dissemination of content on social media occurs within ecosystems mediated by algorithms, which tend to amplify content with a high potential for emotional engagement, often simplified, sensationalized, or ideologically biased. These algorithms not only select what’s shown but also shape how events are interpreted, reinforcing perception bubbles and confirming prior beliefs. On many pages and profiles, the structural causes of social, racial, and territorial injustices are hidden or distorted and replaced by populist and simplistic narratives. This algorithmic functioning tends to lead people to interpret social injustice as the result of individual behavior or the behavior of specific groups, thereby reinforcing existing stigmas,” Komatsu emphasizes.

In this sense, although social media has the potential to foster awareness and social criticism, its algorithms tend to favor sensationalist or emotionally charged content over more balanced and well-founded information, such as that produced by scientists or institutions committed to social justice. “This not only distorts public debate but also hinders adolescents’ access to more contextualized and evidence-based interpretations of the causes of the inequalities and injustices that affect them,” the researcher argues.

The study points out that urban interventions have the potential to restore a sense of justice among adolescents in vulnerable areas if they address the everyday experiences of these young people. “Actions such as the redevelopment of public spaces – squares, cultural centers, and sports and leisure areas – symbolically convey the message that that community matters and is worthy of care. But it’s important that these initiatives be accompanied by participatory processes that foster a sense of belonging and agency, and promote the recognition of adolescents as holders of rights. In addition, continued investment in basic infrastructure, such as lighting, sanitation, transportation, and health, communicates the idea of material value for lives that are often neglected," Komatsu emphasizes.

The article “The effect of the physical environment on adolescents’ sense of justice” is available at: www.sciencedirect.com/science/article/abs/pii/S0272494425000659.

About São Paulo Research Foundation (FAPESP)
The São Paulo Research Foundation (FAPESP) is a public institution with the mission of supporting scientific research in all fields of knowledge by awarding scholarships, fellowships and grants to investigators linked with higher education and research institutions in the State of São Paulo, Brazil. FAPESP is aware that the very best research can only be done by working with the best researchers internationally. Therefore, it has established partnerships with funding agencies, higher education, private companies, and research organizations in other countries known for the quality of their research and has been encouraging scientists funded by its grants to further develop their international collaboration. You can learn more about FAPESP at www.fapesp.br/en and visit FAPESP news agency at www.agencia.fapesp.br/en to keep updated with the latest scientific breakthroughs FAPESP helps achieve through its many programs, awards and research centers. You may also subscribe to FAPESP news agency at http://agencia.fapesp.br/subscribe.

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Journal

Journal of Environmental Psychology

DOI

10.1016/j.jenvp.2025.102582 

Article Title

The effect of the physical environment on adolescents’ sense of justice

 

Evolution made us cheats, now free-riders run the world and we need to change, new book warns

University of Cambridge

 

To save democracy and solve the world's biggest challenges, we need to get better at spotting and exposing people who exploit human cooperation for personal gain, argues Cambridge social scientist Dr Jonathan Goodman.

 

In Invisible Rivals, published by Yale University Press today, Dr Goodman argues that throughout human history we have tried to rid our social groups of free-riders, people who take from others without giving anything back. But instead of eliminating free-riders, human evolution has just made them better at hiding their deception.

Goodman explains that humans have evolved to use language to disguise selfish acts and exploit our cooperative systems. He links this ‘invisible rivalry’ to the collapse of trust and consequent success of political strongmen today.

Goodman says: “We see this happening today, as evidenced by the rise of the Julius Caesar of our time—Donald Trump— but it is a situation that evolution has predicted since the origins of life and later, language, and which will only change form again even if the current crises are overcome.”

Goodman argues that over the course of human evolution “When we rid ourselves of ancient, dominant alphas, we traded overt selfishness for something perhaps even darker: the ability to move through society while planning and coordinating.”

“As much as we evolved to use language effectively to work together, to overthrow those brutish and nasty dominants that pervaded ancient society, we also (and do) use language to create opportunities that benefit us … We use language to keep our plans invisible. Humans, more than other known organisms, can cooperate until we imagine a way to compete, exploit, or coerce, and almost always rely on language to do so.”

