Arctic plant diversity in the Early Eocene greenhouse

For the majority of the Early Caenozoic, a remarkable expanse of humid, mesothermal to temperate forests spread across Northern Polar regions that now contain specialized plant and animal communities adapted to life in extreme environments. Little is known on the taxonomic diversity of Arctic floras during greenhouse periods of the Caenozoic. We show for the first time that plant richness in the globally warm Early Eocene (approx. 55–52 Myr) in the Canadian High Arctic (76° N) is comparable with that approximately 3500 km further south at mid-latitudes in the US western interior (44–47° N). Arctic Eocene pollen floras are most comparable in richness with today's forests in the southeastern United States, some 5000 km further south of the Arctic. Nearly half of the Eocene, Arctic plant taxa are endemic and the richness of pollen floras implies significant patchiness to the vegetation type and clear regional richness of angiosperms. The reduced latitudinal diversity gradient in Early Eocene North American plant species demonstrates that extreme photoperiod in the Arctic did not limit taxonomic diversity of plants.

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4. Polar marine biology

Marine Biology: A Very Short Introduction ◽

10.1093/actrade/9780198841715.003.0005 ◽

2020 ◽

pp. 71-86

Author(s):

Philip V. Mladenov

Keyword(s):

Climate Change ◽

Food Webs ◽

Marine Biology ◽

Extreme Environments ◽

The Arctic ◽

Polar Regions ◽

Light Levels ◽

The Arctic Ocean ◽

The Antarctic ◽

The Impact

Flourishing marine biological systems are present in the extreme environments of the Arctic and Antarctic polar regions of the planet. Both these regions are characterized by constantly cold sea temperatures, ice-covered oceans, and extreme seasonal fluctuations in light levels, but ‘Polar marine biology’ explains how they have evolved strikingly different and unique marine ecosystems. The Arctic Ocean is largely landlocked while the Southern Ocean surrounds the Antarctic continental land mass and is in open contact with the Atlantic, Indian, and Pacific oceans. The impact of human-induced climate change is also discussed, which will affect the Arctic and Antarctic food webs in profound ways.

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Photoperiodic induction without light-mediated circadian entrainment in a high arctic resident bird

10.1101/2020.06.19.160721 ◽

2020 ◽

Author(s):

Daniel Appenroth ◽

Vebjørn J. Melum ◽

Alexander C. West ◽

Hugues Dardente ◽

David G. Hazlerigg ◽

...

Keyword(s):

Activity Patterns ◽

High Arctic ◽

Gonadal Development ◽

Photoperiodic Response ◽

Day Length ◽

The Arctic ◽

Constant Light ◽

Constant Darkness ◽

Polar Regions ◽

Lagopus Muta

AbstractOrganisms use changes in photoperiod to anticipate and exploit favourable conditions in a seasonal environment. While species living at temperate latitudes receive day length information as a year-round input, species living in the Arctic may spend as much as two-thirds of the year without experiencing dawn or dusk. This suggests that specialised mechanisms may be required to maintain seasonal synchrony in polar regions.Svalbard ptarmigan (Lagopus muta hyperborea) are resident at 74-81° north latitude. They spend winter in constant darkness (DD) and summer in constant light (LL); extreme photoperiodic conditions under which they do not display overt circadian rhythms.Here we explored how arctic adaptation in circadian biology affects photoperiodic time measurement in captive Svalbard ptarmigan. For this purpose, DD-adapted birds, showing no circadian behaviour, either remained in prolonged DD, were transferred into a simulated natural photoperiod (SNP) or were transferred directly into LL. Birds transferred from DD to LL exhibited a strong photoperiodic response in terms of activation of the hypothalamic thyrotropin-mediated photoperiodic response pathway. This was assayed through expression of the Eya3, Tshβ and deiodinase genes, as well as gonadal development. While transfer to SNP established synchronous diurnal activity patterns, activity in birds transferred from DD to LL showed no evidence of circadian rhythmicity.These data show that the Svalbard ptarmigan does not require circadian entrainment to develop a photoperiodic response involving conserved molecular elements found in temperate species. Further studies are required to define how exactly arctic adaptation modifies seasonal timer mechanisms.Summary statementSvalbard ptarmigan show photoperiodic responses when transferred from constant darkness to constant light without circadian entrainment.

