Reindeer grazing changes plant roots in pine forests

University of Oulu, Finland

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Reindeer grazing changes the vegetation of northern pine forests below ground as well as above it. In a recent study in Finland, trees and understorey vegetation in grazed forests had nearly 30% less shallow-root biomass than those in ungrazed areas. Root structure also changed, which may affect the ability of plants to take up water and nutrients.

Changes in pine-forest root systems associated with reindeer grazing may affect forest carbon and nutrient cycling. The impacts could be significant across reindeer-grazed boreal forests worldwide, which store around one third of the Earth’s carbon, with more than half of that carbon located in soils.

The researchers collected and compared soil samples from dry pine forests in Angeli, Raja-Jooseppi and Kätkäsuvantoin Finland. The sites were either grazed by reindeer or had been fenced to exclude reindeer grazing for 50–100 years.

The study showed that reindeer grazing reduces the quantity of tree and understorey roots particularly in the uppermost 0–5 cm of soil, where most root biomass is found.

Root abundance is influenced by the quantity and composition of vegetation as well as soil temperature. In the pine forests studied, reindeer grazing had thinned the insulating lichen cover, exposing the soil to greater temperature fluctuations. In reindeer-grazed areas, winter soil temperatures were well below freezing, reaching as low as -10°C, compared with ungrazed areas, where the minimum temperature only rarely reached -5°C.

“Winter cold and frost damage in particular may help explain the reduced amount of roots in reindeer-grazed areas. Mechanical disturbance caused by reindeer, such as trampling, may also contribute to the reduction in roots,” says Postdoctoral Researcher Maria Väisänen of the Water, Energy and Environmental Engineering Research Unit at the University of Oulu, Finland.

The study also found that reindeer grazing changes roots, making them shorter, thicker and less branched. “The changes indicate reduced exploration for nutrients and water, as the roots became structurally less exploratory,” Väisänen says. The change may result either from root plasticity or from shifts in plant species composition. Reindeer grazing reduced both crowberry and lingonberry, which have thin and highly branched roots.

Roots take up nutrients and water and contribute carbon-rich root litter and root exudates to the soil. The amount, structure and location of roots in the soil play a central role in soil nutrient and carbon cycling.

In northern coniferous forests, roots are an essential pathway for transferring carbon from plants into the soil. Roots are estimated to account for 50–70% of the carbon entering the soil. Living roots release carbon compounds into the soil, which can stimulate microbial decomposition and the release of carbon into the atmosphere. Dead roots, in turn, form root litter in which carbon can be stored in the soil for long periods.

How was the study conducted?

The soil samples were divided into five-centimetre sections down to a depth of 25 cm. Fine and coarse roots were separated from the samples by washing, and their total amount was weighed. Fine roots were also classified according to root length, diameter and branching. The researchers also measured lichen-layer thickness, dwarf-shrub abundance, and soil temperature and moisture at the study sites.

The project was led by a research group at Umeå University, Sweden, and forms part of Johannes Cunow’s doctoral research. The University of Oulu, Finland participated in the project as a research partner.

The study Reindeer grazing induces spatial and functional shifts in root systems of boreal pine forests was published in August 2026, https://doi.org/10.1002/oik.12211

Read also:

Pollination Under Pressure: Grazing and Nutrient Enrichment Reshape Arctic Pollinator Communities and Interaction Networks

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Journal

Oikos

DOI

10.1002/oik.12211

Article Title

Reindeer grazing induces spatial and functional shifts in root systems of boreal pine forests

 

Barn owls are gradually changing color

University of Lausanne

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Barn owls

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Credit: © Quentin Fort

Over the past 30 years, Swiss barn owls have become more reddish-brown and more heavily spotted. By analysing the genomes of more than 3,000 birds, scientists at the University of Lausanne identified the genetic variants linked to these changes in plumage and revealed natural selection at work. Their findings, published in Nature Communications, show that evolution can happen rapidly in the wild.

From pure white to deep reddish-brown through all variations of golden brown, barn owl plumage varies remarkably from one bird to another. Some owls have only a few faint dark spots on their chest, while others display many more, much bolder markings.