Goodman, an expert on human social evolution at the University of Cambridge, identifies free-riding behaviour in everything from benefits cheating and tax evasion, to countries dodging action on climate change, and the actions of business leaders and politicians.

Goodman warns that “We can’t stop people free-riding, it’s part of our nature, the incurable syndrome… Free riders are among us at every level of society and pretending otherwise can make our own goals unrealistic, and worse, appear hopeless. But if we accept that we all have this ancient flaw, this ability to deceive ourselves and others, we can design policies around that and change our societies for the better.”

 

Lessons from our ancestors

Goodman points out that humans evolved in small groups meaning that over many generations we managed to design social norms to govern the distribution of food, water and other vital resources.

“People vied for power but these social norms helped to maintain a trend toward equality, balancing out our more selfish dispositions. Nevertheless, the free-rider problem persisted and using language we got better at hiding our cheating.”

One academic camp has argued that ancient humans used language to work together to overthrow and eject “brutish dominants”. The opposing view claims that this never happened and that humans are inherently selfish and tribal. Goodman rejects both extremes.

“If we accept the view that humans are fundamentally cooperative, we risk trusting blindly. If we believe everyone is selfish, we won’t trust anyone. We need to be realistic about human nature. We’re a bit of both so we need to learn how to place our trust discerningly.”

Goodman points out that our distant ancestors benefitted from risk-pooling systems, whereby all group members contributed labour and shared resources, but this only worked because it is difficult to hide tangible assets such as tools and food. While some hunter-gatherer societies continue to rely on these systems, they are ineffective in most modern societies in our globalized economy.

“Today most of us rely largely on intangible assets for monetary exchange so people can easily hide resources, misrepresent their means and invalidate the effectiveness of social norms around risk pooling,” Goodman says.

“We are flawed animals capable of deception, cruelty, and selfishness. The truth is hard to live with but confronting it through honest reflection about our evolutionary past gives us the tools to teach ourselves and others about how we can improve the future.”

 

Taking action: self-knowledge, education & policy

Goodman, who teaches students at Cambridge about the evolution of cooperation, argues that we reward liars from a young age and that this reinforces bad behaviour into adulthood.

“People tell children that cheaters don’t prosper, but in fact cheats who don’t get caught can do very well for themselves.”

“Evolutionarily speaking, appearing trustworthy but being selfish can be more beneficial to the individual. We need to recognise that and make a moral choice about whether we try to use people or to work with them.”

At the same time, Goodman thinks we need to arm ourselves intellectually with the power to tell who is credible and who is not. “Our most important tool for doing this is education,” he says. “We must teach people to think ethically for themselves, and to give them the tools to do so.”

But Goodman cautions that even the tools we use to expose exploiters are open to exploitation: “Think about how people across the political sphere accuse others of virtue signalling or abusing a well-intentioned political movement for their own gain.”

Goodman believes that exposing free-riders is more beneficial than punishment. “Loss of social capital through reputation is an important motivator for anyone,” he argues, suggesting that journalistic work exposing exploitation can be as effective at driving behaviour change as criminal punishment.

“The dilemma each of us faces now is whether to confront invisible rivalry or to let exploiters undermine society until democracy in the free world unravels—and the freedom of dissent is gone.”

Dr Jonathan R Goodman is a research associate at Cambridge Public Health and a social scientist at the Wellcome Sanger Institute.

Invisible Rivals: How We Evolved to Compete in a Cooperative World is published by Yale University Press on 17 June 2025 (ISBN: 9780300274356)

 

Medicaid cuts in the "One Big Beautiful Bill Act" could undermine the coverage, financial well-being, medical care, and health of low-income Americans, and lead to more than 16,500 medically-preventable deaths

American College of Physicians

    
Below please find summaries of new articles that will be published in the next issue of Annals of Internal Medicine. The summaries are not intended to substitute for the full articles as a source of information. This information is under strict embargo and by taking it into possession, media representatives are committing to the terms of the embargo not only on their own behalf, but also on behalf of the organization they represent.   
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1. Medicaid cuts in the "One Big Beautiful Bill Act" could undermine the coverage, financial well-being, medical care, and health of low-income Americans, and lead to more than 16,500 medically-preventable deaths

