Is it the school, or the students?

Study shows perceptions of “good” schools are heavily dependent on the preparation of the students entering them

MASSACHUSETTS INSTITUTE OF TECHNOLOGY

Are schools that feature strong test scores highly effective, or do they mostly enroll students who are already well-prepared for success? A study co-authored by MIT scholars concludes that widely disseminated school quality ratings reflect the preparation and family background of their students as much or more than a school’s contribution to learning gains. 

Indeed, the study finds that many schools that receive relatively low ratings perform better than these ratings would imply. Conventional ratings, the research makes clear, are highly correlated with race. Specifically, many published school ratings are highly positively correlated with the share of the student body that is white.

“A school’s average outcomes reflect, to some extent, the demographic mix of the population it serves,” says MIT economist Josh Angrist, a Nobel Prize winner who has long analyzed education outcomes. Angrist is co-author of a newly published paper detailing the study’s results.

The study, which examines the Denver and New York City school districts, has the potential to significantly improve the way school quality is measured. Instead of raw aggregate measures like test scores, the study uses changes in test scores and a statistical adjustment for racial composition to compute more accurate measures of the causal effects that attending a particular school has on students’ learning gains. This methodologically sophisticated research builds on the fact that Denver and New York City both assign students to schools in ways that allow the researchers to mimic the conditions of a randomized trial.

In documenting a strong correlation between currently used rating systems and race, the study finds that white and Asian students tend to attend higher-rated schools, while Black and Hispanic students tend to be clustered at lower-rated schools. 

“Simple measures of school quality, which are based on the average statistics for the school, are invariably highly correlated with race, and those measures tend to be a misleading guide of what you can expect by sending your child to that school,” Angrist says. 

The paper, “Race and the Mismeasure of School Quality,” appears in the latest issue of the American Economic Review: Insights. The authors are Angrist, the Ford Professor of Economics at MIT; Peter Hull, a professor of economics at Brown University; Parag Pathak, the Class of 1922 Professor of Economics at MIT; and Christopher Walters PhD ’13, an associate professor of economics at the University of California at Berkeley. Angrist and Pathak are both professors in the MIT Department of Economics and co-founders of MIT’s Blueprint Labs, a research group that often examines school performance.

The study uses data provided by the Denver and New York City public school districts, where 6th-graders apply for seats at certain middle schools, and the districts use a school-assignment system. In these districts, students can opt for any school in the district, but some schools are oversubscribed. In these circumstances, the district uses a random lottery number to determine who gets a seat where. 

By virtue of the lottery inside the seat-assignment algorithm, otherwise-similar sets of students randomly attend an array of different schools. This facilitates comparisons that reveal causal effects of school attendance on learning gains, as in a randomized clinical trial of the sort used in medical research. Using math and English test scores, the researchers evaluated student progress in Denver from the 2012-2013 through the 2018-2019 school years, and in New York City from the 2016-2017 through 2018-2019 school years. 

Those school-assignment systems, it happens, are mechanisms some of the researchers have helped construct, allowing them to better grasp and measure the effects of school assignment. 

“An unexpected dividend of our work designing Denver and New York City’s centralized choice systems is that we see how students are rationed from [distributed among] schools,” says Pathak. “This leads to a research design that can isolate cause and effect.”

Ultimately, the study shows that much of the school-to-school variation in raw aggregate test scores stems from the types of students at any given school. This is a case of what researchers call “selection bias.” In this case, selection bias arises from the fact that more-advantaged families tend to prefer the same sets of schools. 

“The fundamental problem here is selection bias,” Angrist says. “In the case of schools, selection bias is very consequential and a big part of American life. A lot of decision-makers, whether they’re families or policymakers, are being misled by a kind of naïve interpretation of the data.” 

Indeed, Pathak notes, the preponderance of more simplistic school ratings today (found on many popular websites) not only creates a deceptive picture of how much value schools add for students, but has a self-reinforcing effect — since well-prepared and better-off families bid up housing costs near highly-rated schools.As the scholars write in the paper, “Biased rating schemes direct households to low-minority rather than high-quality schools, while penalizing schools that improve achievement for disadvantaged groups.” 

The research team hopes their study will lead districts to examine and improve the way they measure and report on school quality. To that end, Blueprint Labs is working with the New York City Department of Education to pilot a new ratings system later this year. They also plan additional work examining the way families respond to different sorts of information about school quality.

