Deer slow down forest diversity – even in the light

University of Würzburg

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In the current issue of the Journal of Applied Ecology, researchers from Julius-Maximilians-Universität Würzburg (JMU) report that roe deer restrict the natural regeneration of deciduous forests far more than previously assumed. The team led by Professor Jörg Müller demonstrated in a multi-year field experiment that even when large amounts of light enter the forest after disturbances, this advantage cannot compensate for the selective browsing by deer. 

Browsing Overrides the Positive Effects of Light 

To increase forests’ ability to adapt to climate change, forestry practice is increasingly relying on greater tree-species diversity. Open canopy gaps caused by storms or droughts generally provide ideal conditions for many species. “However, we found that the impact of roe deer is particularly pronounced in these lighter areas,” explains Ludwig Lettenmaier, a doctoral researcher at the University of Würzburg. 

University Forest as a Prototype 

The study was conducted over four years in the Würzburg University Forest. The researchers established paired plots – one fenced and one unfenced, each measuring 36 square metres – both in artificially created canopy gaps and in shaded, closed forest areas. 

The results were clear: “The additional light could not offset the negative influence of the deer on the unfenced plots. Tree-species diversity was similar to that in the shaded areas,” says Lettenmaier. 

Potentially high tree-species diversity developed at heights up to 1.3 metres, which is the level at which deer feed and browse. However, due to the animals’ selective browsing, only a few species managed to grow beyond this susceptible zone. Regardless of light availability, this led to a halving of tree-species diversity. 

The study shows that roe deer, through their feeding preferences, drive a marked homogenisation of forest regeneration. Since deer densities in the University Forest are typical of many Bavarian deciduous forests, the researchers expect similar effects to occur on a wider scale. 

Implications for Forest Management 

After disturbances, the early developmental phase determines the future composition of forest stands. “If, in the first years, mainly less palatable species prevail, this will shape tree-species composition in the long term,” explains Jörg Müller, Professor of Conservation Biology and Forest Ecology. “Where deer densities cannot be adequately controlled, affected areas should be fenced for several years to allow the forest’s natural potential for greater diversity to unfold.” 

The findings provide valuable insights for integrated wildlife and forest management. They also demonstrate that light and browsing must not be considered separately when assessing the resilience of our future forests. 

Next Research Steps 

The next phase of the project will explore how deer browsing and light conditions affect the understorey vegetation and key ecosystem functions – such as wood decomposition, soil microbial respiration, earthworm populations, and arthropod diversity. 

Cooperation and Funding 

The study involved researchers from the University of Würzburg, the German Centre for Integrative Biodiversity Research (iDiv) Halle–Jena–Leipzig, and the Universities of Göttingen, Oslo and Zurich. 

The work was funded by the European Regional Development Fund (ERDF, project MainPro) and the German Research Foundation (DFG Research Unit BETA-FOR). 

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Journal

Journal of Applied Ecology

DOI

10.1111/1365-2664.70211 

Method of Research

Observational study

Article Title

Light and ungulate browsing interact in shaping future woody plant diversity through natural regeneration

Article Publication Date

5-Nov-2025

 

Can birds imitate Artoo-Detoo? Yes - and some are surprisingly good at it

Universiteit van Amsterdam

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The bird research summarized in an infographic

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Credit: Nick Dam (Leiden University), Henkjan Honing (university of Amsterdam) & Michelle Spierings (Leiden University)

When you think of birds imitating sounds, parrots and starlings might come to mind. They’re famous for copying human speech, car alarms, and even ringtone melodies. But what happens when you challenge them with something really complex, like the electronic beeps and boops of R2-D2, the beloved Star Wars droid? Researchers from the University of Amsterdam and the Leiden University put nine species of parrots and European starlings to the test.

Starlings versus parrots
It turns out that starlings had the upper hand when it came to mimicking the more complex 'multiphonic sounds. Thanks to the unique morphology of their vocal organ, the syrinx, which has two sound sources. This allows starlings to reproduce multiple tones at once—perfect for R2-D2-style chatter.

Parrots, on the other hand, are limited to producing one tone at a time (just like humans). Still, they held their own when it came to the simpler “monophonic” beeps of R2-D2. Interestingly, it weren’t the famously chatty African grey parrots or amazon parrots that did best, but the smaller species, like budgerigars and cockatiels. These little birds, often thought of as less impressive vocalists, actually outperformed the larger species in this specific task, likely by using different strategies to imitate sounds.