Abstract: https://www.acpjournals.org/doi/10.7326/ANNALS-25-00716

URL goes live when the embargo lifts             

A new study published in Annals of Internal Medicine estimates the potential effects on Medicaid enrollment, uninsurance, financial strain, health care access, and health outcomes from potential Medicaid budget cuts being considered in Congress, including the House reconciliation bill advanced in May. Adam Gaffney, MD, MPH and colleagues identified six potential Medicaid cuts that the House of Representatives’ Budget Committee estimates would each reduce the Federal government’s Medicaid outlays by at least $100 billion over ten years: reduction of the Medicaid matching floor; reduced funding of the ACA Medicaid Expansion; Medicaid per capita caps; Medicaid work requirements; reduced Medicaid provider taxes; and repeal of the Biden-era Medicaid eligibility rule. They also assessed the overall effects of the current House bill, which includes three of the six options along with multiple smaller policy changes, such as shortening the duration of Medicaid’s retroactive coverage and increasing cost-sharing for some Medicaid enrollees. The researchers project that individually, these six Medicaid cuts would lead to an annual increase of between 651 and 12,626 medically preventable deaths. These cuts would increase the number of uninsured by between 600,000 and 3,900,000, and the annual number of persons foregoing needed medical care by 129,060 to 838,890. If the current House bill is enacted, the number of uninsured would rise by 7.6 million. It could lead to 1.9 million people losing their personal doctor, 1.3 million foregoing needed medications, 380,270 women going without a mammogram, and 16,642 preventable deaths. The authors warn that although these cuts are intended to offset tax cuts, they would also strip care from millions of low-income Americans and possibly lead to thousands of medically preventable deaths. They assert that policy makers should weigh the likely health and financial harms to patients and providers of reducing Medicaid expenditures against the desirability of tax reductions, which would benefit mostly wealthy Americans.   

 

Media contacts: For an embargoed PDF, please contact Gabby Macrina at gmacrina@acponline.org. To contact corresponding author Adam Gaffney, MD, MPH, please email agaffney@challiance.org.      

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2. Semaglutide more effective at lowering risk for stroke and other cardiovascular outcomes compared to empagliflozin

Abstract: https://www.acpjournals.org/doi/10.7326/ANNALS-24-00775

Summary for Patients: https://www.acpjournals.org/doi/10.7326/ANNALS-24-00775-PS

URL goes live when the embargo lifts             

Two target trial emulation studies compared mortality and cardiovascular risks in adult patients treated with semaglutide or dulaglutide versus empagliflozin. The study found that semaglutide moderately lowers risk for death, myocardial infarction (MI), and stroke compared to empagliflozin; however, dulaglutide does not have a clinical treatment advantage over empagliflozin. The results are published in Annals of Internal Medicine.

 

Researchers from the University of Pittsburgh studied data from a retrospective observational cohort of patients 45 years or older with type 2 diabetes, comorbid conditions and a prescription for semaglutide, dulaglutide, or empagliflozin between 1 January 2019 and 31 December 2024. The researchers emulated two target trials of initial treatment with either semaglutide (primary trial) or dulaglutide (secondary trial) versus empagliflozin. The primary outcome was risk for the composite outcome of death, MI, or stroke. Secondary outcomes included all-cause death, MI, stroke, heart failure (HF), and atrial fibrillation. The researchers matched empagliflozin-treated patients to either semaglutide- or dulaglutide-treated patients using propensity score (PS) methods. In the primary trial analysis, 7,899 patients treated with semaglutide were matched to 7,899 patients treated with empagliflozin, with all patients having similar baseline characteristics except a higher body mass index among patients treated with semaglutide. In the secondary trial, 6093 patients treated with dulaglutide were matched with 6,093 patients treated with empagliflozin and baseline characteristics were similar. The researchers found a nominally lower cumulative incidence of death, MI, or stroke in patients using semaglutide versus empagliflozin starting at one-year of follow-up. This was largely driven by a clear lower risk of stroke when using semaglutide versus empagliflozin. All risk estimates favored the use of semaglutide versus empagliflozin for secondary outcomes. In a subgroup analysis, patients younger than 65 years and those with an HbA1C below 7% had a lower risk for death, MI, or stroke when using semaglutide. In the secondary trial, the risk for death, MI, or stroke over follow-up was similar for patients treated with dulaglutide versus empagliflozin.  