Given that the researchers are proposing to improve ratings in what they believe is a straightforward way, by accounting for student preparation and improvement, they think more officials and districts may be interested in updating their measurement practices. 

“We’re hopeful that the simple regression adjustment we propose makes it relatively easy for school districts to use our measure in practice,” Pathak says.

The research received support from the Walton Foundation and the National Science Foundation. 

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Written by Peter Dizikes, MIT News

Paper: “Race and the mismeasure of school quality”

https://www.aeaweb.org/articles?id=10.1257/aeri.20220292

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JOURNAL

American Economic Review Insights

DOI

10.1257/aeri.20220292 

ARTICLE TITLE

“Race and the mismeasure of school quality”

 

Music: Song lyrics have become simpler and more repetitive since 1980

SCIENTIFIC REPORTS

We have been alerted to a potential error in some of the coding used by the authors in their analyses and are looking into this as a matter of urgency. The authors are confident that the main findings of the paper will remain unaltered, however some aspects may be affected and we have removed two sentences from the press release to reflect this. We will provide an update if there are further developments. We apologise for any inconvenience caused.

The lyrics of English-language songs have become simpler and more repetitive over the past 40 years, according to a study published in Scientific Reports.

Eva Zangerle and colleagues analysed the lyrics of 12,000 English-language rap, country, pop, R&B, and rock songs (2,400 songs per genre) released between 1980 and 2020. The authors found that, in general, lyrics have become simpler and easier to understand over time and that the number of different words used within songs has decreased, particularly among rap and rock songs. They suggest that general increases in the repetitiveness of lyrics across multiple genres has led to lyrics becoming simpler overall. The authors speculate that the trend towards simpler lyrics could reflect changes in music consumption, such as increases in songs being played as background music.

The authors found that lyrics have tended to become more emotional and personal over time. Use of emotionally positive and negative words increased in rap songs, while the use of emotionally negative lyrics increased for R&B, pop and country songs. Additionally, all genres showed an increase in the use of anger-related words.

Additional analyses into the views of the 12,000 song lyrics on the online song lyric platform Genius revealed that the lyrics of older rock songs tend to be viewed more than those of newer rock songs but that the lyrics of newer country songs tend to be viewed more than those of older country songs. This could indicate that rock listeners prefer lyrics from older songs, while country listeners may prefer lyrics from newer songs.

The findings provide further insight into the evolution of music over the past 40 years.

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Article details

Song lyrics have become simpler and more repetitive over the last five decades

DOI: 10.1038/s41598-024-55742-x

Corresponding Author:

Eva Zangerle
University of Innsbruck, Innsbruck, Austria
Email: eva.zangerle@uibk.ac.at

 

Please link to the article in online versions of your report (the URL will go live after the embargo ends): https://www.nature.com/articles/s41598-024-55742-x.

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JOURNAL

Scientific Reports

DOI

10.1038/s41598-024-55742-x 

ARTICLE TITLE

Song lyrics have become simpler and more repetitive over the last five decades

ARTICLE PUBLICATION DATE

28-Mar-2024

 

Building blocks for greener energy: Reconfigurable elastic metasurface akin to lego

POHANG UNIVERSITY OF SCIENCE & TECHNOLOGY (POSTECH)

 

IMAGE: 

(A) SCHEMATIC OF THE TIMOSHENKO-EHRENFEST BEAM-BASED RECONFIGURABLE ELASTIC METASURFACE (TREM) FOR MULTIFUNCTIONAL WAVE MANIPULATION (TOTAL REFLECTION, SELF-ACCELERATION, WAVE FOCUSING, AND ANOMALOUS REFRACTION). (B) IMAGE OF THE SUBSTRATE FOR THE (C) ASSEMBLY COMPONENTS DESIGNED BASED ON THE TIMOSHENKO-EHRENFEST BEAM THEORY. (D) THE ASSEMBLED TREM ON THE SUBSTRATE PLATE, WITH EACH COMPONENT CONFIGURED TO CONTROL THE INDIVIDUAL PHASE-SHIFT Ψ.

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CREDIT: POSTECH

Energy harvesting, an eco-friendly technology, extends beyond solar and wind power in generating electricity from unused or discarded energy in daily life, including vibrations generated by passing car engines or trains. Recent intriguing research has been announced, aiming to enhance the efficiency of energy harvesting using a new type of metasurface that can be reconfigured, resembling the assembly of LEGO bricks.