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Microscale drivers of summer CO2 fluxes in the Svalbard High Arctic tundra

Scientific Reports ◽

10.1038/s41598-021-04728-0 ◽

2022 ◽

Vol 12 (1) ◽

Author(s):

Marta Magnani ◽

Ilaria Baneschi ◽

Mariasilvia Giamberini ◽

Brunella Raco ◽

Antonello Provenzale

Keyword(s):

Ecosystem Respiration ◽

Vegetation Type ◽

Gross Primary Production ◽

Arctic Tundra ◽

High Arctic ◽

The Arctic ◽

Small Scale ◽

Arctic Ecosystems ◽

Additional Source ◽

And Storage

AbstractHigh-Arctic ecosystems are strongly affected by climate change, and it is still unclear whether they will become a carbon source or sink in the next few decades. In turn, such knowledge gaps on the drivers and the processes controlling CO2 fluxes and storage make future projections of the Arctic carbon budget a challenging goal. During summer 2019, we extensively measured CO2 fluxes at the soil–vegetation–atmosphere interface, together with basic meteoclimatic variables and ecological characteristics in the Bayelva river basin near Ny Ålesund, Spitzbergen, Svalbard (NO). By means of multi-regression models, we identified the main small-scale drivers of CO2 emission (Ecosystem Respiration, ER), and uptake (Gross Primary Production, GPP) in this tundra biome, showing that (i) at point scale, the temporal variability of fluxes is controlled by the classical drivers, i.e. air temperature and solar irradiance respectively for ER and GPP, (ii) at site scale, the heterogeneity of fractional vegetation cover, soil moisture and vegetation type acted as additional source of variability for both CO2 emissions and uptake. The assessment of the relative importance of such drivers in the multi-regression model contributes to a better understanding of the terrestrial carbon dioxide exchanges and of Critical Zone processes in the Arctic tundra.

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Differentiation of coarse-mode anthropogenic, marine and dust particles in the high Arctic Islands of Svalbard

10.5194/acp-2021-94 ◽

2021 ◽

Author(s):

Congbo Song ◽

Manuel Dall’Osto ◽

Angelo Lupi ◽

Mauro Mazzola ◽

Rita Traversi ◽

...

Keyword(s):

High Arctic ◽

The Arctic ◽

Dust Particles ◽

Sea Spray ◽

Polar Regions ◽

Long Distance ◽

Svalbard Archipelago ◽

Coarse Mode ◽

Arctic Haze ◽

Natural Aerosol

Abstract. Understanding aerosol-cloud-climate interactions in the Arctic is key to predict the climate in this rapidly changing region. Whilst many studies have focused on submicron aerosol (diameter less than 1 μm), relatively little is known about the climate relevance of supermicron aerosol (diameter above 1 μm). Here, we present a cluster analysis of multiyear (2015–2019) aerodynamic volume size distributions with diameter ranging from 0.5 to 20 μm measured continuously at the Gruvebadet Observatory in the Svalbard archipelago. Together with aerosol chemical composition data from several online and offline measurements, we apportioned the occurrence of the coarse-mode aerosols to anthropogenic (two sources, 27 %) and natural (three sources, 73 %) origins. Specifically, two clusters are related to Arctic haze with high levels of black carbon, sulfate and accumulation mode (0.1–1 μm) aerosol. The first cluster (9 %) is attributed to ammonium sulfate-rich Arctic haze particles, whereas the second one (18 %) to larger-mode aerosol mixed with sea salt. The three natural aerosol clusters were: open ocean sea spray aerosol (34 %), mineral dust (7 %), and an unidentified source of sea spray-related aerosol (32 %). The results suggest that sea spray-related aerosol in polar regions may be more complex than previously thought due to short/long-distance origins and mixtures with Arctic haze, biogenic and likely snow-blowing aerosols. Studying supermicron natural aerosol in the Arctic is imperative for understanding the impacts of changing natural processes on Arctic aerosol.