Even sounds from science fiction can teach us something real
The researchers call their study a fun but powerful window into how anatomy, like the structure of a bird’s vocal organ, can shape the limits and possibilities of their vocal skills. It is the first time that so many different species all produced the same complex sounds, which finally allows for a direct comparison. This shows that even sounds from science fiction can teach us something real about the evolution of communication and learning in animals.

And here’s the cool part: much of the sound data came from pet owners and bird lovers participating in citizen science through the Bird Singalong Project. With their help, the researchers were able to gather a richer, more diverse collection of bird sounds than ever before, proving that science doesn't always have to happen in a lab.

Details article
Nick Dam (Leiden University), Henkjan Honing (university of Amsterdam) & Michelle Spierings (Leiden University), What imitating an iconic robot reveals about allospecific vocal imitation in parrots and starlings, In: Scientific reports

The difference between the vocal organs of parrots and starlings

Credit

Nick Dam (Leiden University), Henkjan Honing (university of Amsterdam) & Michelle Spierings (Leiden University)

Journal

Scientific Reports

DOI

10.1038/s41598-025-23444-7 

Method of Research

Experimental study

Subject of Research

Animals

Article Title

What imitating an iconic robot reveals on allospecific vocal imitation in parrots and starlings

Article Publication Date

6-Nov-2025

 

CABI scientists suggest an accidentally introduced parasitoid could save box trees from ecological extinction

CABI scientists, who have published their research in the journal CABI Agriculture and Bioscience, suggest that an accidentally introduced parasitoid could help save wild box trees from ecological extinction.

 

CABI

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Box tree moth on leaf

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Credit: Tim Haye/CABI

 

CABI scientists, who have published their research in the journal CABI Agriculture and Bioscience, suggest that an accidentally introduced parasitoid could help save wild box trees from ecological extinction.

The study highlights how an unidentified species of Eriborus (Hymenoptera: Ichneumonidae) could be used as a classical biological control for box tree moth Cydalima perspectalis (Lepidoptera: Crambidae) in Europe and North America.

Scientists, which included those from the Natural History Museum Basel, Switzerland, and Seoul National University in South Korea, say that high parasitism rates observed at several sites in Switzerland and Germany provide hope for protecting and saving wild box trees from the box tree moth pest.

Seriously threatening the survival of European wild Buxus spp.

Dr Marc Kenis, Head Risk Analysis and Invasion Ecology at CABI and an author of the paper, said, “This parasitoid likely arrived unintentionally some years ago with the importation of box trees from East Asia. Cydalima perspectalis is seriously threatening the survival of European wild Buxus spp., and very few control options are presently available.

“The presence of this Eriborus sp. opens new perspectives for classical biological control in all invaded areas, including North America, where the box tree moth has become a serious pest of ornamental Buxus spp. and could threaten native Buxus spp. in Mexico and the Caribbean.”

In spring 2024, an Eriborus sp. adult was caught in a botanical garden in Basel, Switzerland. To the scientists’ knowledge, this was the first detection of this parasitoid in Europe. In spring 2025, surveys were made to assess parasitism of C. perspectalis populations at various sites in North-Western Switzerland and at one site in South-Western Germany.

These surveys showed that the parasitoid is well established in the region, both in gardens and in wild box tree stands. Morphological observations and molecular analyses showed that the specimens found in Switzerland and Germany belong to the same species as specimens collected on C. perspectalis in South Korea. Parasitism was highest in wild stands, reaching 68% in Germany and 32% in Switzerland.

Eriborus sp. is only one of many cases of adventive biological control

The scientists argue that Eriborus sp. is only one of many cases of adventive biological control of invasive species through the non-intentional introduction of natural enemies from the area of origin of the pests.

In recent years, several similar cases have been observed in Europe and elsewhere. These include, among others, the introduction of Trissolcus japonicus, parasitoid of Halyomorpha halys, Leptopilina japonica, parasitoid of Drosophila suzukii, several parasitoids of invasive Eucalyptus pests, and even herbivores of invasive weeds such as the beetle Ophraella communa, an accidentally introduced biological control agent of Ambrosia artemisiifolia.

