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K Sokolowska, M Turzanska, M-C Nilsson
Background and Aims: The ubiquitous feather mosses Pleurozium schreberi and Hylocomium splendens form a thick, continuous boundary layer between the soil and the atmosphere, and play important roles in hydrology and nutrient cycling in tundra and boreal ecosystems. The water fluxes among these mosses and environmental factors controlling them are poorly understood. The aim of this study was to investigate whether feather mosses are capable of internal transport and to provide a better understanding of species-specific morphological traits underlying this function...
September 28, 2017: Annals of Botany
Ann Milbau, Nicolas Vandeplas, Fred Kockelbergh, Ivan Nijs
Climate change is expected to force many species in arctic regions to migrate and track their climatic niche. This requires recruitment from seed, which currently shows very low rates in arctic regions, where long-lived and vegetatively reproducing plants dominate. Therefore, we pose the question whether recruitment (germination and seedling establishment) in arctic regions will significantly improve in a warmer world, and thus allow species to follow their climatic niche. We used a full factorial experiment to examine if realistic warmer temperatures (+3 °C; infrared radiation) and increased nitrogen availability (+1...
September 2017: AoB Plants
Ziming Yang, Sihang Yang, Joy D Van Nostrand, Jizhong Zhou, Wei Fang, Qi Qi, Yurong Liu, Stan D Wullschleger, Liyuan Liang, David E Graham, Yunfeng Yang, Baohua Gu
Microbial decomposition of soil organic carbon (SOC) in thawing Arctic permafrost is important in determining greenhouse gas feedbacks of tundra ecosystems to climate. However, the changes in microbial community structure during SOC decomposition are poorly known. Here we examine these changes using frozen soils from Barrow, Alaska, USA, in anoxic microcosm incubation at -2 and 8°C for 122 days. The functional gene array GeoChip was used to determine microbial community structure and the functional genes associated with SOC degradation, methanogenesis, and Fe(III) reduction...
2017: Frontiers in Microbiology
Xiaolong Wang, Lin Li, Wei Zhao, Jiaxin Zhao, Xia Chen
Rhododendron aureum Georgi is a perennial evergreen dwarf shrub that grows at all elevations within the alpine tundra of northern China. Previous research has investigated the plant communities of R. aureum; however, little information is available regarding interspecific competition and underground soil microbial community composition. The objective of our study was to determine whether the presence of R. aureum creates a unique soil microbiome and to investigate the relationship between R. aureum and other plant species...
September 2017: Ecology and Evolution
Yao Huang, Ziyan Wei, Wangmu Danzeng, Myong Chol Kim, Guoxin Zhu, Yumin Zhang, Zuobing Liu, Fang Peng
Strain 200T, isolated from a soil sample taken from Antarctic tundra soil around Zhongshan Station, was found to be a Gram-stain-negative, yellow-pigmented, catalase-positive, oxidase-negative, non-motile, non-spore-forming, rod-shaped and aerobic bacterium. Strain 200T grew optimally at pH 7.0 and in the absence of NaCl on R2A. Its optimum growth temperature was 20 °C. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain 200T belonged to the genus Sphingomonas. Strain 200T showed the highest sequence similarities to Sphingomonas kyeonggiense THG-DT81T (95...
September 21, 2017: International Journal of Systematic and Evolutionary Microbiology
David G Long
Wind scatterometers were originally developed for observation of near-surface winds over the ocean. They retrieve wind indirectly by measuring the normalized radar cross section (σ(o) ) of the surface, and estimating the wind via a geophysical model function relating σ(o) to the vector wind. The σ(o) measurements have proven to be remarkably capable in studies of the polar regions where they can map snow cover; detect the freeze/thaw state of forest, tundra, and ice; map and classify sea ice; and track icebergs...
May 2017: IEEE J Sel Top Appl Earth Obs Remote Sens
Dorothee Ehrich, Maite Cerezo, Anna Y Rodnikova, Natalya A Sokolova, Eva Fuglei, Victor G Shtro, Aleksandr A Sokolov
BACKGROUND: High latitude ecosystems are at present changing rapidly under the influence of climate warming, and specialized Arctic species at the southern margin of the Arctic may be particularly affected. The Arctic fox (Vulpes lagopus), a small mammalian predator endemic to northern tundra areas, is able to exploit different resources in the context of varying tundra ecosystems. Although generally widespread, it is critically endangered in subarctic Fennoscandia, where a fading out of the characteristic lemming cycles and competition with abundant red foxes have been identified as main threats...