 

Professor Junsuk Rho from the Departments of Mechanical Engineering, Chemical Engineering, and Electrical Engineering and PhD/MS student Geon Lee from the Department of Mechanical Engineering at Pohang University of Science and Technology (POSTECH) have joined Professor Miso Kim from the School of Advanced Materials Science and Engineering at Sungkyunkwan University (SKKU) to collaborate on a research project. Together, they developed a multifunctional elastic metasurface that can be freely configured by attaching and detaching components for practical applications. This research was published in one of the international journals in materials science, Advanced Science.

 

Metamaterials are artificially designed structures that exploit the relationships among wavelengths to manipulate wave energy such as light, vibration, and sound. Harnessing this capability in energy harvesting allows for the gathering of elastic waves in piezoelectric components, thereby increasing the efficiency of electricity production. However, limitations in the theoretical analysis of the beams constituting metamaterials confine their operation to a single frequency and restrict their utility to specific purposes, posing challenges for their practical application in real structures.

 

The research team overcame these limitations by employing the Timoshenko–Ehrenfest beam theory instead of the conventional Euler-Bernoulli beam theory. What distinguishes the former is its consideration of the fundamental characteristics of elasticity, including shear deformation and rotational inertia effects of the beam. This study marks the first application of this theory to elastic metamaterial research.

 

The researchers succeeded in interpreting and modeling elastic metamaterials for phase modulation of elastic waves using the Timoshenko–Ehrenfest beam theory. Furthermore, they fabricated a new type of Timoshenko–Ehrenfest beam-based reconfigurable elastic metasurface (TREM) capable of attaching and detaching multiple structures. The TREM can reconstruct its surface depending on its application, enabling control over various wave phenomena such as anomalous wave refraction, wave focusing, self-accelerated wave propagation, and total wave reflection across a wide frequency range.

 

Notably, the team's TREM demonstrated outstanding effectiveness in harvesting elastic wave energy, enhancing the electrical output power of piezoelectric components by up to eight times. This highlights its value as a piezoelectric energy harvesting system.

 

Professor Junsuk Rho, the lead researcher, stated: “I believe that our newly developed metasurface, designed to operate across multifunctional and wide-frequency ranges, will prove invaluable in energy harvesting, most notably in the eco-friendly utilization of ambient energy. This technology, along with its applications in structural health monitoring, wireless sensing, and the Internet of Things, holds great potential for significant contributions across diverse fields.”

 

This work was supported by the N.EX.T. Impact Project of POSCO Holdings, as well as by funding from various programs including the Pioneer Research Center Program, the Regional Leading Research Center (RLRC) Program, and the Laboratory for Future Technology Program, all administered by the National Research Foundation of Korea and funded by the Ministry of Science and ICT of the Korean government.

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JOURNAL

Advanced Science

DOI

10.1002/advs.202400090 

ARTICLE TITLE

Timoshenko–Ehrenfest Beam-Based Reconfigurable Elastic Metasurfaces for Multifunctional Wave Manipulation

 

Exploring ‘sufficiency’: An overlooked strategy for protecting biodiversity?

PENSOFT PUBLISHERS

 

IMAGE: 

METHODOLOGY

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CREDIT: MARIANNE HACHTMANN

A study from the Technical University Berlin suggests ‘sufficiency’ should be a more prominent strategy for protecting biodiversity.

Published in the open-access journal Nature Conservation, the paper analyses the intersection between biodiversity conservation and sufficiency strategies aimed at reducing consumption and resource use.

Study author Marianne Hachtmann notes that despite the established connection between excessive resource use by humans and biodiversity loss, there is limited explicit focus on how sufficiency strategies can support biodiversity preservation.

Reviewing literature from 2017 to 2021 and publications by nature conservation associations, the research identifies a notable gap in discussions linking sufficiency directly with biodiversity outcomes. Possible reasons for this may be the term’s political implications, lack of descriptiveness, as well as the use of other terms.

Furthermore, the lack of connection between sufficiency and biodiversity could be because they belong to different 'scientific spheres'. Linking the two terms thus requires a reflective, interdisciplinary perspective.