Research at the University of Lausanne (Unil) has shown that these features are more than cosmetic. Plumage colour is linked to fertility and hunting strategies, and therefore to diet. White barn owls, for example, use moonlight to their advantage when attacking prey (see this news, in French). Spotting, meanwhile, is associated with immunity and the ability to cope with stress. Birds with large black spots appear to withstand certain stressful conditions, such as food shortages or parasites, more successfully.

Plumage is evolving

This diversity is not fixed. A study led by Tristan Cumer, a research fellow in the Department of Ecology and Evolution at Unil’s Faculty of Biology and Medicine, in the team of Professor Jérôme Goudet, shows that Swiss barn owls have gradually become more reddish-brown and more heavily spotted over the past 30 years. The findings were recently published in Nature Communications.

“Drawing on the exceptional volume of data collected by Alexandre Roulin and his group, who have monitored these birds of prey in the field for decades, we were able to sequence the complete genomes of more than 3,000 owls and identify the DNA variants associated with colour and spotting. This is one of the most in-depth genetic analyses ever conducted on a wild population,” says Jérôme Goudet, last author of the study, also affiliated with the SIB Swiss Institute of Bioinformatics.

The scientists pinpointed genetic regions that play a major role in the birds’ appearance. These include MC1R, a gene already known to affect pigmentation, and a region on a sex chromosome whose contribution to colour and spotting the researchers were able to clarify.

“This is one of the most in-depth genetic analyses ever conducted on a wild population.”
Prof. Jérôme Goudet, Department of Ecology and Evolution, Unil

Natural selection in action

The move towards redder, more heavily spotted plumage is not simply due to chance. By examining how genetic variants associated with colour and spotting became more or less common over time, the Unil biologists detected the effects of natural selection. “We compared the changes observed in the population with simulations in which evolution was entirely random. A genetic variant associated with reddish-brown plumage became far more common than chance alone could explain. Only simulations that included natural selection reproduced the changes we observed,” explains Tristan Cumer, first author of the paper. “Conducted in collaboration with the Swiss Ornithological Institute in Sempach, this study is one of the rare cases in which the genetic basis of recent evolution has been traced with such precision in the wild. This kind of demonstration is much harder in animals living in their natural environment than in a laboratory,” adds Jérôme Goudet.

“A genetic variant associated with reddish-brown plumage became far more common than chance alone could explain. Only simulations that included natural selection reproduced the changes we observed.”
Dr Tristan Cumer, Department of Ecology and Evolution, Unil

One essential question remains: why are barn owls becoming redder and more heavily spotted? Although the study clarifies the genetic basis of this evolution, the factors driving it have yet to be identified. Alexandre Roulin, professor in the Department of Ecology and Evolution and a co-author of the study, suggests several possibilities: “A change in prey availability may have favoured reddish-brown barn owls, which eat more voles, whereas white owls tend to feed more on wood mice. The increase in spotting could be linked to greater environmental stress. Despite the striking differences in colour between individuals, it remains extremely difficult to determine which ecological factors explain these variations.”

“We also do not know whether plumage colour is itself the trait directly favoured by natural selection,” says Jérôme Goudet. “MC1R plays a role in pigmentation, but it is part of the melanocortin system, which has also been linked to other traits, including stress responses and aggression. Selection may therefore be acting on one of these traits, with the change in the owls’ appearance simply arising as a consequence.”

A long-term collective effort

The findings are part of a research programme led by Jérôme Goudet and his team for almost a decade. Their goal is to decode the barn owl genome and establish the species as a model for studying evolution in the wild. The researchers have sequenced and assembled the species’ reference genome, reconstructed its evolutionary history across Europe and the Mediterranean, investigated genetic recombination, which reshuffles DNA from one generation to the next, and studied how mutations arise and are passed on within populations. “Research on this scale is possible because field teams, genomics specialists and members of the Faculty of Biology and Medicine’s core facilities work together,” says Professor Goudet.