These natural enemies take advantage of the high abundance of their host in the invaded areas to establish themselves and spread. In the case of Eriborus sp., the parasitoid being the lytokous, a single cocoon or a parasitized larva imported on box trees may be sufficient for successful establishment.

Dr Lukas Seehausen, Research Scientist, Risk Analysis & Invasion Ecology at CABI and a co-author of the paper, said, “Eriborus sp. could be distributed elsewhere in Europe, Western Asia and North America but, before that, it remains to be seen whether the species is sufficiently specific to avoid non-target effects on native moths.

“The first non-target experiments conducted in quarantine are promising but the presence of Eriborus sp. in Swiss and German forests will allow us to assess its realized host range in nature, by collecting a large variety of caterpillar species present at the right places in the right moments to determine whether they are parasitized by Eriborus sp.”

Additional information

Main image: The box tree moth is a native moth throughout eastern Asia and feeds on boxwood (Credit: ©Friedrich Boehringer/via wikipedia - CC BY-SA 2.5).

Full paper reference

Marc Kenis, Seraina Klopfstein, Minho Lee, Seunghwan Lee, M. Lukas Seehausen, ‘Will an accidentally introduced parasitoid save European box trees?,’ 6 November 2025, CABI Agriculture and Bioscience, DOI: 10.1079/ab.2025.0081

The paper can be read open access here: https://www.cabidigitallibrary.org/doi/10.1079/ab.2025.0081

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Journal

CABI Agriculture and Bioscience

DOI

10.1079/ab.2025.0081 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Will an accidentally introduced parasitoid save European box trees?

Article Publication Date

6-Nov-2025

Competing rivals can become powerful partners in global markets

A new study examines how European and Chinese firms use coopetition – a combination of competition and cooperation – and why managing trust and protection is vital for both sides.

University of Vaasa

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Shuwei Jiang, University of Vaasa.

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Credit: Photo: University of Vaasa.

In an era of geopolitical tensions and fragile supply chains, firms are seeking new ways to remain competitive and resilient. One such approach is coopetition, a strategic relationship in which companies cooperate and compete at the same time to achieve mutual benefit.

The coopetition arrangement is not uncommon in the automotive sector, where rival brands share production lines or jointly develop vehicle models to reduce costs and speed up innovation. Shuwei Jiang’s doctoral dissertation in strategic business development reveals that the same logic applies to European SMEs as well – particularly those aiming to enter the Chinese market.

– Partnering with competitors locally in the target market provides access to existing networks, distribution channels and financing mechanisms. In turn, Chinese firms benefit from advanced technology and global experience, Jiang explains.

A delicate balance of trust and self-protection

Despite its advantages, coopetition also carries some significant risks. The primary tension is self-protection, as companies are hesitant to share their latest technology or trade secrets with a firm that is also a rival. Jiang’s dissertation identifies mechanisms that help firms mitigate these risks, such as cross-shareholding structures that prevent power imbalances.

– When both sides hold a small share in each other’s company, any action that harms the partnership also affects their own interests. This structure encourages long-term commitment and reduces the temptation to act opportunistically, says Jiang.

While coopetition can be complex and occasionally fraught with tension, Jiang’s research concludes that its benefits outweigh the risks when managed carefully. Firms that succeed in balancing collaboration and competition gain access to new resources, innovation opportunities, and market resilience that would be difficult to achieve alone.

– The key lies in recognising coopetition as a long-term strategic choice rather than a temporary alliance of convenience. Coopetition is about sharing enough to create value together while protecting what defines your competitive edge. When this balance is achieved, both partners grow stronger in an increasingly uncertain world, Jiang concludes.

Doctoral dissertation

Jiang, Shuwei (2025) International Coopetitive Business Relationships Between European and Chinese Firms: Opportunities and Challenges. Acta Wasaensia 566. Doctoral dissertation. University of Vaasa.

Publication pdf

Further information

Shuwei Jiang was born in China. He moved to Finland in 2002 to study at Savonia University of Applied Sciences and began his professional career in an international business role, working for over ten years in Finland, China and Singapore. Jiang completed a Master’s degree in Strategic Business Development at the University of Vaasa in 2019 and has since continued his doctoral research in the same field.