Author: isabel

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Call for collaboration: Emerging priorities in terrestrial herbivory research in the Arctic

After 10 years of contributing to circumpolar research on plant-herbivore interactions, the Herbivory Network is proposing to use a horizon scan to identify research priorities in Arctic herbivory for the coming decade, as a contribution to the ICARP IV (Fourth International Conference on Arctic Research Planning – 2025) process.

For this exciting aim, we are asking for input that will help identify the most important questions to solve the puzzle of herbivory dynamics in the Arctic, by completing this short online survey.

The survey asks you to name one or more priorities for Arctic research in the next decade. These priorities can range from local- to large-scale issues, well-known topics or under-appreciated ones, urgent concerns as well as more distant ones.

Deadline for submissions has been extended until January 28, 2024.

The survey responses will be compiled and organised into thematic categories by a core working group. Subsequently, an in-person workshop is scheduled for March 12, 2024 in Lund, as part of the NSO 2024 conference, to further refine the emerging themes and determine key action points. We anticipate that this collaborative process will be beneficial to ICARP’s objectives while fostering the generation of new knowledge in the field of Arctic herbivory.

This project has been endorsed by the International Arctic Science Committee as an ICARP IV activity.

Photograph: Cambridge Bay (Cléa Frapin)


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Call for collaboration: collecting fresh herbivore faecal samples

Herbivores are important drivers of nutrient dynamics in terrestrial ecosystems. By consuming plants and releasing nutrient-rich resources to the soil, herbivores affect nutrient cycling. Near Infrared Spectroscopy (NIRS) represents an effective, low-cost method to assess the nutrient contents of herbivore dung, alternative to more expensive traditional chemical laboratory analyses, but it requires calibration with samples of known chemical content.

Here is where we need your help! We need to collect fresh faecal samples from accurately identified herbivore species. If you are going to the field this summer and you have the chance to collect very fresh faecal matter that you can unequivocally ascribe to a species of herbivore (for example, if you are working with live trapping, culled animals, enclosure experiments, or visiting colonies and nests), we would be very happy to receive samples from you!

The sample collection protocol is very simple (more detailed guidelines are available here). Samples will be shipped to the Agricultural University of Iceland, where all analysis will be conducted. In addition to NIRS calibration curves, the data obtained from these samples will contribute to an open database on nutrient content of herbivore dung. Data contributors will be invited as co-authors of relevant outcomes of this project.

Developing NIRS calibration curves for faecal nutrient content of Arctic herbivores will allow analysing a much larger number of samples needed to address questions at finer temporal and spatial scales, for example, to assess seasonal variation of faecal nutrient contents over the growing season, or to assess herbivore diet quality at different sites. This project will provide a significant methodological advance in the field and will increase our understanding of how herbivores contribute to nutrient cycling in tundra ecosystems.

If you are interested in contributing to this project, please get in touch with Mathilde Defourneaux (mathilde@lbhi.is).

Relevant documents

This project is a contribution to the TUNDRAsalad project funded by the Icelandic Research Fund (grant nr. 217754 )

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HN meeting in Cambridge Bay 2023

The Herbivory Network 2023 meeting took place in Cambridge Bay, June 13-16, 2023. The meeting was hosted at the Canadian High Arctic Research Station (CHARS), a leading research facility run by Polar Knowledge Canada (POLAR) in the community of Cambridge Bay, Nunavut.

The next HN meeting will be hosted at the Canadian High Arctic Research Station (CHARS) in Cambridge Bay

The aim of the meeting was to advance and discuss ongoing projects and start new collaborations that will contribute to a better understanding of the effects of herbivores on arctic ecosystems. The meeting included an open public lecture and a short field visit. Eleven researchers from five Arctic countries participated in person in the meeting, and online access was provided to other participants to some of the discussion sessions. Meeting participants also visited the research station and shared about various (contrasting) field contexts stimulated by the direct field experience of the High Arctic tundra.

Participants to the Herbivory Network meeting at the Canadian High Arctic research station in Cambridge Bay.

Activities during the meeting

During this Herbivory Network meeting a strong emphasis was placed on presentations by participants on their current research projects. As well, a field session included the demonstration of an observational protocol for data collection. We also had a brainstorming session on the potential contribution of Herbivory Network researchers to the ICARP IV process and an open public lecture attended by community members in Cambridge Bay.