 

Media contacts: For an embargoed PDF, please contact Gabby Macrina at gmacrina@acponline.org. To contact corresponding author Anum Saeed, MD, please email Allison Hydzik at hydzikam@upmc.edu.   

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3. Phase 3 trial suggests fecal transplant is as effective as antibiotics for treating c. diff infection

Abstract: https://www.acpjournals.org/doi/10.7326/ANNALS-24-03285

Editorial: https://www.acpjournals.org/doi/10.7326/ANNALS-25-01868

URL goes live when the embargo lifts             

A phase 3 randomized controlled trial evaluated the efficacy and safety of fecal microbiota transplantation (FMT) versus the antibiotic vancomycin for adult patients with primary Clostridioides difficile infection (CDI). The trial found that FMT showed a 5.4% numerical superiority to vancomycin, indicating that it is noninferior to vancomycin. Given the potential for side effects with vancomycin, the study results suggest that FMT could be considered as a first-line treatment for primary CDI, representing a change to current practice. The results are published in Annals of Internal Medicine. 

 

The current recommended therapy for primary CDI is antibiotic treatment; however, some patients experience antibiotic-associated colitis due to CDI. Researchers from the University of Oslo and colleagues conducted a randomized, open-label, noninferiority, multi-center trial at hospitals and primary care facilities in Norway between 1 June 2019 to 15 March 2024 to determine whether FMT without antibiotic pretreatment is an effective and safe treatment for CDI. Eligible patients were 18 years or older, had primary CDI, a positive stool test result for toxin-producing C difficile, and no diagnosis of CDI in the year prior to enrollment. 104 eligible patients were randomly assigned in a 1:1 ratio to either one FMT enema administered within 24 hours of randomization or standard-of-care treatment with 125 mg of oral vancomycin four times daily for 10 days. The primary end point was clinical cure at day 14 after the start of treatment with only the assigned treatment and no recurrent CDI in the 60 days after the start of treatment. The researchers found that 66.7% of patients in the FMT group and 61.2% of patients in the vancomycin group achieved the primary end point. Subgroup analyses did not show significant differences by sex, age or CDI severity. There were no significant differences in adverse events between treatment groups.

 

Media contacts: For an embargoed PDF, please contact Gabby Macrina at gmacrina@acponline.org. To contact corresponding author Frederik Emil Juul, MD, PhD, please email f.e.juul@medisin.uio.no.

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4. Screening for anal cancer most cost-effective when initiated at age 35

Abstract: https://www.acpjournals.org/doi/10.7326/ANNALS-24-01426

URL goes live when the embargo lifts             

A microsimulation model was used to perform a benefits, harms and cost-effectiveness analysis of different anal cancer screening strategies among men who have sex with men (MSM) with HIV—individuals with 45-fold greater anal cancer risk than men without HIV. The researchers found that anal cancer screening among MSM with HIV aged 35 years or older could reduce anal cancer mortality by up to 65% and is cost-effective, with cost-effectiveness and harm-to-benefit ratios varying across a range of intervals and approaches. The results suggest value-based prioritization of anal cancer screening is needed to optimize screening use. The study is published in Annals of Internal Medicine. 

 

