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https://www.readbyqxmd.com/read/28208232/non-linear-co2-flux-response-to-seven-years-of-experimentally-induced-permafrost-thaw
#1
Marguerite Mauritz, Rosvel Bracho, Gerardo Celis, Jack Hutchings, Susan M Natali, Elaine Pegoraro, Verity G Salmon, Christina Schädel, Elizabeth E Webb, Edward A G Schuur
Rapid Arctic warming is expected to increase global greenhouse gas concentrations as permafrost thaw exposes immense stores of frozen carbon (C) to microbial decomposition. Permafrost thaw also stimulates plant growth, which could offset C loss. Using data from seven years of experimental Air and Soil warming in moist acidic tundra, we show that Soil warming had a much stronger effect on CO2 flux than Air warming. Soil warming caused rapid permafrost thaw and increased ecosystem respiration (Reco), gross primary productivity (GPP), and net summer CO2 storage (NEE)...
February 16, 2017: Global Change Biology
https://www.readbyqxmd.com/read/28194307/vascular-plant-biodiversity-of-the-lower-coppermine-river-valley-and-vicinity-nunavut-canada-an-annotated-checklist-of-an-arctic-flora
#2
Jeffery M Saarela, Paul C Sokoloff, Roger D Bull
The Coppermine River in western Nunavut is one of Canada's great Arctic rivers, yet its vascular plant flora is poorly known. Here, we report the results of a floristic inventory of the lower Coppermine River valley and vicinity, including Kugluk (Bloody Falls) Territorial Park and the hamlet of Kugluktuk. The study area is approximately 1,200 km(2), extending from the forest-tundra south of the treeline to the Arctic coast. Vascular plant floristic data are based on a review of all previous collections from the area and more than 1,200 new collections made in 2014...
2017: PeerJ
https://www.readbyqxmd.com/read/28135298/explicit-not-implicit-preferences-predict-conservation-intentions-for-endangered-species-and-biomes
#3
Alejandra Echeverri, Megan M Callahan, Kai M A Chan, Terre Satterfield, Jiaying Zhao
Conservation of biodiversity is determined in part by human preferences. Preferences relevant to conservation have been examined largely via explicit measures (e.g., a self-reported degree of liking), with implicit measures (e.g., preconscious, automatic evaluations) receiving relatively less attention. This is the case despite psychological evidence from other contexts that implicit preferences are more informative of behavior. Thus, the type of measure that predicts conservation intentions for biodiversity is unknown...
2017: PloS One
https://www.readbyqxmd.com/read/28117440/elevation-alters-ecosystem-properties-across-temperate-treelines-globally
#4
Jordan R Mayor, Nathan J Sanders, Aimée T Classen, Richard D Bardgett, Jean-Christophe Clément, Alex Fajardo, Sandra Lavorel, Maja K Sundqvist, Michael Bahn, Chelsea Chisholm, Ellen Cieraad, Ze'ev Gedalof, Karl Grigulis, Gaku Kudo, Daniel L Oberski, David A Wardle
Temperature is a primary driver of the distribution of biodiversity as well as of ecosystem boundaries. Declining temperature with increasing elevation in montane systems has long been recognized as a major factor shaping plant community biodiversity, metabolic processes, and ecosystem dynamics. Elevational gradients, as thermoclines, also enable prediction of long-term ecological responses to climate warming. One of the most striking manifestations of increasing elevation is the abrupt transitions from forest to treeless alpine tundra...
January 25, 2017: Nature
https://www.readbyqxmd.com/read/28116692/toward-a-statistical-description-of-methane-emissions-from-arctic-wetlands
#5
Norbert Pirk, Mikhail Mastepanov, Efrén López-Blanco, Louise H Christensen, Hanne H Christiansen, Birger Ulf Hansen, Magnus Lund, Frans-Jan W Parmentier, Kirstine Skov, Torben R Christensen
Methane (CH4) emissions from arctic tundra typically follow relations with soil temperature and water table depth, but these process-based descriptions can be difficult to apply to areas where no measurements exist. We formulated a description of the broader temporal flux pattern in the growing season based on two distinct CH4 source components from slow and fast-turnover carbon. We used automatic closed chamber flux measurements from NE Greenland (74°N), W Greenland (64°N), and Svalbard (78°N) to identify and discuss these components...
February 2017: Ambio
https://www.readbyqxmd.com/read/28116688/spatiotemporal-variability-in-surface-energy-balance-across-tundra-snow-and-ice-in-greenland
#6
Magnus Lund, Christian Stiegler, Jakob Abermann, Michele Citterio, Birger U Hansen, Dirk van As
The surface energy balance (SEB) is essential for understanding the coupled cryosphere-atmosphere system in the Arctic. In this study, we investigate the spatiotemporal variability in SEB across tundra, snow and ice. During the snow-free period, the main energy sink for ice sites is surface melt. For tundra, energy is used for sensible and latent heat flux and soil heat flux leading to permafrost thaw. Longer snow-free period increases melting of the Greenland Ice Sheet and glaciers and may promote tundra permafrost thaw...
February 2017: Ambio
https://www.readbyqxmd.com/read/28116687/larval-outbreaks-in-west-greenland-instant-and-subsequent-effects-on-tundra-ecosystem-productivity-and-co2-exchange
#7
Magnus Lund, Katrine Raundrup, Andreas Westergaard-Nielsen, Efrén López-Blanco, Josephine Nymand, Peter Aastrup
Insect outbreaks can have important consequences for tundra ecosystems. In this study, we synthesise available information on outbreaks of larvae of the noctuid moth Eurois occulta in Greenland. Based on an extensive dataset from a monitoring programme in Kobbefjord, West Greenland, we demonstrate effects of a larval outbreak in 2011 on vegetation productivity and CO2 exchange. We estimate a decreased carbon (C) sink strength in the order of 118-143 g C m(-2), corresponding to 1210-1470 tonnes C at the Kobbefjord catchment scale...
February 2017: Ambio
https://www.readbyqxmd.com/read/28107770/different-parts-different-stories-climate-sensitivity-of-growth-is-stronger-in-root-collars-versus-stems-in-tundra-shrubs
#8
Pascale Ropars, Sandra Angers-Blondin, Marianne Gagnon, Isla H Myers-Smith, Esther Lévesque, Stéphane Boudreau
Shrub densification has been widely reported across the circumpolar arctic and subarctic biomes in recent years. Long-term analyses based on dendrochronological techniques applied to shrubs have linked this phenomenon to climate change. However, the multi-stemmed structure of shrubs makes them difficult to sample and therefore leads to non-uniform sampling protocols among shrub ecologists, who will favor either root collars or stems to conduct dendrochronological analyses. Through a comparative study of the use of root collars and stems of Betula glandulosa, a common North American shrub species, we evaluated the relative sensitivity of each plant part to climate variables, and assessed if this sensitivity is consistent across three different types of environments in northwestern Québec, Canada (terrace, hilltop and snowbed)...
January 20, 2017: Global Change Biology
https://www.readbyqxmd.com/read/28079308/greater-temperature-sensitivity-of-plant-phenology-at-colder-sites-implications-for-convergence-across-northern-latitudes
#9
Janet Prevéy, Mark Vellend, Nadja Rüger, Robert D Hollister, Anne D Bjorkman, Isla H Myers-Smith, Sarah C Elmendorf, Karin Clark, Elisabeth J Cooper, