Category: news

We are very happy to welcome Laura Barbero Palacios to the TUNDRAsalad team! Laura arrived in Iceland in July, and for the next 12 months she will be working on a systematic review on the effects of herbivore diversity on tundra ecosystems. This project is a joint contribution to TUNDRAsalad and the EU-funded CHARTER project.

Laura completed her degree in Biology at the University of Girona and completed a MSc degree in Terrestrial Ecology and Biodiversity Management at the Autonomous University of Barcelona, under the supervision of HN member Emmanuel Serrano. Laura is interested in the role of herbivores as ecosystem engineers, particularly on their effects on biogeochemical cycles. For her MSc thesis Laura conducted a systematic review aimed at synthesizing the effects of large herbivores on biogeochemical models across terrestrial biomes.

Welcome to the TUNDRAsalad team!

The TUNDRAsalad team is growing! Mathilde Defourneaux joined the Agricultural University of Iceland in May 2021 to develop her PhD on the effects of spatio-temporal changes of herbivore assemblages on Icelandic tundra ecosystems. Mathilde will investigate how herbivore communities have changed in Iceland over time and what impacts these changes have had on Icelandic ecosystems. She will estimate current impacts of different herbivore assemblages across Iceland and at a finer spatio-temporal resolution, she will assess how herbivore impacts vary at a landscape scale within the growing season. Mathilde’s PhD supervisors are Isabel C Barrio at the Agricultural University of Iceland, Noémie Boulanger-Lapointe at the University of Iceland and James Speed at the Norwegian University of Science and Technology.

Mathilde has an MSc degree in landscape management from Agrocampus Ouest. Before moving to Iceland, Mathilde spent eighteen months in Crozet, Subantarctic Islands, studying the effects of climate change, human activities and introduced species on terrestrial ecosystems, with the programme SubantEco of the French Polar Institute (IPEV). After returning to France, she worked as a technician in data analysis and modelling at the CNRS in Rennes. Among Mathilde’s hobbies are scientific illustration and photography.

Welcome to the TUNDRAsalad team!

Save the date! Next April 16, 2021, Katariina Vuorinen will defend her thesis titled “When do ungulates override the climate? Defining the interplay of two key drivers of northern vegetation dynamics“. Kata’s thesis has been carried out at the Faculty of Natural Sciences, Norwegian University of Science and Technology (NTNU), under the supervision of James Speed, Gunnar Austrheim, Allison Hester and Jean-Pierre Tremblay. 

As a requirement of Norwegian universities, Katariina will have first a trial lecture on a topic related to her thesis work, followed by the public defence of her thesis.

• The trial lecture will be at 10:15 Norwegian time. The topic of her trial lecture will be: Looking back in time and space: how and where did Pleistocene megaherbivores affect vegetation? The Zoom link for the presentation will be announced here closer to the date.
• The public defence will be at 13:15 Norwegian time. The Zoom link for the presentation will be announced here closer to the date.

Summary of the thesis

Climate change is expected to transform the vegetation of the Earth, and thus cascade through ecosystems from bottom-up. However, ecological processes rarely work like a one-way street. Top-down effects of herbivores can change vegetation, and thus modify and even counteract the effects of warming. In northern ecosystems, ungulate herbivores such as deer, moose, reindeer, muskox, and sheep may decrease tree growth, prevent shrub expansion and shape vegetation communities.
From the viewpoint of forestry and forest restoration, increasing mean temperatures may bring desired boost for tree growth, whereas ungulates cause undesired growth decrease by browsing the trees. In contrast, in arctic and alpine environments, warming may drive shrub advancement and closing-up of the vegetation with detrimental effects to tundra species and ecosystem functioning, and thus the counteracting force of ungulates can be seen as a positive management tool that may be used to mitigate the impacts of warming. To adapt ungulate management to the prevailing and future climatic conditions for preserving and achieving desired vegetation states, knowledge on the combined effects of climate and ungulates is urgently needed.
In this thesis, I studied the interplay of climate and ungulates in affecting the vegetation of tundra and boreal forests within multiple different ecological contexts. I identified conditions under which ungulates are likely to counteract climatic effects on tree growth, shrub growth and functional structure of plant communities. With this approach, I aimed at answering the question: When do ungulates override the climate?
The results showed that climate and ungulate effects on plants may depend on each other, and that their effects vary between different ecological contexts across northern biomes. Deer were shown to counteract the effect of temperature on pine growth in the Scottish Highlands, and the effect of browsing intensity increased at high temperatures. Similarly, moose counteracted the effects of warming on boreal tree growth in Norway and Canada, but only for preferred forage species. Reindeer, muskox and sheep had a weak negative effect on tundra shrub growth, and this effect was only detected at intermediate temperatures but not at the coldest and the warmest parts of the Arctic. The functional composition of alpine plant communities in Norway showed high resistance to changing sheep densities, but there was evidence for a moderate climate-driven increase in plant size. These results may be useful for management purposes, and help us to achieve and retain desired vegetation states under changing climatic conditions.

