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Hongmei Chen, Ziming Yang, Rosalie K Chu, Nikola Toliċ, Liyuan Liang, David E Graham, Stan D Wullschleger, Baohua Gu
Molecular composition of the Arctic soil organic carbon (SOC) and its susceptibility to microbial degradation are uncertain due to heterogeneity and unknown SOC compositions. Using ultrahigh resolution mass spectrometry, we determined the susceptibility and compositional changes of extractable dissolved organic matter (EDOM) in an anoxic warming incubation experiment (up to 122 days) with a tundra soil from Alaska, United States. EDOM was extracted with 10 mM NH4HCO3 from both the organic and mineral-layer soils during incubation at either -2 or 8°C...
March 23, 2018: Environmental Science & Technology
Claire C Treat, A Anthony Bloom, Maija E Marushchak
Wetlands are the single largest natural source of atmospheric methane (CH4 ), a greenhouse gas, and occur extensively in the northern hemisphere. Large discrepancies remain between "bottom-up" and "top-down" estimates of northern CH4 emissions. To explore whether these discrepancies are due to poor representation of non-growing season CH4 emissions, we synthesized non-growing season and annual CH4 flux measurements from temperate, boreal, and tundra wetlands and uplands. Median non-growing season wetland emissions ranged from 0...
March 22, 2018: Global Change Biology
Mark A Lee
Forage plants are valuable because they maintain wild and domesticated herbivores, and sustain the delivery of meat, milk and other commodities. Forage plants contain different quantities of fibre, lignin, minerals and protein, and vary in the proportion of their tissue that can be digested by herbivores. These nutritive components are important determinants of consumer growth rates, reproductive success and behaviour. A dataset was compiled to quantify variation in forage plant nutritive values within- and between-plant species, and to assess variation between plant functional groups and bioclimatic zones...
March 17, 2018: Journal of Plant Research
Xue-Yan Liu, Keisuke Koba, Lina A Koyama, Sarah E Hobbie, Marissa S Weiss, Yoshiyuki Inagaki, Gaius R Shaver, Anne E Giblin, Satoru Hobara, Knute J Nadelhoffer, Martin Sommerkorn, Edward B Rastetter, George W Kling, James A Laundre, Yuriko Yano, Akiko Makabe, Midori Yano, Cong-Qiang Liu
Plant nitrogen (N) use is a key component of the N cycle in terrestrial ecosystems. The supply of N to plants affects community species composition and ecosystem processes such as photosynthesis and carbon (C) accumulation. However, the availabilities and relative importance of different N forms to plants are not well understood. While nitrate (NO3 - ) is a major N form used by plants worldwide, it is discounted as a N source for Arctic tundra plants because of extremely low NO3 - concentrations in Arctic tundra soils, undetectable soil nitrification, and plant-tissue NO3 - that is typically below detection limits...
March 14, 2018: Proceedings of the National Academy of Sciences of the United States of America
Maria Myrstener, Gerard Rocher-Ros, Ryan M Burrows, Ann-Kristin Bergström, Reiner Giesler, Ryan A Sponseller
Climate change is rapidly reshaping arctic landscapes through shifts in vegetation cover and productivity, soil resource mobilization, and hydrological regimes. The implications of these changes for stream ecosystems and food webs is unclear and will depend largely on microbial biofilm responses to concurrent shifts in temperature, light, and resource supply from land. To study those responses, we used nutrient diffusing substrates to manipulate resource supply to biofilm communities along regional gradients in stream temperature, riparian shading, and dissolved organic carbon (DOC) loading in arctic Sweden...
March 8, 2018: Global Change Biology
Tao Bao, Renbin Zhu, Pei Wang, Wenjuan Ye, Dawei Ma, Hua Xu
Stratospheric ozone has begun to recover in Antarctica since the implementation of the Montreal Protocol. However, the effects of ultraviolet (UV) radiation on tundra greenhouse gas fluxes are rarely reported for Polar Regions. In the present study, tundra N2 O and CH4 fluxes were measured under the simulated reduction of UV radiation in maritime Antarctica over the last three-year summers. Significantly enhanced N2 O and CH4 emissions occurred at tundra sites under the simulated reduction of UV radiation. Compared with the ambient normal UV level, a 20% reduction in UV radiation increased tundra emissions by an average of 8 μg N2 O m-2 h-1 and 93 μg CH4 m-2 h-1 , whereas a 50% reduction in UV radiation increased their emissions by an average of 17 μg N2 O m-2 h-1 and 128 μg CH4 m-2 h-1 ...