The study proposes a detailed sufficiency typology to foster a systematic approach towards integrating the term in biodiversity conservation efforts.

“The sufficiency typology developed here allows for a systematic integration of sufficiency into biodiversity conservation and thus a joint consideration of social and nature conservation concerns,” says Marianne Hachtmann, Technical University Berlin.

Policymakers, conservationists, and researchers are urged to prioritise sufficiency for the broader strategy for biodiversity conservation and sustainable living. The paper calls for further investigation into how adopting sufficiency strategies can be a crucial element in conserving biodiversity and ensuring a sustainable future.

Original source

Hachtmann M (2024) Linking sufficiency and the protection of biodiversity: An issue of political implications, framing, descriptiveness and interdisciplinarity? Nature Conservation 55: 83-102. https://doi.org/10.3897/natureconservation.55.118243

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JOURNAL

Nature Conservation

DOI

10.3897/natureconservation.55.118243 

ARTICLE TITLE

Linking sufficiency and the protection of biodiversity: An issue of political implications, framing, descriptiveness and interdisciplinarity?

 

Corn reduces arsenic toxicity in soil 

UNIVERSITY OF BASEL

 

IMAGE: 

CORN PLANTS IN A FIELD EXPERIMENT NEAR LIESBERG, BASELLAND, SWITZERLAND.

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CREDIT: UNIVERSITY OF BASEL, VERONICA CAGGÌA

When crops grow in arsenic-contaminated soil, this toxic element accumulates in the food chain. A study involving the University of Basel has now discovered a mechanism used by corn plants to reduce arsenic uptake: the key factor is a special substance released into the soil by the roots.

Arsenic is a toxic metalloid of natural origin. Arsenic-contaminated soils and waters are found all over the world, especially in southeastern Asian countries like Bangladesh, Vietnam, and China. Also, Switzerland has a few natural hot spots where arsenic is found in above-average concentrations. An example is soil at Liesberg in the canton of Baselland.

“The particular problem for plants is that arsenic behaves chemically similar to phosphorus,” says Professor Klaus Schlaeppi of the Department of Environmental Sciences at the University of Basel. Phosphorus is an important nutrient that plants take up through special transport channels in their roots. “The arsenic enters the plants through these channels.” As a result, more and more of the toxic substance accumulates in the biomass and gets into the food chain. On the long run, this negatively affects human health. High arsenic exposure can cause neurological damage and cancer, for example.

Roots release an antidote
But as Schlaeppi's team has now reported in the scientific journal PNAS, corn reduces arsenic toxicity through compounds known as benzoxazinoids. These substances are produced by most plants in the botanical group of grasses, which also includes corn and wheat. Corn produces particularly large quantities of benzoxazinoids, which are also released into soil through the root system. “There was already some evidence that corn takes up less arsenic than other plant species,” says Schlaeppi.

To test this hypothesis, the researchers grew corn plants in two types of soil: without arsenic and with high levels of arsenic. They performed the same experiment in parallel using corn plants that cannot produce benzoxazinoids because of a genetic defect. Schlaeppi performed these experiments in collaboration with the research groups of Professor Adrien Mestrot and Professor Matthias Erb at the University of Bern.

Mitigating arsenic toxicity
The result was unambiguous: benzoxazinoid-producing corn grew better in the arsenic-containing soil and accumulated significantly less arsenic in its biomass than the corn that did not exude benzoxazinoids. When the researchers mixed benzoxazinoids into the arsenic-containing soil, the mutant plants were also protected from arsenic toxicity. “This provided the proof that the presence of benzoxazinoids in soil reduced arsenic uptake into plants,” says Schlaeppi.

Next, the researchers wanted to find the underlying mechanism causing this effect. Analyses of the root microbiome indicated that bacteria and fungi were not involved. However, chemical soil analyses showed that a particularly toxic form of arsenic disappeared when benzoxazinoids are present. “This indicated that the benzoxazinoids transform arsenic in such a way that it can no longer be taken up through the root.” What chemical processes are involved is currently still unclear.

Further experiments showed that the positive effect of benzoxazinoids in soil persisted for a long time: even a second generation of corn still benefited from the benzoxazinoids discharge of the first generation.

“One application of these findings would be to cultivate at arsenic-contaminated locations plant varieties that release more benzoxazinoids,” says Schlaeppi. Hyper-emitting plants could be generated through classic breeding or targeted genetic modifications. “This way we could be more certain that less arsenic is entering the food chain.”

