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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...
January 9, 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...
December 22, 2017: Oecologia
Jacob Nabe-Nielsen, Signe Normand, Francis K C Hui, Lærke Stewart, Christian Bay, Louise I Nabe-Nielsen, Niels Martin Schmidt
Arctic plant communities are altered by climate changes. The magnitude of these alterations depends on whether species distributions are determined by macroclimatic conditions, by factors related to local topography, or by biotic interactions. Our current understanding of the relative importance of these conditions is limited due to the scarcity of studies, especially in the High Arctic. We investigated variations in vascular plant community composition and species richness based on 288 plots distributed on three sites along a coast-inland gradient in Northeast Greenland using a stratified random design...
December 2017: Ecology and Evolution
Daan Blok, Samuel Faucherre, Imre Banyasz, Riikka Rinnan, Anders Michelsen, Bo Elberling
Tundra regions are projected to warm rapidly during the coming decades. The tundra biome holds the largest terrestrial carbon pool, largely contained in frozen permafrost soils. With warming, these permafrost soils may thaw and become available for microbial decomposition, potentially providing a positive feedback to global warming. Warming may directly stimulate microbial metabolism but may also indirectly stimulate organic matter turnover through increased plant productivity by soil priming from root exudates and accelerated litter turnover rates...
December 13, 2017: Global Change Biology
Marius Hauglin, Ole Martin Bollandsås, Terje Gobakken, Erik Næsset
Monitoring of forest resources through national forest inventory programmes is carried out in many countries. The expected climate changes will affect trees and forests and might cause an expansion of trees into presently treeless areas, such as above the current alpine tree line. It is therefore a need to develop methods that enable the inclusion of also these areas into monitoring programmes. Airborne laser scanning (ALS) is an established tool in operational forest inventories, and could be a viable option for monitoring tasks...
December 8, 2017: Environmental Monitoring and Assessment
Jing Tang, Alla Y Yurova, Guy Schurgers, Paul A Miller, Stefan Olin, Benjamin Smith, Matthias B Siewert, David Olefeldt, Petter Pilesjö, Anneli Poska
Tundra soils account for 50% of global stocks of soil organic carbon (SOC), and it is expected that the amplified climate warming in high latitude could cause loss of this SOC through decomposition. Decomposed SOC could become hydrologically accessible, which increase downstream dissolved organic carbon (DOC) export and subsequent carbon release to the atmosphere, constituting a positive feedback to climate warming. However, DOC export is often neglected in ecosystem models. In this paper, we incorporate processes related to DOC production, mineralization, diffusion, sorption-desorption, and leaching into a customized arctic version of the dynamic ecosystem model LPJ-GUESS in order to mechanistically model catchment DOC export, and to link this flux to other ecosystem processes...
December 4, 2017: Science of the Total Environment
Decai Gao, Lei Zhang, Jun Liu, Bo Peng, Zhenzhen Fan, Weiwei Dai, Ping Jiang, Edith Bai
Altered freeze-thaw cycle (FTC) patterns due to global climate change may affect nitrogen (N) cycling in terrestrial ecosystems. However, the general responses of soil N pools and fluxes to different FTC patterns are still poorly understood. Here, we compiled data of 1519 observations from 63 studies and conducted a meta-analysis of the responses of 17 variables involved in terrestrial N pools and fluxes to FTC. Results showed that under FTC treatment, soil NH4+ , NO3- , NO3- leaching, and N2 O emission significantly increased by 18...
December 7, 2017: Global Change Biology
Siavash Atashgahi, Max M Häggblom, Hauke Smidt
Halogenated organic compounds, also termed organohalogens, were initially considered to be of almost exclusively anthropogenic origin. However, over 5000 naturally-synthesized organohalogens are known today. This has also fuelled the hypothesis that the natural and ancient origin of organohalogens could have primed development of metabolic machineries for their degradation, especially in microorganisms. Among these, a special group of anaerobic microorganisms was discovered that could conserve energy by reducing organohalogens as terminal electron acceptor in a process termed organohalide respiration...
December 7, 2017: Environmental Microbiology
Tage Vowles, Bengt Gunnarsson, Ulf Molau, Thomas Hickler, Leif Klemedtsson, Robert G Björk
One of the most palpable effects of warming in Arctic ecosystems is shrub expansion above the tree line. However, previous studies have found that reindeer can influence plant community responses to warming and inhibit shrubification of the tundra.We revisited grazed (ambient) and ungrazed study plots (exclosures), at the southern as well as the northern limits of the Swedish alpine region, to study long-term grazing effects and vegetation changes in response to increasing temperatures between 1995 and 2011, in two vegetation types (shrub heath and mountain birch forest)...
November 2017: Journal of Ecology
Dockyu Kim, Ha Ju Park, Woo Jun Sul, Hyun Park
Although humic acids (HA) are involved in many biological processes in soils and thus their ecological importance has received much attention, the degradative pathways and corresponding catalytic genes underlying the HA degradation by bacteria remain unclear. To unveil those uncertainties, we analyzed transcriptomes extracted from Pseudomonas sp. PAMC 26793 cells time-dependently induced in the presence of HA in a lab flask. Out of 6288 genes, 299 (microarray) and 585 (RNA-seq) were up-regulated by > 2...
December 1, 2017: Folia Microbiologica
Sandra Lai, Adrien Quiles, Josie Lambourdière, Dominique Berteaux, Aude Lalis
OBJECTIVE: The arctic fox (Vulpes lagopus) is a circumpolar species inhabiting all accessible Arctic tundra habitats. The species forms a panmictic population over areas connected by sea ice, but recently, kin clustering and population differentiation were detected even in regions where sea ice was present. The purpose of this study was to examine the genetic structure of a population in the High Arctic using a robust panel of highly polymorphic microsatellites. RESULTS: We analyzed the genotypes of 210 individuals from Bylot Island, Nunavut, Canada, using 15 microsatellite loci...
December 1, 2017: BMC Research Notes
Thomas C Parker, Jianwu Tang, Mahalia B Clark, Michael M Moody, Ned Fetcher
Eriophorum vaginatum is a tussock-forming sedge that contributes significantly to the structure and primary productivity of moist acidic tussock tundra. Locally adapted populations (ecotypes) have been identified across the geographical distribution of E. vaginatum; however, little is known about how their growth and phenology differ over the course of a growing season. The growing season is short in the Arctic and therefore exerts a strong selection pressure on tundra species. This raises the hypothesis that the phenology of arctic species may be poorly adapted if the timing and length of the growing season change...
November 2017: Ecology and Evolution
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