February 27, 2018: Scientific Reports
Neslihan Taş, Emmanuel Prestat, Shi Wang, Yuxin Wu, Craig Ulrich, Timothy Kneafsey, Susannah G Tringe, Margaret S Torn, Susan S Hubbard, Janet K Jansson
In the Arctic, environmental factors governing microbial degradation of soil carbon (C) in active layer and permafrost are poorly understood. Here we determined the functional potential of soil microbiomes horizontally and vertically across a cryoperturbed polygonal landscape in Alaska. With comparative metagenomics, genome binning of novel microbes, and gas flux measurements we show that microbial greenhouse gas (GHG) production is strongly correlated to landscape topography. Active layer and permafrost harbor contrasting microbiomes, with increasing amounts of Actinobacteria correlating with decreasing soil C in permafrost...
February 22, 2018: Nature Communications
Svetlana E Belova, Natalia E Suzina, W Irene C Rijpstra, Jaap S Sinninghe Damsté, Svetlana N Dedysh
An isolate of aerobic, Gram-stain-negative, rod-shaped, non-motile and light-pink pigmented bacteria, designated SBC68T , was obtained from slightly decomposed thalli of the lichen Cladonia sp. collected from the forested tundra of north-western Siberia. Cells of this isolate occurred singly, in pairs or in rosettes. These bacteria were acidophilic (optimum growth at pH 4.3-5.6) and mesophilic (optimum growth at 20-30 °C) but were also capable of growth at low temperatures, down to 7 °C. The preferred growth substrates were sugars, some organic acids and lichenan...
February 21, 2018: International Journal of Systematic and Evolutionary Microbiology
Christopher Carcaillet, Jean-Louis Latil, Sébastien Abou, Adam Ali, Bassam Ghaleb, Frédéric Magnin, Paul Roiron, Serge Aubert
Up to now, the most widely accepted idea of the periglacial environment is that of treeless ecosystems such as the arctic or the alpine tundra, also called the tabula rasa paradigm. However, several palaeoecological studies have recently challenged this idea, that is, treeless environments in periglacial areas where all organisms would have been exterminated near the glacier formed during the Last Glacial Maximum, notably in the Scandinavian mountains. In the Alps, the issue of glacial refugia of trees remains unanswered...
February 21, 2018: Global Change Biology
Bronisław Wojtuń, Aleksandra Samecka-Cymerman, Krzysztof Kolon, Alexander J Kempers
Arctic-alpine tundra habitats are very vulnerable to the input of relatively small amounts of xenobiotics, and thus their level in such areas must be carefully controlled. Therefore, we collected the terrestrial widespread moss Racomitrium lanuginosum (Hedw.) Brid. in Spitsbergen in the Arctic moss lichen tundra and, for comparison, in the Arctic-alpine tundra in the Karkonosze (SW Poland). Concentrations of the elements Cd, Co, Cr, Cu, Fe, Hg, Li, Mn, Mo, Na, Ni, Pb, V, and Zn in this species and in the parent rock material were measured...
February 19, 2018: Environmental Science and Pollution Research International
C T Christiansen, M J Lafreniére, G H R Henry, P Grogan
Arctic climate warming will be primarily during winter, resulting in increased snowfall in many regions. Previous tundra research on the impacts of deepened snow has generally been of short duration. Here, we report relatively long-term (7-9 years) effects of experimentally deepened snow on plant community structure, net ecosystem CO2 exchange (NEE), and soil biogeochemistry in Canadian Low Arctic mesic shrub tundra.The snowfence treatment enhanced snow depth from 0.3 to ~1 m, increasing winter soil temperatures by ~3°C, but with no effect on summer soil temperature, moisture, or thaw depth...
February 7, 2018: Global Change Biology
Mark J Lara, Ingmar Nitze, Guido Grosse, Philip Martin, A David McGuire
Arctic tundra ecosystems have experienced unprecedented change associated with climate warming over recent decades. Across the Pan-Arctic, vegetation productivity and surface greenness have trended positively over the period of satellite observation. However, since 2011 these trends have slowed considerably, showing signs of browning in many regions. It is unclear what factors are driving this change and which regions/landforms will be most sensitive to future browning. Here we provide evidence linking decadal patterns in arctic greening and browning with regional climate change and local permafrost-driven landscape heterogeneity...
February 5, 2018: Scientific Reports
Fan Jiang, Wangmu Danzeng, Yuming Zhang, Yan Zhang, Li Jiang, Jia Liu, Lu Lu, Wei Fan, Fang Peng
A red-pigmented, Gram-reaction-negative, aerobic, non-motile and rod-shaped bacterium, designated NY03-3-30T, was isolated from a soil sample collected from Inexpressible Island, Northern Victoria Land of the Antarctic Ross Orogen, and subjected to a polyphasic taxonomic study. Growth occurred at 4-28 °C (optimum 20 °C) and at pH 6.0-9.0 (optimum pH 7.0). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain NY03-3-30T belonged to the genus Hymenobacter in the family Cytophagaceae...