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Photoperiodic induction without light-mediated circadian entrainment in a High Arctic resident bird

Journal of Experimental Biology ◽

10.1242/jeb.220699 ◽

2020 ◽

Vol 223 (16) ◽

pp. jeb220699 ◽

Cited By ~ 1

Author(s):

Daniel Appenroth ◽

Vebjørn J. Melum ◽

Alexander C. West ◽

Hugues Dardente ◽

David G. Hazlerigg ◽

...

Keyword(s):

Activity Patterns ◽

High Arctic ◽

Gonadal Development ◽

Photoperiodic Response ◽

Day Length ◽

The Arctic ◽

Constant Darkness ◽

Polar Regions ◽

Natural Photoperiod ◽

Lagopus Muta

ABSTRACTOrganisms use changes in photoperiod to anticipate and exploit favourable conditions in a seasonal environment. While species living at temperate latitudes receive day length information as a year-round input, species living in the Arctic may spend as much as two-thirds of the year without experiencing dawn or dusk. This suggests that specialised mechanisms may be required to maintain seasonal synchrony in polar regions. Svalbard ptarmigan (Lagopus muta hyperborea) are resident at 74–81°N latitude. They spend winter in constant darkness (DD) and summer in constant light (LL); extreme photoperiodic conditions under which they do not display overt circadian rhythms. Here, we explored how Arctic adaptation in circadian biology affects photoperiodic time measurement in captive Svalbard ptarmigan. For this purpose, DD-adapted birds, showing no circadian behaviour, either remained in prolonged DD, were transferred into a simulated natural photoperiod (SNP) or were transferred directly into LL. Birds transferred from DD to LL exhibited a strong photoperiodic response in terms of activation of the hypothalamic thyrotropin-mediated photoperiodic response pathway. This was assayed through expression of the Eya3, Tshβ and deiodinase genes, as well as gonadal development. While transfer to SNP established synchronous diurnal activity patterns, activity in birds transferred from DD to LL showed no evidence of circadian rhythmicity. These data show that the Svalbard ptarmigan does not require circadian entrainment to develop a photoperiodic response involving conserved molecular elements found in temperate species. Further studies are required to define how exactly Arctic adaptation modifies seasonal timer mechanisms.

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Congruent responses to weather variability in high arctic herbivores

Biology Letters ◽

10.1098/rsbl.2012.0764 ◽

2012 ◽

Vol 8 (6) ◽

pp. 1002-1005 ◽

Cited By ~ 57

Author(s):

Audun Stien ◽

Rolf A. Ims ◽

Steve D. Albon ◽

Eva Fuglei ◽

R. Justin Irvine ◽

...

Keyword(s):

Life Histories ◽

Rangifer Tarandus ◽

Trophic Position ◽

High Arctic ◽

Climate Impact ◽

Climate Impacts ◽

The Arctic ◽

Polar Regions ◽

Arctic Ecosystems ◽

Wildlife Populations

Assessing the role of weather in the dynamics of wildlife populations is a pressing task in the face of rapid environmental change. Rodents and ruminants are abundant herbivore species in most Arctic ecosystems, many of which are experiencing particularly rapid climate change. Their different life-history characteristics, with the exception of their trophic position, suggest that they should show different responses to environmental variation. Here we show that the only mammalian herbivores on the Arctic islands of Svalbard, reindeer ( Rangifer tarandus ) and sibling voles ( Microtus levis ), exhibit strong synchrony in population parameters. This synchrony is due to rain-on-snow events that cause ground ice and demonstrates that climate impacts can be similarly integrated and expressed in species with highly contrasting life histories. The finding suggests that responses of wildlife populations to climate variability and change might be more consistent in Polar regions than elsewhere owing to the strength of the climate impact and the simplicity of the ecosystem.

