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«Changing Polar Regions 25th International Congress on Polar Research March 17-22, 2013, Hamburg, Germany German Society for Polar Research Edited by ...»

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Our results indicate facilitation effects of the moss due to better seed survival in winter. Higher germination rate after winter leads to higher density and species richness of vascular plants in moss patches. Frost heaving did not appear to be strong, but might be an important factor for seedling survival. Our study shows the importance of facilitation in plant succession and emphasizes the widely underestimated role of mosses in ecosystems.

"Changing Polar Regions" - 25th International Congress on Polar Research 2013 NUTRIENTS (N & P) IN THE POLYGONAL TUNDRA – LIMITATIONS

AND AVAILABILITY

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Comparatively much is known about carbon pools and potential emissions from thawed permafrost soils (Tarnocai et al., 2009). However, other important macronutrients like nitrogen (N) and phosphorus (P) in permafrost soils are so far insufficiently investigated. Higher nutrient availability will enhance plant primary production which could partially offset higher CO2 emissions (Schuur et al., 2008).

Changes in the carbon budget of arctic ecosystems will have global implications (Sturm et al., 2005). Hence, a comprehensive knowledge about nutrient availability and potentially enhanced mobilization under changed climatic conditions is needed to

predict future development of arctic tundra. Open questions are:

How are soil nitrogen and phosphorus contents distributed within the • polygonal tundra landscapes?

What are the limiting factors for plant growth and microbial activity in the • polygonal tundra?

Which amounts of nutrients can be mobilized in the course of climate change?

• Methods Fieldwork has been conducted during two expeditions to north-eastern Siberia in the Indigirka lowlands as well as in the Kolyma lowlands.

Ten soil cores of 100cm and more have been drilled and were analyzed for their amounts of plant available Ammonium und Nitrate.

One single Ice-wedge polygon has been analyzed at a high detailed resolution (2*2m). To understand the limitation mechanisms at this site all soil profiles were analyzed for their amounts of plant available Nitrogen and Phosphorus, microbial Nitrogen and Phosphorus as well as total Nitrogen and Phosphorus. Additionally, also the according vegetation was analyzed for their total content of Nitrogen and Phosphorus.

In Arctic tundra is mainly limited by a low supply of Nitrogen. But furthermore it shows that there are large amounts of potentially available Nitrogen while largest parts of the total Phosphorus are recently an active part of the biogeochemical cycle.

In total, the concentration of plant available Ammonium in the frozen ground was seven times higher than in the active layer. The concentration of plant available Nitrate was lower than the concentration of plant available Ammonium. There were no significant differences between the concentrations of plant available Nitrate in the active layer and the frozen ground.

The results of the different nutrient pools (not shown) in the investigated polygon confirm that plant growth in Arctic tundra is mainly limited by a low supply of Nitrogen. But furthermore it shows that there are large amounts of potentially available Nitrogen while largest parts of the total Phosphorus are recently an active part of the biogeochemical cycle.

Conclusion We discover that there are large pools of potentially available Nitrogen in the active layer as well as in the permanently frozen ground of the polygonal tundra which could mitigate Nitrogen limitation of these areas in the course of projected climate change.

"Changing Polar Regions" - 25th International Congress on Polar Research 2013 ANALYSIS OF LONG-TERM ENVIRONMENTAL DATA FROM KING

GEORGE ISLAND (ANTARCTICA): RELATIONSHIPS BETWEEN

GLOBAL CLIMATIC OSCILLATIONS AND LOCAL SYSTEM

RESPONSE

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A long-term environmental data set from King George Island, Western Antarctic Peninsula, was analysed using statistical approaches that can deal with missing values. Since the WAP region belongs to the most rapidly warming regions on earth it is vital to find methods that take into account the incompleteness of Antarctic time series, but are still applicable to analyze general patterns in the series to arrive to conclusions on long term trends and inter-annual variability in the face of the rapidly changing climate in Western Antarctica. We applied U statistics after Pettit and Buishand to detect sudden changes over time, a dynamic factor analysis as well as additive modelling to detect common trends and patterns related to climatic cycles such as the Southern Annular Mode and El Niño Southern Oscillation. Our results not only reveal sudden changes for sea surface temperature and salinity, but also clear patterns in all investigated variables (sea surface temperature, salinity, suspended particulate matter and Chlorophyll a) that can be directly be assigned to climatic cycles. Hence, our statistical analyses may prove valuable for other polar environmental data sets and contribute to a better understanding of the regional variability of climate change and its impact on coastal systems.

