GeoLog

Canada

Imaggeo on Mondays: Patterns in the peatland

Imaggeo on Mondays: Patterns in the peatland

This magnificent pattern is the result of hundreds and hundreds of years of evolution. In this structured minerotrophic peatland in Northern Quebec (Canada), which can also be called a string fen or aapa mire, the green peat ridges (or strings) alternate with water-filled hollows (or flarks). Often flarks are replaced by ponds, which vary in number and size. This pattern of strings and flarks (or ponds) runs perpendicular to the flow of ground water.

Many theories exist to explain the dynamics of this pattern; however, we still do not know the mechanism responsible. Almost all of the present theories suggest that the movement of water could be a major driver of the landscape’s features. The permafrost and frost action, the gradual down-slope slipping, and expansion of peat, the merging of hollows, and fire outbreaks are also considered to be potential factors. Further research is going on to deeply understand the complex relation between abiotic and biotic factors influencing how the string fens take shape.

Vegetation in string fens differs between strings and flarks. Strings are dominated by sedges like Carex exilis, Trichophorum cespitosum, Eriophorum angustifolium, and dwarf birches (Betula glandulosa). On the other hand, flarks or ponds are dominated by Menyanthes trifoliata (also known as bogbean), depending on the level of the water within the ground. The peat moss Sphagnum subfulvum is found on strings while a different species of moss Sphagnum majus can be found on floating mats, at the margin of ponds.

This type of peatland is abundant in the boreal regions of the world, and its predominance can be explained by cooler weather conditions, that limit Sphagnum growth and foster greater surface water flow, especially when the snow melts in the spring.

I encountered this beauty on a field trip during summer of 2016 when I was looking for fens burned by natural wildfires. Unfortunately (or not) this one did not burn, even though all the forests at the margin of the peatland burned pretty heavily. Indeed, the ground of the burned forests was covered by Polytrichum strictum, a pioneer moss known to colonize burned forests or peatland soils (look for the apple green vegetation in the bottom of the photograph).

By Mélina Guêné-Nanchen, Laval University, Québec, Canada

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

Imaggeo on Mondays: A modern cliff hides ancient dunes

Imaggeo on Mondays: A modern cliff hides ancient dunes

Ancient sand dunes exposed off a cliff face on the shoreline of Nova Scotia at the Islands Provincial Park. The juxtaposition of the high angled strata and flat lying layers above revels the drastic change in climate in Nova Scotia’s history; from vast sand dunes to a calm lake system, and presently the western coastline of the Atlantic Ocean.

Description by Robert Wu, as it first appeared on imaggeo.egu.eu.

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

Imaggeo on Mondays: Wildfires leave their mark on Jasper National Park

Imaggeo on Mondays: Wildfires leave their mark on Jasper National Park

Jasper National Park is the largest national park in the Canadian Rocky Mountains, spanning across nearly 11,000 square kilometres of Canadian wilderness. The park is known for its rugged landscape, extensive trails, and abundance of deer, bighorn sheep, wolves, mountain lions and bears. This region is also very susceptible to blazing wildfires, a result of human activity that began more than a century ago.

This black bear came down from the forest on the left side, a few minutes after Ziesch took the photo of the lake. Credit: Jennifer Ziesch

In 1909, just two years after the park was established, the first national park wardens were hired to extinguish wildfires. At the time, all man-made and natural fires were considered threats to the forest and its inhabitants.

However, ecologists now know that fires are in fact a natural part of Canada’s forest dynamics and play an important role in shaping the diversity and ecology of these regions.

By suppressing natural fires, the park wardens had a hand in limiting the diversity of plants and animals in these forests, making the landscape more prone to insect infestation and disease. This in turn increases the chance of sparking large threatening wildfires.

For example, Jasper National Park has for some time been plagued by mountain pine beetles, with foresters reporting a tenfold increase in beetle infection along the park’s perimeter. The insects bore into the wood and after two to three years, leave behind dry dead trees, the perfect kindling for big wildfires.