Researchers from the Medical University of South Carolina Hollings Cancer Center and colleagues developed a microsimulation model to simulate the life course of MSM with HIV using data from the ANCHOR (Anal Cancer–HSIL Outcomes Research) trial and other published literature. The researchers conducted the study to address the significant knowledge gap of data on long-term clinical outcomes and cost-effectiveness of screening for anal cancer. The model examined age-based anal cancer screening strategies among MSM with HIV aged 35 years or older in 2019 in the base-case analysis. Tests for primary screening and triage included anal cytology, hrHPV testing and cytology, and HPV co-testing. The researchers used the model to compare 52 different screening strategies which considered screening of persons aged 35 years or older, 40 years or older, or 45 years or older and annual, biennial, triennial, or quadrennial screening intervals. The researchers found that compared with no screening, cytology screening among MSM with HIV aged 35 years and older could reduce anal cancer mortality by up to 65%, with the greatest reductions seen in those initiating screening at an earlier age and more frequent rescreening intervals. These findings were consistent in the harm-to-benefit analysis. In the comparative analysis, anal cancer mortality reduction ranged from 25.8% for quadrennial cytology with HPV16 triage to 63.1% for annual cytology with hrHPV co-testing. HPV-based screening, specifically triennial testing for HPV16/18, was the most efficient. Cost effectiveness improved among newly eligible 35-year-olds, with biennial cytology screening being the most cost-effective. The researchers conclude that screening MSM with HIV aged 35 years or older using cytology provides greater value than initiating screening among those aged 40 or 45 years or older, in line with clinical guidelines recommending screening to start at 35. 

 

Media contacts: For an embargoed PDF, please contact Gabby Macrina at gmacrina@acponline.org. To contact corresponding author Ashish A. Deshmukh, PhD, MPH, please email Leslie Cantu at cantul@musc.edu.    

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Journal

Annals of Internal Medicine

DOI

10.7326/ANNALS-25-00716 

Method of Research

News article

Subject of Research

People

Article Title

Projected Effects of Proposed Cuts in Federal Medicaid Expenditures on Medicaid Enrollment, Uninsurance, Healthcare and Health

Article Publication Date

17-Jun-2025

CANADA

More family doctors near retirement, raising concern about future of primary care

Institute for Clinical Evaluative Sciences

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Kingston, ON, June 16, 2025 – A new ICES study has found that 1.74 million patients in Ontario are attached to family physicians aged 65 or older, and that many of those patients are elderly and have complex medical needs. 

The study, published in Canadian Family Physician, explored key trends in the characteristics of comprehensive family physicians (FPs)—those providing care for a broad range of ages and health needs—and the patients attached to them. 

The researchers found that for the first time, there was no growth of the comprehensive FP workforce, and an overall decline in the number of early career physicians (under 35 years old.) 

“A major challenge Ontario faces is an aging family physician workforce that is nearing retirement. Although we found family physicians are practicing longer than expected – into their 70s, in fact – as these physicians retire, the number of patients without a family doctor will increase, especially as fewer early career physicians are choosing family medicine,” says Dr. Kamila Premji, a family physician, ICES fellow, assistant professor in family medicine at the University of Ottawa, and PhD candidate in family medicine at Western University’s Schulich School of Medicine & Dentistry. 

A primary care system in flux 

The study included over 11 million Ontario patients as of March 2022, and 9,375 comprehensive FPs. This was an updated analysis of similar cohorts from 2008, 2013, and 2019. 

Along with a decline in the overall growth of the FP workforce and greater proportion at retirement age, the findings also showed that females made up the majority of the comprehensive workforce. Overall, a declining proportion of FPs are practicing comprehensiveness, from 77% in 2008 to 65% in 2022. 

A recent study by some of the same researchers showed that many FPs are choosing to work in hospitals instead of practicing comprehensive family medicine. 

"The data helps us to better understand the shortages we are facing, and informs strategies like team-based care, which can better support family physicians who provide comprehensive care and can reduce burnout,” says Premji.  

Compared to the overall FP workforce, the authors found that near-retirement FPs were caring for a higher proportion of patients aged 65 or older, and many with chronic obstructive pulmonary disease, congestive heart failure, diabetes, and frailty. 

“Looking to the future, we are concerned that the primary care system may not be able to absorb these medically complex patients who are attached to retiring family physicians, which will only exacerbate the current crisis,” says senior author Dr. Bridget Ryan, adjunct scientist at ICES and an associate professor at Western's Schulich School of Medicine & Dentistry. 
 