"Changing Polar Regions" - 25th International Congress on Polar Research 2013 ICE RISE INVENTORY USING HIGH-RESOLUTION TERRASAR-X

IMAGERY





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Ice rises play a key role in the stability of unbounded ice shelves and they often determine the shape of the calving front. Grounding lines around ice rises and ice shelves retreat when sea level rises. Ungrounding may causes a destabilizing situation and promotes disintegration of ice shelves. Located in the interior of an ice shelf, they cause different effects: (1) For a long time they are supposed to stabilize ice shelves, as they act as pinning points located at the ice front. (2) The ice shelf around ice rises is often a genesis of inhomogeneities. They could be made up of discontinuous mass which play an important role in ice shelf dynamics. (3) Ice rises are also a well known feature for formation of failure zones (rifts). In the absence of a compressive stress zone that hinders rift propagation, they have a destabilizing factor.

The work presented aims to build up an inventory for ice rises. Therefore, highresolution radar imagery of the TerraSAR-X are used to classify ice rises over most of the Antarctic ice shelves. This is done with respect of their contribution to buttress inland ice masses, the kind of inhomogeneities they cause and whether they determine the calving front position. This study is concentrated to smaller ice rises which are particularly prone to ungrounding under rising sea level. The newly detected ice rises will be included and classified in an ice rise inventory. In order to prove the detection and classification remotely sensed surface elevations (e.g.

ICESat GLAS) and surface velocities (e.g. Radarsat-1 (MAMM) and MEaSUREs InSAR) will be used as ice rises cause small scale variations in both fields.

"Changing Polar Regions" - 25th International Congress on Polar Research 2013 ERKUNDUNG TEMPERIERTER GLETSCHER DES NÖRDLICHEN

PATAGONISCHEN EISFELDS MIT HELIKOPTER-RADAR

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Messungen an tiefen temperierten Gletschern mit Helikopter-GPR sind aufgrund von hoher Absorption, interner Streuung und der Rauigkeit von Oberfläche und Felsbett sehr anspruchsvoll. Nur bei niedrigen Mittenfrequenzen lassen sich die Streu- und Rauigkeitseffekte so weit reduzieren, dass Radardaten guter Qualität gewonnen werden.

Das nördliche patagonische Eisfeld (Campo de Hielo Norte) in Chile ist ein Rest des einstigen patagonischen Eisschildes mit immer noch beeindruckend großen Auslassgletschern, deren Geometrie bislang nur unzureichend bekannt ist. Von diesen untersuchten wir im Jahr 2010 die am östlichen Rand liegenden Glaciar Nef und Glaciar Colonia auf ca. 220 Profilkilometern mit dem 30MHz-Helikopter-Radarsystem der BGR.

Die Oberflächen der zwei bis drei Kilometer breiten und 20 km langen Gletscher zeigen ausgedehnte Zonen mit Spalten, Schmelzwasser und Moränenmaterial. Die Geometrie beider Eiskörper kann trotz dieser messtechnischen Schwierigkeiten in den beflogenen unteren Bereichen gut abgebildet werden. Eisdicken und Eindringtiefen im Untersuchungsgebiet erreichen maximal 700 m.

"Changing Polar Regions" - 25th International Congress on Polar Research 2013 MODELLING HABITAT SUITABILITY OF HUMPBACK AND

ANTARCTIC MINKE WHALES IN THE SOUTHERN OCEAN

Annette Bombosch, Ilse Alfred-Wegener-Institut van Opzeeland, Daniel P. Helmholtz-Zentrum für Polar- und Zitterbart, Mary S. Wisz, Meeresforschung, Bremerhaven,

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Monitoring the recovery of cetacean stocks in the Southern Ocean has been at the core of IWC (International Whaling Commission) activities during the past three decades. However, collecting data in the Southern Ocean is particularly difficult due to the region’s remoteness, limited seasonal accessibility and presence of sea ice. As a result, distribution patterns and cetacean-habitat preferences, which are necessary to properly design population surveys for robust stock assessments, are still insufficiently described.