The work is continuing. Computer analysis of photographs will allow the team to measure colour and spotting more precisely. The researchers also plan to use genetic data to reconstruct the plumage colour of birds that died very young and determine whether particular plumage features are associated with better chances of survival.

Understanding evolution is essential in a changing climate

Beyond the case of barn owls, the Nature Communications study reminds us that evolution does not take place only over millions of years. Major genetic changes can also occur within a few decades. In this case, 30 years, around ten generations, were enough for the effects of natural selection to become detectable. “The study carries an encouraging message: it shows that species living in the wild can evolve over a short period. This capacity for rapid adaptation could help them cope with environmental change, including climate change,” concludes Tristan Cumer.

 

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Journal

Nature Communications

DOI

10.1038/s41467-026-78632-4

Subject of Research

Animals

Article Title

Genomic bases of short-term evolution in wild barn owls revealed by long-term monitoring and population-scale sequencing

Article Publication Date

22-Oct-2026

Beyond the ice bath: How heat and cold affect recovery

University of East London

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Cold-water immersion is a popular post-workout recovery strategy, but new research suggests it may offer no greater benefit to muscle strength recovery than heat-based methods. 

The study, published in the Journal of Thermal Biology, investigated how different thermal recovery strategies affect muscle recovery following exercise-induced muscle damage. 

Researchers led by the University of East London found that while heat-based interventions altered several physiological markers associated with cellular stress and muscle repair, neither heat nor cold resulted in superior recovery of muscle strength over a 72-hour period.  

The research involved 40 healthy, physically active adults who completed an intensive exercise protocol designed to induce temporary muscle damage and delayed onset muscle soreness. 

 Participants were randomly assigned to one of four recovery strategies: 

• 30 minutes of hot-water immersion at 42°C 

• 15 minutes of cold-water immersion at 9°C 

• 30 minutes of hot-air exposure at 30°C 

• Passive recovery at room temperature 

 

Researchers then monitored changes in muscle strength, muscle soreness and a range of molecular markers associated with muscle damage and inflammation over the following 72 hours. 

Immediately following exercise, muscle strength decreased by approximately 36% across all groups. Although strength gradually recovered over the monitoring period, no statistically significant differences were observed between the four recovery strategies. 

However, the different recovery approaches produced distinct physiological responses. Participants receiving heat-based treatments showed increased expression of heat shock protein 72 (HSP72), a cellular stress protein associated with protective and repair-related processes within muscle. In addition, concentrations of creatine kinase-MM (CK-MM), a marker commonly associated with muscle damage, returned towards baseline more rapidly in the heat-based recovery groups than in the cold-water immersion group. 

These findings suggest that heat-based recovery strategies may influence some of the biological processes involved in recovery following muscle-damaging exercise. However, these physiological changes did not translate into significantly greater improvements in muscle strength or reductions in soreness during the 72-hour recovery period. 

Dr Freya Bayne, Lecturer in Sport and Exercise Science at University of East London and lead author of the study, said: 

"Cold-water immersion remains one of the most popular recovery strategies used by athletes and recreational exercisers alike. Our findings suggest that heat-based recovery methods produce different physiological responses following strenuous exercise, particularly in relation to markers associated with cellular protection and muscle repair. 

"We observed increases in heat shock protein expression and a faster return towards baseline for some markers associated with muscle damage in the heat conditions. However, it is important to recognise that these responses did not result in significantly greater recovery of muscle strength or lower levels of soreness over the following 72 hours. 

"The findings highlight the complexity of recovery and suggest that changes at a physiological level do not necessarily translate into immediate improvements in functional recovery. Further research is needed to understand whether repeated exposure to heat-based recovery strategies might produce longer-term benefits."  

The study was carried out in collaboration with researchers at London South Bank University (LSBU), Maastricht University, Univ Montpellier, CREPS Montpellier Font-Romeu and De Montfort University Dubai. 

Notes to editors  

• Dr Freya Bayne is available for interview, please contact pressoffice@uel.ac.uk to arrange.    