September 16, 2017: BMC Ecology
Alistair Rogers, Shawn P Serbin, Kim S Ely, Victoria L Sloan, Stan D Wullschleger
Terrestrial biosphere models (TBMs) are highly sensitive to model representation of photosynthesis, in particular the parameters maximum carboxylation rate and maximum electron transport rate at 25°C (Vc,max.25 and Jmax.25 , respectively). Many TBMs do not include representation of Arctic plants, and those that do rely on understanding and parameterization from temperate species. We measured photosynthetic CO2 response curves and leaf nitrogen (N) content in species representing the dominant vascular plant functional types found on the coastal tundra near Barrow, Alaska...
September 6, 2017: New Phytologist
Kari Anne Bråthen, Virve Tuulia Ravolainen, Audun Stien, Torkild Tveraa, Rolf A Ims
Rangifer (caribou/reindeer) management has been suggested to mitigate the temperature-driven transition of arctic tundra into a shrubland state, yet how is uncertain. Here we study this much focused ecosystem state transition in riparian areas, where palatable willows (Salix) are dominant tall shrubs and highly responsive to climate change. For the state transition to take place, small life stages must become tall and abundant. Therefore we predicted that the performance of small life stages (potential recruits) of the tall shrubs were instrumental to the focal transition, where Rangifer managed at high population density would keep the small-stage shrubs in a "browse trap" independent of summer temperature...
September 4, 2017: Ecological Applications: a Publication of the Ecological Society of America
Elina Kaarlejärvi, Anu Eskelinen, Johan Olofsson
Climate warming is altering the diversity of plant communities but it remains unknown which species will be lost or gained under warming, especially considering interactions with other factors such as herbivory and nutrient availability. Here, we experimentally test effects of warming, mammalian herbivory and fertilization on tundra species richness and investigate how plant functional traits affect losses and gains. We show that herbivory reverses the impact of warming on diversity: in the presence of herbivores warming increases species richness through higher species gains and lower losses, while in the absence of herbivores warming causes higher species losses and thus decreases species richness...
September 4, 2017: Nature Communications
Jan Heggenes, Arvid Odland, Tomas Chevalier, Jörgen Ahlberg, Amanda Berg, Håkan Larsson, Dag K Bjerketvedt
Mammalian herbivores have important top-down effects on ecological processes and landscapes by generating vegetation changes through grazing and trampling. For free-ranging herbivores on large landscapes, trampling is an important ecological factor. However, whereas grazing is widely studied, low-intensity trampling is rarely studied and quantified. The cold-adapted northern tundra reindeer (Rangifer tarandus) is a wide-ranging keystone herbivore in large open alpine and Arctic ecosystems. Reindeer may largely subsist on different species of slow-growing ground lichens, particularly in winter...
August 2017: Ecology and Evolution
Mads Forchhammer
Measures of increased tundra plant productivity have been associated with the accelerating retreat of the Arctic sea-ice. Emerging studies document opposite effects, advocating for a more complex relationship between the shrinking sea-ice and terrestrial plant productivity. I introduce an autoregressive plant growth model integrating effects of biological and climatic conditions for analysing individual ring-width growth time series. Using 128 specimens of Salix arctica, S. glauca and Betula nana sampled across Greenland to Svalbard, an overall negative effect of the retreating June sea-ice extent was found on the annual growth...
August 2017: Biology Letters
Irina S Kulichevskaya, Anastasia A Ivanova, Ekaterina N Detkova, W Irene C Rijpstra, Jaap S Sinninghe Damsté, Svetlana N Dedysh
Two strains of aerobic, budding, pink-pigmented bacteria, P12T and P515, were isolated from a lichen-dominated peatland and a forested tundra soil of north-western Siberia, respectively. Cells of these isolates were represented by non-motile spheres that occurred singly or were arranged in short chains and aggregates. While growing on solid media, cells of strains P12T and P515 attached to the surface by means of holdfast-like appendages. These isolates were mildly acidophilic (optimum growth at pH 5.5-6.0), psychrotolerant bacteria, which displayed tolerance of low temperatures (4-15 °C), grew optimally at 15-22 °C and did not grow at temperatures above 28 °C...
September 2017: International Journal of Systematic and Evolutionary Microbiology
Marc Macias-Fauria, Stein Rune Karlsen, Bruce C Forbes
The rapid decline in Arctic sea ice poses urgent questions concerning its ecological effects, such as on tundra terrestrial productivity. However, reported sea ice/terrestrial productivity linkages have seldom been constrained, and the mechanism governing them remains elusive, with a diversity of spatial scales and metrics proposed, at times in contradiction to each other. In this study, we use spatially explicit remotely sensed sea ice concentration and high-resolution terrestrial productivity estimates (Normalised Difference Vegetation Index, NDVI) across the Svalbard Archipelago to describe local/sub-regional and large-scale components of sea ice/terrestrial productivity coupling...
