GeoLog

Patagonia

Imaggeo on Mondays: The unique bogs of Patagonia

Imaggeo on Mondays: The unique bogs of Patagonia

Patagonia, the region in southernmost tip of South America, is as diverse as it is vast. Divided by the Andes, the arid steppes, grasslands and deserts of Argentina give way to the temperate rainforests, fjords and glaciers of Chile. Also on the Chilean side are rolling hills and valleys of marshy topography: Patagonia’s bogs. Today, Klaus-Holger Knorr, a researcher at the University of Münster’s Institute for Landscape Ecology, tells us about what makes these peatlands so unique.

This picture shows an ombrotrophic, oceanic bog at the Seno Skyring Fjord, Patagonia, Chile. It is a view from the inner part of the peatland south toward the shore of the Fjord, in the background Isla Escapada and the Gran Campo ice field. Ombrotrophic bogs are peatlands (accumulations of more or less decomposed plant material which collect in a water-saturated environment) receiving their water and nutrients solely from the atmosphere, i.e. by rain, wet and dry deposition.

Similar to their Northern counterparts in Canada, Northern US, Fennoscandia or Siberia, these southern Patagonian peatlands  formed after the last deglaciation and accumulated huge amounts of carbon as peat.

Peatlands cover only about 3 % of the global land surface but store about a third of the soil carbon pool. Peat is formed primarily as there is excess rainfall, peat soils are water logged, oxygen gets depleted, and decomposition is limited. Pristine, undisturbed peatlands can store as much as 10-50 g carbon per square meter and year.

What makes the peatlands in Patagonia  particularly interesting  is their pristine, undisturbed conditions and extremely low input of nutrients from the atmosphere, compared to the high input into sites in densely settled or industrial regions. This allows studies of peatland functioning under natural conditions and absence of anthropogenic impacts.

Moreover, peatlands in Patagonia harbor a specific kind of vegetation, including cushion forming plants such as Astelia pumila and Donatia fascicularis. These cushion forming plants have a very low above ground biomass but an extremely large rooting system, reaching down to a depth of >2 m in case of A. pumila. As these roots act as conduits for oxygen to sustain viability of the roots in the water logged peat, they have been shown to aerate large parts even of the saturated zone, thereby impeding high methane production and emission. Oxygen supply by these roots is even hypothesized to stimulate peat decomposition and thereby lead to particularly decomposed peat under cushion plant cover.

Another plant species only occurring in peatlands of Southern Patagonia, a small conifer named Lepidothamnus fonkii, has developed a particular strategy to overcome nutrient deficiency: it has formed a close association with bacteria being able fix atmospheric nitrogen to fulfill the demand of nitrogen for growth. While such nitrogen fixation is well known for legumes and some tree species, it has rarely been found for conifers.

A further important factor for peatlands in Patagonia, leading to the term “oceanic bogs”, is the fact that these peatlands in close vicinity to the seashore receive high inputs of sea salts from sea spray, modifying availability of associated elements such as Sodium, Calcium, Magnesium, Sulphur and others.

By Klaus-Holger Knorr, researcher at the University of Münster’s Institute for Landscape Ecology

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: Late Holocene Fever

Imaggeo on Mondays: Late Holocene Fever

A huge ice fall off the Perito Moreno glacier in the Los Glaciares National Park, southwest Santa Cruz Province, Argentina, was voted one of the three best pictures entered into the EGU’s annual photo contest, by the conference participants at the 2015 General Assembly.

Perito Moreno glacier is one of 48 glaciers feeding into the Southern Patagonia ice field, which combined with the Northern Patagonia ice field, comprise the largest temperate ice mass in the Southern Hemisphere. Like many other mountain glaciers, Perito Moreno, is highly sensitive to climate change. At the surface of a glacier, erosive processes know as ablation, can remove ice from the bulk of the glacial mass. If the ice lost is not replaced in sufficient quantities by rainfall and snow provided by weather systems, the energy balance of the glacier is upset and the glacier starts to shrink. At the glacial surface, the processes of accumulation and ablation, clearly manifest the strict connection between glaciers and climate.

In a recent interview, Bernard Francou, a renowned French glaciologist, explained that glacier depletion in the Andes region has increased dramatically in the second half of the 20th century. In recent decades the glacier recession rates increased at an unprecedented rate when compared to the last the last three centuries. It is estimated that glaciers in this region have lost between 35% and 50% of their area and volume since 1976.

Christian Massari, a hydrology postdoctoral researcher of the Italian National Research Council, says “capturing the precise moment when the large chunk of ice broke off the glacier front was not easy task. It required concentration to patiently wait two hours, on a hot January day, to capture the critical moment.”

You can watch a video of a similar ice fall event, which took place in January 2012, here.

Southern Patagonia Ice Field. Credit: Astronaut photograph ISS038-E-47324 was acquired on February 13, 2014, with a Nikon D3S digital camera using a 65 millimeter lens, and is provided by the ISS Crew Earth Observations Facility and the Earth Science and Remote Sensing Unit, Johnson Space Center. The image was taken by the Expedition 38 crew. It has been cropped and enhanced to improve contrast, and lens artifacts have been removed.

Southern Patagonia Ice Field . Credit: Astronaut photograph ISS038-E-47324 was acquired on February 13, 2014, with a Nikon D3S digital camera using a 65 millimeter lens, and is provided by the ISS Crew Earth Observations Facility and the Earth Science and Remote Sensing Unit, Johnson Space Center. The image was taken by the Expedition 38 crew. It has been cropped and enhanced to improve contrast, and lens artifacts have been removed. (Distributed via Nasa Earth Observatory, Image of the Day ).

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/.