July 2015, one particularly chaotic wildfire, ignited by a lightning strike, consumed 1,000 hectares of the Maligne Valley area in central Jasper National Park. At one point, the wildfire was only 15 kilometres from the local town Jasper, but fortunately the wind redirected the fire’s path. If not for the fire’s change in direction, 50,000 people would have been forced evacuate their homes. After four days, cooler temperatures and six milimetres of rain gave wildfire management crews the opportunity to control and suppress the flames. Additionally, a small plateau that was unusually moist stopped the fire from burning up the slopes on the west side of Medicine Lake, dramatically reducing the fire’s overall size.

Jennifer Ziesch, a researcher at the Federal Institute for Geosciences and Natural Resources in Germany, took this featured photograph of Medicine Lake last year when road tripping with her husband through the US and Canadian Rocky Mountains.

“It was only after I glanced at the photo twice that I noticed its importance. On the right side, you can see the burnt forest, where the wildfire stopped” said  Ziesch.

“The contrast between the charred black versus the vibrant green and the scorched red tells a powerful story about forest resilience and renewal. Even now, three years later on, you can still see the consequences of the wildfire, but the natural equilibrium is slowly returning.”

References

A look back at Jasper park’s Excelsior wildfire (The Fitzhugh)

Fire and vegetation management in the Mountain National Parks, Parks Canada

Increased wildfire risk in Jasper due to pine beetles, says MP (Global News)

Jasper National Park not prepared for potential forest fire ‘catastrophe,’ researchers say (CBC)

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

Imaggeo on Mondays: Iceberg viewing in Cape Spear, Newfoundland, Canada

Imaggeo on Mondays: Iceberg viewing in Cape Spear, Newfoundland, Canada

Cape Spear in Newfoundland, Canada is the easternmost location in North America and one of the few places in the world where you can contemplate icebergs from the shore. Every year, about 400 to 800 bergs journey down to this particular point. These 10,000-year-old ice giants drift along the northern shore of Newfoundland with the Labrador Current.

About 90 percent of these icebergs come from western Greenland glaciers, where they break off directly into Baffin Bay. Often these bergs remain in the bay for several years, preserved by the cold arctic waters and circulating along with local currents. Eventually, many icebergs escape through the Davis Strait, drifting down the Labrador Current and passing through Iceberg Alley to reach the Grand Banks of Newfoundland, the region of the North American continental shelf where Cape Spear is situated. This journey from Greenland to the Grand Banks usually takes between two and three years.

Cape Spear is just a few kilometres from Newfoundland’s largest city, St. John’s, and attracts many tourists during spring and early summer months to enjoy the immense icebergs. The chances of seeing them depend greatly on the temperature, wind direction, ocean currents and amount of sea ice during the winter, which protects icebergs from erosion. The icebergs have a great impact on Newfoundland’s identity and economy, bringing tourists and even giving breweries unique ice for beer and liquor production.

On the other hand, the floating ice can be a hazard to oil platforms and cargo boats. Smaller bergs can be especially hazardous since they are harder to detect with marine radar. If deep enough, the icebergs can also damage seabed structures like pipelines and cables. Thus, it is important to keep monitoring the dynamics of icebergs, especially since there will likely be a greater volume of ice breaking from the Greenland glaciers and drifting in the North Atlantic due to climate change.

By Simon Massé, PhD student, Université du Québec à Rimouski, Canada

References

Barber, D.G., Babb, D.G., Ehn, J.K., Chan,W., Matthes, L., Dalman, L. A., et al.: Increasing mobility of high Arctic Sea ice increases marine hazards off the east coast of Newfoundland, Geophysical Research Letters, 45,2370–2379, https://doi.org/10.1002/2017GL076587, 2018.

Diemand, D., Icebergs, Encyclopedia of Ocean Sciences, 3: 1255-1264,  2001.

Iceberg Finder, Icebergs Facts. Newfoundland & Labrador Tourism, 2012.

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.