• The full paper is available at: https://www.sciencedirect.com/science/article/pii/S0306456526001841?via%3Dihub 

• About the University of East London: The University of East London (UEL), founded in 1898, is a careers-first university dedicated to empowering students with the skills, experience and networks they need to thrive in a changing world. With over 40,000 students from more than 160 countries, UEL places social mobility, inclusive excellence and real-world impact at the heart of its mission. Based in Stratford and the Royal Albert Dock, UEL is shaping a healthier, fairer and more sustainable future through transformative education, research and innovation. In 2026, UEL is celebrating another Year of Health, which includes launching a new Health Campus that will address health inequalities and foster innovation in the sector. For more information, visit www.uel.ac.uk.    

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Journal

Journal of Thermal Biology

DOI

10.1016/j.jtherbio.2026.104551 

 

Baby manta rays hunker down close to coasts before facing the open ocean’s dangers

Coastal areas offer young manta rays shelter and food before they travel open ocean as grown-ups, shows first study tracking manta ray movement in Central America

Frontiers

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One of the manta rays tracked in the study. 

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Credit: Jeffry Madrigal

Giant manta rays can grow up to nine meters long with a disc size of seven meters across and weigh up to 2,000 kg. This size leaves them with very few natural enemies once they reach adulthood at around eight to ten years old. But giant manta ray babies, called pups, cannot rely on their size to protect them from predators that live in the open ocean, including several species of shark and orcas. Instead, the first study to focus on giant manta ray movement in Central America has shown that pups stay in safe coastal areas where food is available until they’ve grown large enough to face the dangers of the high seas.

“We show that manta rays’ lifestyle isn’t a one-size-fits-all behavior. Giant manta rays in Central America undergo a dramatic shift in space use as they mature,” said lead author of the Frontiers in Fish Science study, Jeffry Madrigal-Mesén, a researcher and project leader of Mantas Costa Rica. “Juveniles remained strictly within shallow nearshore waters that serve as coastal refuges, but most of the tracked adults executed long-distance transboundary migrations along the continental shelf break into Central America.”

Coast to sea

The team used a variety of methods for tracking and identifying mantas at five locations between 2018 and 2025. Acoustic telemetry, which uses underwater sound pulses, let them monitor fine-scale movement of 59 individuals across coastal aggregation spots like cleaning stations. Satellite telemetry, where transmitters track movement and behavior from a distance, was used to track large-scale movements of 12 individuals. Photo ID was used to identify individual manta rays.

“If we hadn’t used all three technologies together, we simply wouldn’t have been able to piece this puzzle together,” explained Madrigal-Mesén. “Combining these tools turned fragmented data into a unified, undeniable story.”

The combined dataset of more than 12,000 detections showed that young mantas – those with disc widths of around three meters or less – stick to shallow coastal refuges. These coastal waters provide pups with a safe place that doesn’t overlap with predators’ hunting grounds. There they can also find plenty of food and hiding spots, and rely on essential services provided by reefs, such as cleaning.

“Mature adults can rely on their massive body size and their ability to dive deep to evade threats. But juveniles don't have that luxury,” said Madrigal-Mesén. “What is truly amazing is seeing how strictly young manta rays stick to coastal waters as long-term refuges. We see the same individuals more often than once a year. In fact, just recently, they were sighted again at the exact same tagging location,” continued Madrigal-Mesén. “It is always a joy to see them again – they have truly become a part of the family.”

In contrast to the coast-loving pups, nine mature mantas went on expansive migrations along the continental shelf break. The movement of one manta ray, nicknamed Mickey Mouse because of a spot pattern on his belly, also suggested that mantas continue to display high site-fidelity once grown-up. Unusually approachable, Mickey Mouse allowed scientists to perform tagging multiple times over several years, which provided a continuous dataset. In 2020, he logged 462 acoustic detections at the coastal hub El Secreto. Three years later he returned to the same shelf and stayed there for 38 days.

“Nearshore cleaning stations transcend basic hygienic function; they act as primary social hubs where courtship and reproductive interactions take place,” explained Madrigal-Mesén. “Returning to a predictable coastal depot allows mature rays to prioritize social and cleaning needs before undertaking large-scale regional migrations.”