FOR FURTHER INFORMATION PLEASE CONTACT:  

Misty Pratt 
Senior Communications Associate, ICES 
Media@ices.on.ca  
343-961-6982 

 

ICES is an independent, not-for-profit research and analytics institute that uses population-based health information to produce knowledge on a broad range of healthcare issues. ICES leads cutting-edge studies and analyses evaluating healthcare policy, delivery, and population outcomes. Our knowledge is highly regarded in Canada and abroad and is widely used by government, hospitals, planners, and practitioners to make decisions about healthcare delivery and to develop policy. For the latest ICES news, follow us on BlueSky and LinkedIn: @ICESOntario 

The University of Ottawa is home to over 50,000 students, faculty and staff, who live, work and study in both French and English. Our campus is a crossroads of cultures and ideas, where bold minds come together to inspire game-changing ideas. We are one of Canada’s top 10 research universities—our professors and researchers explore new approaches to today’s challenges. One of a handful of Canadian universities ranked among the top 200 in the world, we attract exceptional thinkers and welcome diverse perspectives from across the globe. www.uottawa.ca 
 
ABOUT WESTERN 
Western University delivers an academic experience second to none. Since 1878, The Western Experience has combined academic excellence with life-long opportunities for intellectual, social and cultural growth in order to better serve our communities. Our research excellence expands knowledge and drives discovery with real-world application. Western attracts individuals with a broad worldview, seeking to study, influence and lead in the international community.  

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Journal

Canadian Family Physician

DOI

10.46747/cfp.7106406 

Method of Research

Observational study

Subject of Research

People

Article Title

Trends colliding: Aging comprehensive family physicians and the growing complexity of their patients

Article Publication Date

16-Jun-2025

 

Long-term study reveals Native seeding controls annual, but not perennial, invasive plants in sand grassland restoration

Hun-Ren Ökológiai Kutatóközpont

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image: 

Monitoring arrangement for estimating invasive propagule pressure with transect method. Established eight 100-meter-long transects towards the eight cardinal directions and recorded the number of shoots of each invasive species in 1 m x 1 m adjacent plots along each transect.

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Credit: Photo: Melinda Halassy

The HUN-REN, CER-IEB Restoration Ecology Research Group monitored vegetation changes over 17-25 years across eight restoration sites, subject to different restoration interventions: seeding with native species, mowing, and carbon amendment. The goal was to understand how these treatments influence the abundance of annual and perennial invasive alien plants over time, and how abundance of invasive species in a 100 m buffer affects invasion dynamics at restoration sites.

The results were promising for annual invaders. In most cases, their cover declined over time, especially when native seeding was applied. Seeding proved to be the most effective treatment in suppressing these fast-spreading, short-lived species. However, the picture was different for perennial invaders. These species continued to increase in cover over the decades, regardless of which restoration techniques were applied or the abundance of invasive species within a 100-meter radius of the sites.

Surprisingly, the study found that immediate local invasion pressure had little explanatory power—suggesting that broader landscape-scale processes and long-distance dispersal may play a more important role in shaping invasion outcomes. Mowing, although often used in restoration to control shrub, weeds or invasive species, was found to potentially facilitate the establishment of invasives by opening "colonisation windows" for opportunistic species already present in the landscape.

The authors emphasize that current restoration approaches are not enough to address the long-term threat posed by perennial invaders. Once established, these species are notoriously difficult to eradicate, and their increasing dominance can undermine biodiversity and the success of ecological restoration. This highlights an urgent need for more proactive, species-specific strategies that address the life history traits and dispersal mechanisms of problematic perennials.

Ultimately, the study calls for a shift in restoration planning—from a site-based perspective to a more integrated, landscape-level approach. Effective grassland restoration must consider not only what happens within the target area, but also the broader ecological context: the availability of native and invasive propagules, the disturbance regime, and the long-term resilience of native communities.

Sand grassland patch restored by seeding four native species: Festuca vaginata, Koeleria glauca, Euphorbia segueriana and Dianthus serotinus.

Credit

Photo: Melinda Halassy

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Journal

Biological Invasions

DOI

10.1007/s10530-025-03613-5 

Method of Research

Case study

Subject of Research

Not applicable

Article Title

Restorative seeding controls annual invasive species, but perennials can thrive in the long term despite treatments in sand grassland restoration

Article Publication Date

15-Jun-2025