August 17, 2017: Scientific Reports
Hajime Ikeda, Pernille Bronken Eidesen, Valentin Yakubov, Vyacheslav Barkalov, Christian Brochmann, Hiroaki Setoguchi
The circumarctic ranges of arctic-alpine plants are thought to have been established in the late Pliocene/early Pleistocene, when the modern arctic tundra was formed in response to climate cooling. Previous findings of range-wide genetic structure in arctic-alpine plants have been thought to support this hypothesis, but few studies have explicitly addressed the temporal framework of the genetic structure. Here, we estimated the demographic history of the genetic structure in the circumarctic Kalmia procumbens using sequences of multiple nuclear loci and examined whether its genetic structure reflects prolonged isolation throughout the Pleistocene...
August 16, 2017: Molecular Ecology
Mengting M Yuan, Jin Zhang, Kai Xue, Liyou Wu, Ye Deng, Jie Deng, Lauren Hale, Xishu Zhou, Zhili He, Yunfeng Yang, Joy D Van Nostrand, Edward A G Schuur, Konstantinos T Konstantinidis, C Ryan Penton, James R Cole, James M Tiedje, Yiqi Luo, Jizhong Zhou
Permafrost soil in high latitude tundra is one of the largest terrestrial carbon (C) stocks and is highly sensitive to climate warming. Understanding microbial responses to warming induced environmental changes are critical to evaluating their influences on soil biogeochemical cycles. In this study, a functional gene array (i.e. GeoChip 4.2) was used to analyze the functional capacities of soil microbial communities collected from a naturally degrading permafrost region in Central Alaska. Varied thaw history was reported to be the main driver of soil and plant differences across a gradient of minimally, moderately and extensively thawed sites...
July 17, 2017: Global Change Biology
Daniel Obrist, Yannick Agnan, Martin Jiskra, Christine L Olson, Dominique P Colegrove, Jacques Hueber, Christopher W Moore, Jeroen E Sonke, Detlev Helmig
Anthropogenic activities have led to large-scale mercury (Hg) pollution in the Arctic. It has been suggested that sea-salt-induced chemical cycling of Hg (through 'atmospheric mercury depletion events', or AMDEs) and wet deposition via precipitation are sources of Hg to the Arctic in its oxidized form (Hg(ii)). However, there is little evidence for the occurrence of AMDEs outside of coastal regions, and their importance to net Hg deposition has been questioned. Furthermore, wet-deposition measurements in the Arctic showed some of the lowest levels of Hg deposition via precipitation worldwide, raising questions as to the sources of high Arctic Hg loading...
July 12, 2017: Nature
Bronisław Wojtuń, Aleksandra Samecka-Cymerman, Ludwik Żołnierz, Adam Rajsz, Alexander J Kempers
Calluna vulgaris, Carex rigida, Deschampsia flexuosa, Nardus stricta and Vaccinium myrtillus are abundant in the vegetation of mountainous areas in Northern and Central Europe. Knowledge of their ability to accumulate increased amounts of metals could be useful in the evaluation of environmental pollution in the alpine tundra of high mountains. Additionally, this investigation may contribute to understanding the rate and direction of recent vegetation change in Karkonosze and similar types of environments. Our investigation revealed that Carex rigida, C...
July 12, 2017: Environmental Science and Pollution Research International
Munusamy Madhaiyan, Selvaraj Poonguzhali, Venkatakrishnan Sivaraj Saravanan, Veeramuthu Duraipandiyan, Naif Abdullah Al-Dhabi, Soon-Wo Kwon, William B Whitman
A novel xylanolytic and cellulolytic strain, BL9T, was isolated from leaves of the Bamboo plants maintained at the Tamil Nadu Agricultural University Campus, Coimbatore, India. On the basis of the results of 16S rRNA gene analysis, it was determined to be phylogenetically close to the type strains of Paenibacillus amylolyticus NRRL NRS-290T (98.3 %), Paenibacillus barcinonensis BP-23T (98.1 %), Paenibacillus tundrae A10bT (98.0 %) and Paenibacillus xylanexedens B22aT (97.6 %). The strain stained Gram variable and was aerobic, motile and catalase- and oxidase-positive, with rod-shaped cells...
July 2017: International Journal of Systematic and Evolutionary Microbiology
Tara J Zamin, Steeve D Côté, Jean-Pierre Tremblay, Paul Grogan
Global declines in caribou and reindeer (Rangifer) populations have drawn attention to the myriad of stressors that these Arctic and boreal forest herbivores currently face. Arctic warming has resulted in increased tundra shrub growth and therefore Rangifer forage quantity. However, its effects on forage quality have not yet been addressed although they may be critical to Rangifer body condition and fecundity. We investigated the impact of 8 yrs of summer warming on the quality of forage available to the Bathurst caribou herd using experimental greenhouses (n = 5) located in mesic birch hummock tundra in the central Canadian Low Arctic...
October 2017: Ecological Applications: a Publication of the Ecological Society of America
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