  • Presentations by participants: during the meeting participants were encouraged to give a short presentation about their ongoing research, ideas for future collaboration or anything they wished to share with the network. Presentations from in-person and online participants covered topics including updates from the HN Soil Working Group, research on aapa mires, a systematic review on the effects of herbivore diversity on tundra ecosystems, trophic food webs across the Arctic, or the effects of fertilization and goose grazing exclosure on permafrost, among others.
  • Coordinated protocols to assess the effects of herbivore diversity on tundra: within the IRF-funded project TUNDRAsalad that aims at investigating the effects of herbivore diversity on tundra ecosystems, we have designed an experimental and an observational protocol for data collection across tundra sites (https://herbivory.lbhi.is/tundra-exclosure-network-texnet/). WP leader Elina Kaarlejärvi successfully secured funding from INTERACT Transnational and Remote Access to implement the observational protocol in Cambridge Bay and other INTERACT stations across the Arctic. Data collection during the meeting was not possible because it was too early in the season, but we demonstrated the use of the protocol so that meeting participants can then implement the protocol at their study sites in summer 2023 or 2024. The demonstration included a visit to the field with discussions on the ground.
  • Brainstorming session on contribution of HN to the ICARP IV process: the Fourth International Conference on Arctic Research Planning (ICARP IV; https://icarp.iasc.info/) lasting from 2022 until 2026 is a planning process that will engage Arctic researchers, Indigenous Peoples, policy makers, residents and stakeholders from around the world to collegially discuss the state of Arctic science, and the place the Arctic occupies in global affairs and systems. During the HN meeting participants unanimously acknowledged the significance and timeliness of the ICARP IV process and expressed their eagerness to contribute using a horizon scanning approach to identify research priorities in Arctic herbivory for the next decade. An online survey was developed and will be distributed to Herbivory Network members and to other interested researchers. The survey responses will be compiled and organised into thematic categories by a core working group. Subsequently, an in-person workshop is scheduled for 2024 to further refine the emerging themes and determine key action points. We anticipate that this collaborative process will be beneficial to ICARP’s objectives while fostering the generation of new knowledge in the field of Arctic herbivory.
  • Public lecture: Prof. Esther Lévesque from the Université du Québec à Trois-Rivières, gave a talk titled “Greener Arctic: more shrubs, less berries?” where she presented her work with local communities in the Canadian Arctic. Community members in Cambridge Bay attended the meeting and discussed their knowledge on berries in the region.

Meeting agenda

[all times are local times, Mountain Standard Time, GMT-7]

Monday June 12, 2023 – arrival of participants to Cambridge Bay

Tuesday June 13, 2023
8:30-10:00 Presentations by participants on ongoing research projects and initiatives (online access to other participants)
10:30-12:00 Presentations by participants (cont.)
13:00-15:00 Coordinated protocols to assess the effects of herbivore diversity on tundra
15:30-17:00 POLAR Knowledge Canada and tour of CHARS
19:00-20:00 Open public lecture: Greener Arctic: more shrubs, less berries? By Prof. Esther Lévesque, Université du Québec à Trois-Rivières

Wednesday June 14, 2023
8:30-16:00 Coordinated protocols (cont.): implementation in the field
16:00-17:00 Presentations by participants (cont.)

Thursday June 15, 2023
8:30-15:30 Presentations by participants (cont.)
16:00-18:00 Brainstorming session on contribution of HN to the ICARP IV process

Friday June 16, 2023
8:30-10:00 Future collaboration within the network (online access to other participants)
10:30-12:00 Closing remarks and conclusions

Archived documents

Funding and support

Support for organizing the meeting was kindly provided by the Terrestrial Working Group of the International Arctic Science Committee (IASC). INTERACT Transnational Access facilitated participation of researchers to demonstrate and promote the use of a coordinated protocol for data collection. Polar Knowledge Canada provided in-kind support for the organization of the meeting.