Seedlings of corn plants in a field experiment near Liesberg. W22 denotes the plants that produce benzoxazinoids. The bx1 corn plants lack the ability to produce these substances.

CREDIT

University of Basel, Veronica Caggìa

First author Veronica Caggìa measures the chlorophyll content of maize leaves. 

These measurements provide an approximation for photosynthesis and plant health.

CREDIT

University of Basel, Antoine Baud

JOURNAL

Proceedings of the National Academy of Sciences

DOI

10.1073/pnas.2314261121 

 

How and why animals can live alongside humans

New study suggests animals can live alongside humans—if they are risk-analysis experts

MAX PLANCK INSTITUTE FOR EVOLUTIONARY ANTHROPOLOGY

 

IMAGE: 

FLOCK OF GREAT-TAILED GRACKLES ON POWERLINES.

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CREDIT: © BRIAN HENDERSEN

“For animals, living alongside humans is ‘risky business’. But some species, like grackles, are clearly coping better in human-dominated environments, even seeking them out. We wanted to find out the secret to grackles’ urban-invasion success story,” said Breen.

The research is based on new analyses of grackles’ feeding behaviour. Deffner explained: “Cities are chaotic; they may have more cafes where animals like grackles can nab food, but they’re also filled with unpredictable people and their pets. To help manage this uncertainty, we thought grackles might use a specific strategy when trying to find food.”

Across three different populations, the researchers first examined how quickly grackles learned food was hidden in one particular place over another. Next, when the location of the food was swapped, the researchers examined how quickly the grackles relearned where to find it.

Better safe than sorry when leading an urban invasion

“Our key behavioural finding is that—across all three populations—male grackles were faster than female grackles at relearning the location of an out-of-sight treat. This robust result means male grackles are more efficient foragers in uncertain environments,” said Breen.

Under uncertainty, how do male grackles ‘outlearn’ female grackles? “Unlike females, males exhibit pronounced risk-sensitive learning. That is, males pay close attention to whether they recently found food, and, if so, they pretty much stick to feeding from that location, instead of gambling on exploring another location,” explained Deffner. The researchers said they were able to infer this strategy from grackles’ feeding behaviour via cognitive modelling.

“This sex differences in grackles’ learning makes biological sense,” said Breen, adding: “In this species, males are the ones that disperse and move into new territories; in other words, they lead their species’ urban invasion. So, as urban-invasion leaders, male grackles should proceed with caution—new neighbourhoods will pose new challenges”. The authors said they thought later-arriving females could overcome these same challenges by learning from the already established, and therefore presumably ‘knowledgeable’, males.   

Risk-sensitive learners are winners in unpredictable environments

On their computers, the researchers also artificially simulated evolution, to examine the kinds of learning strategies that emerge victorious from unpredictable environments like urban environments. Deffner explained: “In this urban-like environment, pretend animals need to learn to find food. The learning strategy they use to find food determines how much they get to eat. And how much they get to eat determines whether they can have babies who also learn roughly the same way. Over many generations, then, the animals with the best learning strategy will come to dominate the urban-like environment. Importantly, these ‘winners’ will give us an idea of how animals in general can thrive in the Anthropocene”.

Which learning strategy do unpredictable urban-like environments prefer? “Strikingly, in times of uncertainty, we found risk-sensitive learners were more likely to dominate over learners with other strategies. This result implies risk-sensitive learners like male grackles are better adapted to cope in chaotic settings, human-induced or otherwise”, said Breen.

Breen concluded: “Our study offers compelling evidence for how and why at least grackles are thriving in unpredictable urban environments. We link sex differences in foraging grackles’ learning strategies to sex differences in who leads their species’ invasion, and we further link the learning strategy used by these urban-invasion leaders to likely being a generally good one for any animal navigating a life shared with humans”.

To help facilitate future similar study on human-animal coexistence, the researchers created an online repository where scientists and the public alike can freely access their custom-built modelling tools.  In reference to the repository, Deffner said: “We hope this open-science resource proves useful to others”.

Male great-tailed grackle on a power line holding a sauce packet.

CREDIT

© Gary Leavens

Male great-tailed grackle foraging in a parking lot.