Protected manta highways

Adults, however, face different dangers when they leave coastal regions — which are often protected marine reserves — for the open ocean.

“As soon as these rays move beyond isolated marine reserves, their legal protection drops to zero. This exposes them to unselective industrial fisheries and vessel strikes as they navigate unprotected international corridors,” said Madrigal-Mesén.

This shows that marine protected areas alone are not enough to protect highly mobile species moving across Central America, the authors say. What is needed are multi-national ‘conservation swimways’ that link domestic juvenile coastal refuges with adult migratory corridors.

“This study opens a new chapter for manta ray research in Central America,” Madrigal-Mesén concluded. “We hope it sparks fresh enthusiasm and encourages future collaborators to join us in executing the new ideas and research projects we have planned for the conservation of this species.”

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Journal

Frontiers in Fish Science

DOI

10.3389/frish.2026.1916489

Method of Research

Experimental study

Subject of Research

Animals

Article Title

Bridging coastal aggregation hubs and oceanic sanctuaries: The first multi-scale telemetry baseline for the giant manta ray (Mobula birostris) in Central America

Article Publication Date

22-Oct-2026

Puntitos, one of the immature mantas the scientists followed. Credit: Jeffry Madrigal.

Immature manta ray equipped with satellite tag. 

Manta ray in close proximity to a diver. 

Credit

Jeffry Madrigal

 

Study finds humpback whales growing faster than expected

Griffith University

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The study's findings suggested eastern Australian humpback whales grew faster than other humpback whale populations studied elsewhere in the world.

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Credit: Pacific Whale Foundation

Eastern Australian humpback whales reach nearly their full adult size remarkably quickly, a new Griffith University-led study has found, as shown by the first contemporary growth curves for this recovering whale population.

Published in Marine Mammal Science, the study combined drone-based aerial measurements with long-term photo-identification records to track growth across hundreds of whales ranging from newborn calves to adults more than 40 years old.

The research, led by Griffith University PhD Candidate Stephanie Stack in collaboration with the Pacific Whale Foundation in Hervey Bay, found eastern Australian humpback whales reached approximately 10.9m in length by the age of five and attained 90 per cent of their adult body length by about six to seven years of age.

Ms Stack said the findings suggested eastern Australian humpback whales grew faster than other humpback whale populations studied elsewhere in the world.

"This is faster growth than other humpback whale populations that have been measured," she said.

"These are also the first contemporary growth curves developed for eastern Australian humpback whales using measurements from living animals, updating knowledge that has relied heavily on measurements collected during the commercial whaling era in the mid-20th century.

"These new growth curves establish a baseline for investigating how whale biology may respond to changing environmental conditions."

Researchers collected measurements from 865 individually identified whales between 2021 and 2024 using non-invasive drone photogrammetry.

The dataset included calves, juveniles and adults, allowing growth during the important early years of life to be measured directly rather than inferred from older animals.

The study found growth was most rapid during early life before gradually slowing as whales approached their maximum adult size.

The new results aligned with historical estimates of adult body size from Australia, suggesting humpback whales have maintained similar adult lengths despite decades of population recovery and environmental change.

Eastern Australian humpback whales are recognised as one of the world's most successful whale conservation stories, having recovered dramatically since the end of commercial whaling.

"Understanding how quickly whales grow provides another piece of the puzzle in understanding the biology of this recovering population," Ms Stack said.

"Growth influences many aspects of a whale's life, including its health, energy requirements and potentially the timing of reproduction."

Ms Stack added the new growth curves provided an important benchmark for future monitoring of whale populations, and helped scientists investigate how humpbacks responded to changing ocean conditions.

"As environmental conditions continue to change, having robust biological benchmarks like these will be essential for understanding how whale populations are responding," she said.

Ms Stack’s PhD research formed an important contribution to long-term monitoring of Southern Hemisphere humpback whales under the Humpback Whale Sentinel Programme.

The study 'Contemporary growth curves for individual humpback whales in eastern Australia using aerial photogrammetry' has been published in Marine Mammal Science.

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Journal

Marine Mammal Science

DOI

10.1111/mms.70296