Author: Isabel Barrio

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Large herbivore and carnivore populations in boreal and tundra ecosystems are highly variable in time and space

NordBorN researchers have estimated and mapped historic biomass densities of large herbivores and carnivores across Norway. The current high densities of wild ungulates, especially moose and roe deer, contrast with historically high densities of livestock. Carnivores show a low level of recovery from near absence in the mid 20th century. However, densities are far below where they were in the 19th century.

These findings have implications for borealization: Previous studies have shown that herbivory can prevent the spread of boreal species into the tundra, yet it is clear that the trophic interactions involving large herbivores and carnivores are highly dynamic in both time and space.

Reference: Speed, J.D.M, Sobocinski, A., Kolstad, A. L., Linnell, J. D., Solberg, E. J., Mattisson, J., & Austrheim, G. (2025). The trophic distribution of biomass in ecosystems with co-occurring wildlife and livestock. Scientific Reports, 15(1), 1474. https://www.nature.com/articles/s41598-025-85469-2

Photo: Lynx (Erik F. Brandsborg, CC BY-SA)

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Biotic components influence feedback loops between the tundra and the atmosphere

This paper published by NordBorN researchers in Frontiers in Environmental Science as part of the research topic Climate Change Impacts on Arctic Ecosystems and Associated Climate Feedbacks highlights the role of biota in feedback loops from tundra ecosystems to the atmosphere.

Ecosystem modelling has greatly improved or understanding of ongoing and future changes in the Arctic, but beyond vegetation and to some extent microbes, most ecosystem models still do not consider the influence of biotic components on feedback loops between biosphere and atmosphere. This article provides an overview of the influence of three key ecosystem compartments (vegetation, decomposers and herbivores) on three key feedback loops between tundra and atmosphere
(carbon dynamics, albedo and permafrost thaw). Including these dynamics
into ecosystem models will likely improve the magnitude, accuracy and credibility of model projections.

Reference: Schmidt, N.M., Barrio, I.C., Kristensen, J.A., López-Blanco, E. and Van Beest, F.M., 2024. Highlighting the role of biota in feedback loops from tundra ecosystems to the atmosphere. Frontiers in Environmental Science, 12, p.1491604. https://doi.org/10.3389/fenvs.2024.1491604

Photo: diagram of feedback loops mediated by biota from tundra ecosystems to the atmosphere (credit: Niels Martin Schmidt)

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Mathilde Defourneaux defends her PhD

Mathilde Defourneaux is defending her PhD on Wednesday December 18, 2024 at 14:00 GMT.

Mathilde’s thesis, entitled The impacts of spatio-temporal shifts in vertebrate herbivore communities on the functioning of the Icelandic tundra will be defended at the Faculty of Environmental Sciences of the Agricultural University of Iceland. Mathilde’s supervisors are Prof. Isabel C Barrio (Agricultural University of Iceland), Prof. James D.M. Speed (Norwegian University of Science and Technology) and Ass.Prof. Noémie Boulanger-Lapointe (University of Victoria). The opponents in the defence will be Prof. Robin Pakeman (The James Hutton Institute) and Dr. Camilla Fløjgaard (Aarhus University).

The defence will take place at the AUI campus in Keldnaholt, but you can also follow online. A link will be provided on the university website closer to the date.

It is not only a big day for Mathilde, but also for NordBorN, as Mathilde is also formally the first NordBorN PhD student to graduate!

All the best from the NordBorN team for your big day Mathilde!