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Spatiotemporal Analysis of Active Fires in the Arctic Region during 2001–2019 and a Fire Risk Assessment Model

Fire ◽

10.3390/fire4030057 ◽

2021 ◽

Vol 4 (3) ◽

pp. 57

Author(s):

Zhen Zhang ◽

Leilei Wang ◽

Naiting Xue ◽

Zhiheng Du

Keyword(s):

Risk Assessment ◽

Logistic Regression ◽

Vegetation Type ◽

Fire Risk ◽

Fire Frequency ◽

Assessment Model ◽

The Arctic ◽

Polar Regions ◽

Risk Assessment Model ◽

Fire Risk Assessment

The increasing frequency of active fires worldwide has caused significant impacts on terrestrial, aquatic, and atmospheric systems. Polar regions have received little attention due to their sparse populations, but active fires in the Arctic cause carbon losses from peatlands, which affects the global climate system. Therefore, it is necessary to focus on the spatiotemporal variations in active fires in the Arctic and to assess the fire risk. We used MODIS C6 data from 2001 to 2019 and VIIRS V1 data from 2012 to 2019 to analyse the spatiotemporal characteristics of active fires and establish a fire risk assessment model based on logistic regression. The trends in active fire frequency based on MODIS C6 and VIIRS V1 data are consistent. Throughout the Arctic, the fire frequency appears to be fluctuating and overall increasing. Fire occurrence has obvious seasonality, being concentrated in summer (June–August) and highest in July, when lightning is most frequent. The frequency of active fires is related to multiple factors, such as vegetation type, NDVI, elevation, slope, air temperature, precipitation, wind speed, and distances from roads and settlements. A risk assessment model was constructed based on logistic regression and found to be accurate. The results are helpful in understanding the risk of fires in the Arctic under climate change and provide a scientific basis for fire prediction and control and for reducing fire-related carbon emissions.

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Distinct Microbial Communities in Adjacent Rock and Soil Substrates on a High Arctic Polar Desert

Frontiers in Microbiology ◽

10.3389/fmicb.2020.607396 ◽

2021 ◽

Vol 11 ◽

Author(s):

Yong-Hoe Choe ◽

Mincheol Kim ◽

Yoo Kyung Lee

Keyword(s):

Microbial Community ◽

Microbial Communities ◽

Extreme Environments ◽

Chemical Properties ◽

Terrestrial Ecosystems ◽

High Arctic ◽

Polar Regions ◽

Polar Desert ◽

Arctic Soils ◽

Diversity Assessment

Understanding microbial niche variability in polar regions can provide insights into the adaptive diversification of microbial lineages in extreme environments. Compositions of microbial communities in Arctic soils are well documented but a comprehensive multidomain diversity assessment of rocks remains insufficiently studied. In this study, we obtained two types of rocks (sandstone and limestone) and soils around the rocks in a high Arctic polar desert (Svalbard), and examined the compositions of archaeal, bacterial, fungal, and protistan communities in the rocks and soils. The microbial community structure differed significantly between rocks and soils across all microbial groups at higher taxonomic levels, indicating that Acidobacteria, Gemmatimonadetes, Latescibacteria, Rokubacteria, Leotiomycetes, Pezizomycetes, Mortierellomycetes, Sarcomonadea, and Spirotrichea were more abundant in soils, whereas Cyanobacteria, Deinococcus-Thermus, FBP, Lecanoromycetes, Eurotiomycetes, Trebouxiophyceae, and Ulvophyceae were more abundant in rocks. Interestingly, fungal communities differed markedly between two different rock types, which is likely to be ascribed to the predominance of distinct lichen-forming fungal taxa (Verrucariales in limestone, and Lecanorales in sandstone). This suggests that the physical or chemical properties of rocks could be a major determinant in the successful establishment of lichens in lithic environments. Furthermore, the biotic interactions among microorganisms based on co-occurrence network analysis revealed that Polyblastia and Verrucaria in limestone, and Atla, Porpidia, and Candelariella in sandstone play an important role as keystone taxa in the lithic communities. Our study shows that even in niches with the same climate regime and proximity to each other, heterogeneity of edaphic and lithic niches can affect microbial community assembly, which could be helpful in comprehensively understanding the effects of niche on microbial assembly in Arctic terrestrial ecosystems.