CREDIT

© John Mangold

JOURNAL

eLife

DOI

10.7554/eLife.89315 

ARTICLE TITLE

Risk-sensitive learning is a winning strategy for leading an urban invasion

ARTICLE PUBLICATION DATE

2-Apr-2024

 

Older trees help to protect an endangered species

When old trees are life shelters

UNIVERSITY OF BARCELONA

 

IMAGE: 

PROFESSOR SERGI MUNNÉ-BOSCH, FROM THE FACULTY OF BIOLOGY AND THE UB BIODIVERSITY RESEARCH INSTITUTE (IRBIO).

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CREDIT: UNIVERSITY OF BARCELONA

The oldest trees in the forest help to prevent the disappearance of endangered species in the natural environment, according to a study led by the University of Barcelona. This is the case of the wolf lichen — threatened throughout Europe —, which now finds refuge in the oldest trees in the high mountains of the Pyrenees. This study reveals for the first time the decisive role of the oldest trees in the conservation of other living beings thanks to their characteristic and unique physiology.

Conserving the oldest trees in forests will be essential to protect biodiversity in forest ecosystems, which are increasingly affected by the impact of global change. This is stated on a new study published in the journal Proceedings of the National Academy of Sciences USA (PNAS). The study is signed by the experts Sergi Munné-Bosch and Ot Pasques, from the Faculty of Biology and the UB Biodiversity Research Institute (IRBio).

When old trees are life shelters

The wolf lichen (Letharia vulpina) is a species with a very limited distribution that is prevalent in mature forests and long-lived trees. Native to the American continent, it has also been found in Europe and the Iberian Peninsula, in medium and high mountain areas. Now, the authors have discovered that the presence of this lichen in the Pyrenees is associated with the longest-lived trees, specifically the black pine (Pinus uncinata).

“These old trees are found in the most isolated places, they grow on rocks with very little substrate and show unique characteristics regarding structure and composition. Specifically, the black pine can even live for more than a millennium, and its decay would be the most important factor facilitating the presence of the lichen”, says Professor Sergi Munné-Bosch.

“Paradoxically, the worse off these trees are, the more useful they are for the ecosystem (lichen conservation). In other words, the less important they might seem as individuals because of their decline, the more important they are for the whole ecosystem", says Munné-Bosch, cited as one of the world's most influential experts in the Clarivate Analytics' 2023 list.

The best habitat for the survival of the lichen L. vulpina is the oldest trees in the forest, the authors note. “In the case of centenarian and millenarian trees, the simplicity of their development, the modular growth that allows them to respond better to injury and damage, and the high tolerance to extreme conditions (water stress, extreme temperatures, etc.) are factors that explain their great longevity in the natural environment", explains Ot Pasques, an expert from the UB’s Department of Evolutionary Biology, Ecology and Environmental Sciences and IRBio.

“Trees have survival limits in extreme conditions, but they can survive with little water and nutrient resources. They are able to survive extreme conditions and live longer, thanks to modular growth and compartmentalisation of the damage that can affect them”, says Munné-Bosch. “Slow growth, which is associated with stress responses — such as the typical cold of high mountains or drought, which is increasingly frequent in the summer — also favours the longevity of these trees.

The most majestic trees, threatened by the human footprint

Longevity is one of the biological keys that would explain the unique ecological functions of trees, which make it essential to protect species and older trees in the most isolated mountain regions. “All individuals of a population are indispensable not only for their particular population and species, but for the whole global ecosystem. Everything is closely interconnected, and even the decline and death of trees plays an essential role in conserving biodiversity and ecosystems”, says Munné-Bosch.

These giants of the forest are threatened by the human footprint, especially the felling of trees. “Environmental conditions are not a problem for these trees, but unfortunately we as a species are. Only with a deep respect for nature and the life of other living beings can we preserve the extraordinary longevity of these trees. And as we have found in this study, this will also be decisive for the preservation of all biodiversity as we know it today”, the researchers conclude.

The longest-lived trees in the Pyrenees facilitate the survival of wolf lichen, a species threatened throughout Europe.

Old trees provide invaluable services to the forest ecosystem.

CREDIT

Ot Pasques - University of Barcelona

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JOURNAL

Proceedings of the National Academy of Sciences

DOI

10.1073/pnas.231786612 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Ancient trees are essential elements for high mountain forests conservation: linking the longevity of trees to their ecological function