Audrey Veillette: Recipient of a NSTP scholarship for the upcoming 2017 field season

May 16, 2017 in @en, Article, post by Davesne.G

Congratulations to Audrey Veillette who was awarded a Northern Scientific Training Program grant for supporting her work on Ward Hunt Island this summer. She will be there from May 31st to July 12, working on the field with her colleague Gautier Davesne.

Audrey Veillette in Bylot Island in mai 2016

Congrats to Karine Rioux for its excellent talk at Géoforum!

April 24, 2017 in @en, Article by Davesne.G

On the 21st of April, Karine Rioux presented the main part of her honors bachelor project. Her presentation was part of the GeoForum 2017 of the Geography department (University of Montreal). Her project consists in evaluating the efficiency of a mitigation technique; the use of snowsheds to increase the thermal stability of permafrost along an experimental section of the Alaska Highway (Yukon). Karine skillfully demonstrated thermal dynamics of the air and the firsts centimeters of permafrost under the snowsheds, compared with a test section. Her good work and communicating skills won her the prize of the best honors presentation in physical geography! Congratulations Karine!

Yukon – Ecological gradation (Michel Sliger)

November 8, 2016 in Article, focus-en, post by Sliger.M

The limit separating the site’s different ecosystems is generally gradual at the Beaver Creek study site (Yukon). From the ground, they are definitely unperceivable. The 6m high road embankment is a better point of view but the best one would be the neighbour hill. According to the local knowledge, the 8km walk across the muskeg to the plateau on the left of the picture take two days. The St-Elias range (the white mountains in the background) are 23km south-westward (Figure 1).

tundra-arbres

Figure 1: Succession of ecosystem, view from the road

“Cold War” in Potsdam, June 2016 (Vilmantas Prėskienis)

October 26, 2016 in Article, post by Davesne.G

Remember these days when USSR and USA were the two competing powers, and Europe with China were just little players? No? Me neither (I’m too young). But my trip to Potsdam last June reminded me of that. This was the 11th ICOP (International Conference on Permafrost), at which close to half of the participants were from Russia, other big delegation from Alaska (and some other states), and then smaller groups of researchers and students from other “satellite countries”, including Canada, China, Sweden, Germany, UK, etc. Here for a full week, the cold war (or war for cold) continued as in old times.

My name tag bore only the indication that I’m from Canada and my exotic name, which allowed me to be a perfect spy for… I don’t even know who yet. The Alaskans (and their colleagues from other states) were more suspicious about me mingling around, since everyone is expected to understand English, as it was the language of the conference; however I managed to secretly retrieve some information from Russians, French, Swedish and Germans, who had no suspicion I might grasp some words in their languages.

Overall this was a great conference, where every new day brought lots of excellent ideas, and taught me more than a semester-long course at a university. I met my old friends and made some new acquaintances, and finally I’ve learned again, that having lots of nice pictures on your poster is never a bad idea!

Vilmantas

Vilmantas in front of his poster at the ICOP in Potsdam

New paper in Biogeosciences: Thermo-erosion gullies boost the transition from wet to mesic tundra vegetation

March 14, 2016 in Article, post by Perreault.N

Field surveys were conducted over two years in the Qarlikturvik valley of Bylot Island, NU to assess the impacts of thermo-erosion gullies on the vegetation of surrounding low-centered wet polygons. Based on 197 sites located around three gullies, plant species richness, plant species abundance and graminoid above-ground biomass of breached polygons were compared to those of two baseline habitats – intact wet polygons and intact mesic environments.

lamarque-bylot-1

lamarque-bylot-2

The inception of ice wedge degradation immediately decreased soil moisture and thaw front depth of breached polygons – as found by Godin et al. (2016) – and the environmental conditions of disturbed polygons thus got closer to those of mesic environments. Consequently, we observed a gradual but marked shift in vascular plant community composition within ten years after disturbance, characterized by the emergence of Arctagrostis latifolia and Salix spp. at the expense of hydrophilic species such as Carex aquatilis, Eriophorum scheuchzeri and Dupontia fisheri.

High Arctic wetlands are therefore highly sensitive to thermo-erosion processes, which can rapidly drive the transformation of low-centered wet polygon landscape. The transition towards mesic environments could soon impact food resources of herbivores – which are fond of hydrophilic species – and modify emissions of greenhouse gases.

Interestingly, the latest observations showed that, ten years after disturbance inception, hydrology and thaw regimes of breached polygons have not reached equilibrium with new conditions yet whilst cover of mesic bryophytes and dominant shrubs are still lower than in adjacent intact mesic environments. This paves the way for long-term monitoring studies of permafrost disturbance and recovery of its associated vegetation.

 

lamarque-bylot-3

 

The full story is available here:

Perreault, N., Lévesque, E., Fortier, D. and Lamarque L. J.: Thermo-erosion gullies boost the transition from wet to mesic tundra vegetation, Biogeosciences, 13, 1237-1253, 2016.

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by Godin.E

New paper in Biogeosciences: Nonlinear thermal and moisture response of ice-wedge polygons to permafrost disturbance increases heterogeneity of high Arctic wetland

March 10, 2016 in Article, post by Godin.E

The floor of the Qalikturvik valley (Bylot Island, NU) is a mosaic ice-wedges polygons. A subtype of polygons named wet polygons are bowl like shaped, which enable moisture from snowmelt and precipitation to concentrate in their centers. These fields of wet polygons can support productive ecological environments, particularly when considering the usually arid nature of the High-Arctic.