Early attempts to study habitat preferences of cetaceans in the Southern Ocean used descriptive techniques, such as overlaying cetacean sightings with maps of habitat variables and simple correlation analyses. Increasing availability of remotely sensed environmental data and recent advances in habitat modelling techniques now provide the necessary data and tools to perform more sophisticated analyses of habitat requirements. While most habitat models developed for the Southern Ocean rely on presence-absence data from line-transect surveys, latest improvements of modelling algorithms extent their applicability to presence-only data.

We developed habitat models for humpback (Megaptera novaeangliae) and Antarctic minke whales (Balaenoptera bonaerensis) using ship-based presence-only data.

Cetacean sightings have been collected opportunistically, but were systematically logged by the nautical officers on board the research icebreaker Polarstern during expeditions to the Southern Ocean since 2005. A custom-built software tool “WALOG” was used to ensure a standardized protocol to log cetacean sightings and associated metadata. To develop habitat models, we used a maximum entropy approach, called Maxent, which was specifically designed to analyse presence-only data. Environmental parameters used in the model included both static variables, such as depth or slope, and dynamic variables, such as sea surface temperature or sea ice concentration, at a daily resolution. To account for spatial bias potentially inherent in the data, we used 10,000 randomly selected background locations from the cruise tracks to describe the environmental conditions as encountered throughout the study area. Sample sizes of cetacean sightings allowed the development of habitat models for humpback whales (N=93) during austral summer and two separate habitat models for minke whales during austral summer (N=139) and winter (N=44) to investigate potential inter-annual differences in minke whale habitat preferences.

"Changing Polar Regions" - 25th International Congress on Polar Research 2013 Overall differences between the two species revealed more northern habitat preferences for humpback whales within ice free areas, whereas minke whales featured a higher habitat affinity further to the South. Throughout the summer season, however, habitat suitability for humpback whales increased southwards towards the Antarctic continent. Habitat suitability for either species was furthermore not homogeneously distributed throughout the Southern Ocean, but several distinct areas of high habitat suitability were identified.

"Changing Polar Regions" - 25th International Congress on Polar Research 2013 ANDEEP-SYSTCO (SYSTEM COUPLING): CONTRIBUTIONS TO THE

BIODIVERSITY AND FEEDING BIOLOGY OF SOUTHERN OCEAN

DEEP-SEA BENTHOS

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ANDEEP – SYSTCO builds on the close cooperation of scientists from different disciplines, such as physical oceanography, planktology, biogeochemistry, sedimentology, and bathymetry with benthologist concentrating on various aspects to shed light on atmospheric-pelagic-benthic coupling processes.

SYSTCO investigates a) the diversity, distribution and abundance of deep-sea organisms from meiofaunal foraminifera to megafaunal organisms in relation to the surface water productivity, sediment composition and biogeochemistry of the sediment-water interface as well as the upper sediment layer, and b) the ecology of deep-sea fauna with regard to coupling processes utilizing different approaches, like classical gut content analyses as well as biochemical investigations (fatty acid profiles and stable isotope C and N ratios).

"Changing Polar Regions" - 25th International Congress on Polar Research 2013 UPWELLING IN THE WEDDELL SEA INFERRED FROM HELIUM

ISOTOPE DISEQUILIBRIUM

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Upwelling plays an important role regarding the physical and biogeochemical characteristics of the mixed layer, and it may also counteract the uptake of atmospheric gases like CO2. However, estimates of upwelling velocities are rare, particularly in the Antarctic Ocean. Since upwelling velocities are too small to be measured directly - approximately a few meters per day - an indirect method to infer upwelling velocities from the helium isotope disequilibrium in the mixed layer is applied here instead. Helium isotope data measured during austral summer 2010/11 in the Weddell Sea and south of 57°S along the Greenwich Meridian show a significant excess of 3He in the mixed layer. The influence of the prevailing wind fields and the ice coverage is studied and first results will be presented.

"Changing Polar Regions" - 25th International Congress on Polar Research 2013 ANTARKTIKA IST EIN KONTINENT UND EWIGES EIS NUR DEM

NAMEN NACH EWIG! IDEEN ZUR GESTALTUNG DES UNTERRICHTS ZU DEN POLARGEBIETEN AUF BASIS VON SCHÜLERVORSTELLUNGEN ZUR KALTEN ZONE

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