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PhD in biodiversity and ecosystem functioning in boreal forest and tundra

Deadline: Jan 8 2023

A fully-funded 4-year PhD researcher position in biodiversity and ecosystem functioning in boreal forest and tundra is available within the recently established research group Northern Biodiversity and Ecosystem Functioning (NorEcoFun) at the University of Helsinki.

You can find more information on the project and how to apply here. Deadline for applications is January 8, 2023 and expected starting date is ideally in March 2023, but can be negotiated.

For more details, get in touch with Elina Kaarlejärvi.

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Model responses to CO2 and warming are underestimated without explicit representation of Arctic small-mammal grazing

We use a simple model of coupled carbon and nitrogen cycles in terrestrial ecosystems to examine how explicitly representing grazers versus having grazer effects implicitly aggregated in with other biogeochemical processes in the model alters predicted responses to elevated carbon dioxide and warming. The aggregated approach can affect model predictions because grazer-mediated processes can respond differently to changes in climate from the processes with which they are typically aggregated. We use small-mammal grazers in arctic tundra as an example. We conclude that implicitly aggregating the effects of small-mammal grazers with other processes results in an underestimation of ecosystem response to climate change relative to estimations in which the grazer effects are explicitly represented. The magnitude of this underestimation increases with grazer density. We therefore recommend that grazing effects be incorporated explicitly when applying models of ecosystem response to global change.

Reference: Rastetter, E.B., Griffin, K.L., Rowe, R.J., Gough, L., McLaren, J.R. and Boelman, N.T., 2022. Model responses to CO2 and warming are underestimated without explicit representation of Arctic small‐mammal grazing. Ecological Applications, 32(1), p.e02478. Link to publisher

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Herbivore absence can shift dry heath tundra from carbon source to sink during peak growing season

In arctic tundra, large and small mammalian herbivores have substantial impacts on the vegetation community and consequently can affect the magnitude of carbon cycling. However, herbivores are often absent from modern carbon cycle models, partly because relatively few field studies focus on herbivore impacts on carbon cycling. Our objectives were to quantify the impact of 21 years of large herbivore and large and small herbivore exclusion on carbon cycling during peak growing season in a dry heath tundra community.

When herbivores were excluded, we observed a significantly greater leaf area index as well as greater vascular plant abundance. While we did not observe significant differences in deciduous dwarf shrub abundance across treatments, evergreen dwarf shrub abundance was greater where large and small herbivores were excluded. Both foliose and fruticose lichen abundance were higher in the large herbivore, but not the small and large herbivore exclosures. Net ecosystem exchange (NEE) likewise indicated the highest carbon uptake in the exclosure treatments and lowest uptake in the control (CT), suggesting that herbivory decreased the capacity of dry heath tundra to take up carbon. Moreover, our calculated NEE for average light and temperature conditions for July 2017, when our measurements were taken, indicated that the tundra was a carbon source in CT, but was a carbon sink in both exclosure treatments, indicating removal of grazing pressure can change the carbon balance of dry heath tundra. Collectively, these findings suggest that herbivore absence can lead to changes in plant community structure of dry heath tundra that in turn can increase its capacity to take up carbon.

Reference: Min, E., Wilcots, M.E., Naeem, S., Gough, L., McLaren, J.R., Rowe, R.J., Rastetter, E.B., Boelman, N.T. and Griffin, K.L., 2021. Herbivore absence can shift dry heath tundra from carbon source to sink during peak growing season. Environmental Research Letters, 16(2), p.024027. Link to publisher

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Graduate PhD Assistantship Available: Climate Change Responses in Coastal Arctic Wetlands

Deadline: December 15, 2022.

A PhD student position with 4 years of funding is available to participate in an NSF-funded project examining the interaction of multiple climate change forcings on vegetation and ecosystem functioning in Arctic wetlands through field and laboratory research. Field work is conducted in the Yukon-Kuskokwim Delta in Alaska and will involve an experiment with flooding, warming, and herbivory treatments followed by measurements of vegetation responses, and CO2 and CH4 gas fluxes. The successful candidate must start no later than 1 May 2023 (although 1 April 2023 is preferred), and be willing to work 3 months each summer (number of field seasons is contingent on project development) in an extremely remote setting in western Alaska (e.g., no internet service, no running water). This work is a collaboration between faculty at South Dakota State University, the University of Colorado-Denver and Utah State University, and the student would interact with personnel from each location. The successful candidate will receive a tuition waiver; a 12-month stipend ($24,000/yr); and room, board and travel expenses during the summer field seasons.