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Body Temperature and Activity Rhythms Under Different Photoperiods in High Arctic Svalbard ptarmigan (Lagopus muta hyperborea)

Frontiers in Physiology ◽

10.3389/fphys.2021.633866 ◽

2021 ◽

Vol 12 ◽

Author(s):

Daniel Appenroth ◽

Andreas Nord ◽

David G. Hazlerigg ◽

Gabriela C. Wagner

Keyword(s):

Body Temperature ◽

Circadian Rhythms ◽

Core Body Temperature ◽

High Arctic ◽

The Arctic ◽

Constant Darkness ◽

Polar Regions ◽

Circadian Control ◽

Polar Day ◽

Lagopus Muta

Organisms use circadian rhythms to anticipate and exploit daily environmental oscillations. While circadian rhythms are of clear importance for inhabitants of tropic and temperate latitudes, its role for permanent residents of the polar regions is less well understood. The high Arctic Svalbard ptarmigan shows behavioral rhythmicity in presence of light-dark cycles but is arrhythmic during the polar day and polar night. This has been suggested to be an adaptation to the unique light environment of the Arctic. In this study, we examined regulatory aspects of the circadian control system in the Svalbard ptarmigan by recording core body temperature (Tb) alongside locomotor activity in captive birds under different photoperiods. We show that Tb and activity are rhythmic with a 24-h period under short (SP; L:D 6:18) and long photoperiod (LP; L:D 16:8). Under constant light and constant darkness, rhythmicity in Tb attenuates and activity shows signs of ultradian rhythmicity. Birds under SP also showed a rise in Tb preceding the light-on signal and any rise in activity, which proves that the light-on signal can be anticipated, most likely by a circadian system.

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Cloud observations at THAAO Observatory during the Arctic YOPP 2020

10.5194/egusphere-egu21-9114 ◽

2021 ◽

Author(s):

Giandomenico Pace ◽

Tatiana Di Iorio ◽

Alcide di Sarra ◽

Antonio Iaccarino ◽

Daniela Meloni ◽

...

Keyword(s):

Vertical Structure ◽

Climate Model ◽

Temporal Evolution ◽

High Arctic ◽

Surface Radiation ◽

The Arctic ◽

Polar Regions ◽

Liquid Water Path ◽

Large Uncertainty ◽

Radiation Fluxes

The radiative effects of clouds and their microphysical structure in Polar regions are still object of large uncertainty, that contribute to determine the large inaccuracies of climate model in the representation of clouds and their effects.In the frame of the CLouds And Radiation in the Arctic and Antarctica (CLARA2) project, a celiometer has been installed in November 2019 at the Thule High Arctic Atmospheric Observatory, THAAO, an international infrastructure located in proximity of Thule Air Base (76.5&#176;N, 68.8&#176;W), Greenland (http://www.thuleatmos-it.it/) with the aim of strengthening the cloud observational capability at the Observatory already including, among the other instruments, a microwave profiler and upward- and downward-looking pyranometers and pyrgeometers operating since July 2016.CLARA2 should have contributed to the YOPP 2020 Arctic Special Observing Period (SOP) in February-March with intensive measurements of the atmospheric vertical structure by means of a microwave profiler, a celiometer and daily radiosoundings, but the arrival of the COVID19 prevented the involved researchers to carry out the field campaign at THAAO. Nonetheless the automatic measurements were collected regularly also during the 2020 SOP.The temporal evolution of the cloud&#8217;s presence and characteristics during the two months SOP will be presented and discussed in terms of meteorological conditions, broadband surface radiation fluxes, cloud&#8217;s geometrical characteristics, phase and liquid water path.

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