February 2018: International Journal of Systematic and Evolutionary Microbiology
Binish Mechirackal Balan, Sruthy Shini, Kottekkattu P Krishnan, Mahesh Mohan
Mercury tolerant bacteria Pseudarthrobacter oxydans strain MM20 and Pseudomonas frederiksbergensis strain SS18 were isolated from the tundra ecosystem of Ny-Ålesund, Svalbard, where commercial exploitation of the coal existed till 1960s. Minimum inhibitory concentration (MIC), mercury removal, mercury biosorption, and antibiotic resistance of these strains were analyzed. P. frederiksbergensis strain SS18 showed high tolerance (2.0 ppm) to mercury than P. oxydans strain MM20 (1.5 ppm). Mercury removal and biosorption studies were carried out in liquid media containing 1...
January 31, 2018: Journal of Basic Microbiology
Tage Vowles, Frida Lindwall, Alf Ekblad, Mohammad Bahram, Brendan R Furneaux, Martin Ryberg, Robert G Björk
Mycorrhizal associations are widespread in high-latitude ecosystems and are potentially of great importance for global carbon dynamics. Although large herbivores play a key part in shaping subarctic plant communities, their impact on mycorrhizal dynamics is largely unknown. We measured extramatrical mycelial (EMM) biomass during one growing season in 16-year-old herbivore exclosures and unenclosed control plots (ambient), at three mountain birch forests and two shrub heath sites, in the Scandes forest-tundra ecotone...
January 2018: Ecology and Evolution
Javier Sánchez Romano, Torill Mørk, Sauli Laaksonen, Erik Ågren, Ingebjørg H Nymo, Marianne Sunde, Morten Tryland
BACKGROUND: Infectious keratoconjunctivitis (IKC) is one of the most common ocular diseases in ruminants worldwide. In addition to keratitis and conjunctivitis, animals with IKC can develop uveitis, corneal ulcer, and in severe cases, blindness. The bacteria Moraxella spp. has been described as the primary causative agent of infectious bovine keratoconjunctivitis (IBK) in cattle (Bos taurus), while Chlamydia spp. and Mycoplasma conjunctivae are considered the main causative agents of IKC in sheep (Ovis aries)...
January 16, 2018: BMC Veterinary Research
Michael E Donaldson, Yessica Rico, Karsten Hueffer, Halie M Rando, Anna V Kukekova, Christopher J Kyle
Pathogens are recognized as major drivers of local adaptation in wildlife systems. By determining which gene variants are favored in local interactions among populations with and without disease, spatially explicit adaptive responses to pathogens can be elucidated. Much of our current understanding of host responses to disease comes from a small number of genes associated with an immune response. High-throughput sequencing (HTS) technologies, such as genotype-by-sequencing (GBS), facilitate expanded explorations of genomic variation among populations...
January 2018: Ecology and Evolution
Douglas J McCauley, Gabriel Gellner, Neo D Martinez, Richard J Williams, Stuart A Sandin, Fiorenza Micheli, Peter J Mumby, Kevin S McCann
Classically, biomass partitioning across trophic levels was thought to add up to a pyramidal distribution. Numerous exceptions have, however, been noted including complete pyramidal inversions. Elevated levels of biomass top-heaviness (i.e. high consumer/resource biomass ratios) have been reported from Arctic tundra communities to Brazilian phytotelmata, and in species assemblages as diverse as those dominated by sharks and ants. We highlight two major pathways for creating top-heaviness, via: (1) endogenous channels that enhance energy transfer across trophic boundaries within a community and (2) exogenous pathways that transfer energy into communities from across spatial and temporal boundaries...
March 2018: Ecology Letters
Sabrina Träger, Ann Milbau, Scott D Wilson
Plant contributions to the nitrogen (N) cycle from decomposition are likely to be altered by vegetation shifts associated with climate change. Roots account for the majority of soil organic matter input from vegetation, but little is known about differences between vegetation types in their root contributions to nutrient cycling. Here, we examine the potential contribution of fine roots to the N cycle in forest and tundra to gain insight into belowground consequences of the widely observed increase in woody vegetation that accompanies climate change in the Arctic...
December 2017: Ecology and Evolution
Shota Masumoto, Masaki Uchida, Motoaki Tojo, Maria Luz Herrero, Akira S Mori, Satoshi Imura
In Arctic tundra, plant pathogens have substantial effects on the growth and survival of hosts, and impacts on the carbon balance at the scale of ecological systems. To understand these effects on carbon dynamics across different scales including plant organ, individual, population and ecosystem, we focused on two primary factors: host productivity reduction and carbon consumption by the pathogen. We measured the effect of the pathogen on photosynthetic and respiratory activity in the host. We also measured respiration and the amount of carbon in the pathogen...
March 2018: Oecologia
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