Required Qualifications: (1) A BS/BA degree in Biology, Ecology, Environmental Science, Natural Resource Management, or related field by December 2022; (2) strong academic record including previous research experience; (3) quantitative skills including introductory R; (4) excellent written and oral communication skills.

Preferred Qualifications: (1) Prior experience conducting field research in or living in remote settings for extended periods; (2) experience with ATVs and small craft boats: (3) experience in plant identification; (4) experience with LICOR or other gas exchange systems; (5) MS degree preferred.

Utah State University is a highly selective, public, land-grant university and is classified as a Carnegie R1 Research University. The main campus is located in Logan, a community of 100,000 people. The Beard Lab is committed to supporting and advancing diversity in STEM. Applications from members of historically underrepresented groups are strongly encouraged.

To apply, please send a single PDF with (1) CV; (2) a letter describing how you meet the required qualifications and any preferred qualifications, research interest, and career goals; (3) unofficial transcripts; and (4) contact information for three professional references to Karen Beard (karen.beard@usu.edu). Application deadline is December 15, 2022.

Research station in Yukon-Kuskokwim Delta, Alaska
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PhD position in bryophyte ecology with the Faculty of Life and Environmental Sciences

Deadline for applications is November 18, 2022.

The Faculty of Life- and Environmental Sciences at the University of Iceland is seeking a motivated candidate for the project: Bryophytes as ecosystem engineers in a changing tundra. The position is funded by the University of Iceland Research Fund for three years. The PhD project will be linked to larger funded projects.

Bryophytes are a major component in many tundra plant communities and potentially have multiple effects on the physical environment of tundra ecosystems as well as providing a habitat for diverse organisms building complex food webs. The aim of the PhD project is to investigate bryophyte functional traits, including the microbial/micro faunal traits, that drive ecosystem processes in tundra rangelands of Iceland (above potential tree line), and how they vary between Bryophyte Functional Groups, climatic condition, and herbivory. Within that framework the successful candidate will be given the opportunity to formulate relevant research questions.

The position is funded by the University of Iceland Research Fund for three years. The PhD project will be linked to larger funded projects.

More information can be found here: https://euraxess.ec.europa.eu/jobs/845469

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Small but mighty: structures created by small mammals affect C and nutrient cycling in arctic tundra

While typically thought of as having top-down roles in ecosystems, small mammal herbivores bottom-up roles are often underappreciated. As structure builders, small mammals can impact ecosystem function through alterations of soil nutrient cycling. We examined the effects of small mammal-built structure types (hay piles, runways, latrines) on soil and plant biogeochemical cycling across three tundra ecosystems in northern Alaska.

We found that structures play important roles in regulating soil nitrogen levels, regardless of tundra ecosystem. However, different structures influence soil nutrients in different ways. Hay piles increased soil N and plant P, while latrines influenced soil C, N, and P, and runways mainly affected soil N. We also found strong changes in the cover of structures on tundra during different phases of the small mammal population cycle.

Structures built by small mammals have the ability to increase or decrease biogeochemical cycling rates and arctic ecosystem function. Additionally, changes in the abundance of these structures may create pulses of resource availability during the high phase of the population cycle or may aid in maintaining ecosystem function when animals are rare on the landscape. Our work highlights the roles that small mammals play in the bottom-up regulation of tundra ecosystems and the need to include small mammals in our understanding of ecosystem function.   

You can read the full paper here: https://doi.org/10.1111/1365-2435.14127

Reference: Roy, A., Gough, L., Boelman, N.T., Rowe, R.J., Griffin, K.L. and McLaren, J.R., 2022. Small but mighty: Impacts of rodent‐herbivore structures on carbon and nutrient cycling in arctic tundra. Functional Ecology.

Text: Austin Roy, University of Texas at El Paso. This paper is a contribution of Team Vole, a group of collaborative scientists seeking to understand the impacts of small herbivores on carbon and nutrient cycling in tundra ecosystems.

Photo credit: Luke Johnson

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