Thermal erosion gullying erode and breach the contour (rims) of the bowl-shaped polygons, therefore affecting their capacity to retain moisture and possibly changing the near-surface thermal regime. One gully can breach the rims of hundreds of polygons: at the study site, three dozen gullies were located.

Nearby polygons located near a gully were identified and instrumented; reference and intact polygon characteristics were compared against eroded polygons during 2012-2013. The intact polygon center was saturated following snowmelt and during precipitation events later in summer. The moisture diminished following the thickening of the active-layer and its overall moisture was significantly higher than any disturbed polygons. The thermal regime during 2012-13 for this polygon was similar to another intact polygon. The vegetation in its center was well distributed and relatively uniform (ex: Carex sp.).

On the other hand, disturbed polygons were characterized by varying state for their moisture, ground temperature and vegetation cover. A disturbed polygon could simultaneously be partially dry, partially wet, depending on the severity of the rims breach. The active layer evolution could be similar to an intact polygon or could be significantly thinner. Dry tussocks were present in the centers, underlining the changing moisture state of the polygon, where plants better adapted to the new conditions settled. Therefore in the eroded polygon centers, there was an intra-polygonal variability as there was an heterogeneity in the moisture levels and plant distributions and an inter-polygonal variability (as in not all disturbed polygon were affected in the same way), depending on the severity of the breach, the recharge capability and proximity to the gully.

At the scale of the decade, gullying cause heterogeneity in the landscape with a tendency toward a dryer environment than pre-gullying. Further, gullying affect polygons rims thus the area affected by the erosion exceeds the gully as it affects an entire disturbed polygon.

The paper is available here:

Godin, E.; Fortier, D. & Lévesque, E.
Nonlinear thermal and moisture response of ice-wedge polygons to permafrost disturbance increases heterogeneity of high Arctic wetland
Biogeosciences, 2016, 13, 1439-1452

 

 

by Godin.E

GHG emissions from Canadian Arctic aquatic systems dated for the first time

December 22, 2015 in Article by Godin.E

Bylot Island ponds and lakes: Carbon sinks or GHG emitters?

*all credits: http://www.inrs.ca/english/actualites/ghg-emissions-canadian-arctic-aquatic-systems-dated-first-time by Gisèle Bolduc*

For the first time, researchers have successfully dated the carbon dioxide (CO2) and methane (CH4) emitted by ponds and lakes on Bylot Island, Nunavut. The research team observed significant variability in age and emission rates of greenhouse gases (GHG) from aquatic systems located in a continuous permafrost zone. The study, whose lead author is Frédéric Bouchard affiliated to the INRS Eau Terre Environnement Research Centre and the Geography Department of Université de Montréal, appeared in the international journal Biogeosciences.

 

Gas samples taken over the summer showed strikingly different ages and emission rates depending on the size and depth of the water bodies. Carbon-14 dating revealed that gas emitted by shallow ponds was a few centuries old, making it relatively “young”. Certain ponds, covered by cyanobacterial mats, were identified as CO2 sinks and sources of CH4; others, with eroded banks, were significant emitters of both GHG. Compared to ponds, arctic lakes were found to release much older GHG—up to 3,500 years old in the case of CH4—but at a much slower rate, at least in summer.

“This study demonstrates the significant impact of the combined geomorphological, limnological, and hydrological properties of aquatic systems on CO2 and CH4 emissions caused by thawing permafrost,” noted Professor Isabelle Laurion.”

The research team approach enabled an estimation of GHG emissions caused by two distinct processes: diffusion and ebullition. Researchers found that diffusion can be a significant mode of emission, especially from ponds. Until now, ebullition had been considered the predominant mode of CH4 emissions in lake systems.

 


“This study on the age of GHG emitted in the Canadian Arctic is one of very few using data from lakes outside of Siberia or Alaska. It sheds light on the specific role played by aquatic systems on carbon dynamics associated with thawing permafrost, and their potential impact on future climate change,” stated researcher Frédéric Bouchard

This work sets the scene for further research that must not only measure gas exchange rates, but also account for the age of carbon emitted, since this will impact the systems’ potential positive feedback effect on climate.

About the publication

This research was conducted by Frédéric Bouchard, Isabelle Laurion, and Vilmantas Prėskienis, of the INRS Eau Terre Environnement Research Centre, along with Daniel Fortier of Université de Montréal, Xiaomei Xu of University of California, and Michael J. Whiticar of University of Victoria. The resulting article, “Modern to millennium‐old greenhouse gases emitted from ponds and lakes of the Eastern Canadian Arctic (Bylot Island, Nunavut),” was recently published in the international journal Biogeosciences (DOI: 10.5194/bg-12-7279-2015). Financial support for the research team was provided by ArcticNet, the Natural Sciences and Engineering Research Council of Canada (NSERC), Natural Resources Canada’s Polar Continental Shelf Program, NSERC’s Discovery Frontiers and EnviroNorth programs, and the W. Garfield Weston Foundation. 

by Godin.E

New paper from N. Perreault et al. about vegetation transition following gullying

August 6, 2015 in Article, post by Godin.E

by Godin.E

New paper by Godin et al. on near surface dynamics in permafrost wetland following gully erosion

July 29, 2015 in Article, post by Godin.E

by Godin.E

New contribution from Frédéric Bouchard et al. on greenhouse gases emitted from fresh water ecosystems in the high Arctic

July 27, 2015 in Article, Paper by Godin.E