You can access the full thesis here.

The thesis has already resulted in two publications:

• Vuorinen, K.E., Rao, S.J., Hester, A.J. and Speed, J.D., 2020. Herbivory and climate as drivers of woody plant growth: Do deer decrease the impacts of warming?. Ecological Applications, 30(6): e02119 link to publisher
• Vuorinen, K.E., Kolstad, A.L., De Vriendt, L., Austrheim, G., Tremblay, J.P., Solberg, E.J. and Speed, J.D., 2020. Cool as a moose: How can browsing counteract climate warming effects across boreal forest ecosystems?. Ecology, 101(11): e03159 link to publisher

A research project, starting out of the University of Gothenburg, Sweden, to provide data across arctic vertebrate exclosure sites, is currently seeking collaborators!

Cole Brachmann and Robert Björk are beginning an experiment to evaluate the growth of fungal mycelia in arctic soils and how it is affected by the presence of herbivory and increasing abundance of deciduous and evergreen shrubs. The change in abundance and diversity of fungal mycelia under different herbivory regimes and dominant shrub communities has implications on soil carbon storage in the Arctic. Their study aims to determine potential feedback effects on climate change through herbivory-mediated shrub expansion and their associated mycorrhizal fungi altering carbon storage in the soil.

They are calling for collaborators to assist with the collection of mycelia and soil samples through the use of mesh bags and composite soil sampling at vertebrate exclosure experimental sites. You can find more information about the project and proposed sampling plan here.

If you are interested and want to know more about the experiment or if you
have any questions, please contact Cole Brachmann by email at cole.brachmann@gu.se.

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Photo © Richard Humphrey (cc-by-sa/2.0)

Some of you may be familiar with the Herbivory Network project “systematic map of arctic herbivory”. After publishing a “protocol for systematic map” we are now inviting all HN members to co-author the systematic map publication. To join the co-author team you will need to do about a week of work – including i) few days on various small tasks such as scoring papers for inclusion/exclusion, doing searches on various databases, extracting data from papers, and ii) commenting on the manuscript. We will also have a session at the HN meeting in September to work on data analysis/manuscript.

If you are interested in contributing to this effort, please get in touch with Eeva Soininen (eeva.soininen@uit.no).

Short intro to the project

In general, the effects of herbivores on plants and ecosystem functioning depend on the ecological context where the interaction takes place. For example, plants can respond to herbivory differently depending on local soil conditions such as fertility or salinity. Yet, research on herbivory in tundra environments has, until recently, been surprisingly local in extent. The conclusions of local studies on herbivory are thus inevitably affected by the ecological context of the study. Hence, to what extent the current research covers possible ecological contexts is an essential determinant of the general conclusions that can be drawn about the role of herbivory for arctic ecosystems change. Furthermore, the robustness of such conclusions is also pending on the coverage of the underlying ecological contexts. The main idea is to map the ecological contexts in which herbivory has been studied in the Arctic. By understanding which ecological contexts have been more studied and which are underrepresented, we will be able to draw a more robust picture of the effect of herbivory in tundra ecosystems and its variability, given current and past research efforts and the available evidence.

The short online course Sheep in the Land of Fire and Ice is now open for registration! You can access the course through the course website or using the link below: 

Access the course

Over the last year, Isabel C Barrio and David Hik have been developing a short Massive Open Online Course (aka micro-MOOC) on sheep grazing in Iceland. The course, titled Sheep in the Land of Fire and Ice, consists of a series short videos reviewing the history, socioeconomic factors and environmental conditions that have influenced the management of grazing resources in Iceland.

We use Iceland as a case study, to illustrate how land uses can have dramatic influences on the landscape.

This is a short open online course (estimated completion time is around 2 hours) that has been developed in collaboration with the University of Iceland, the Agricultural University of Iceland, the Soil Conservation Service of Iceland and the United Nations University Land Restoration Training Programme. We hope you like it!

Sarah Rheubottom defended her MSc at the University of Alberta in January 2018, on measuring invertebrate herbivory in tundra. Her work was based on the sampling that was coordinated in summer 2015 and to which many HN members contributed. Sarah spent hours on end behind the magnifier glass, looking at leaves of 46 species of tundra plants from 22 sites across the tundra. Sarah’s work contributes a basic understanding of the occurrence and intensity of invertebrate herbivory at different tundra sites, and will help develop a more general protocol to measure invertebrate herbivory in tundra. If you are interested in getting a copy of Sarah’s thesis, please contact her!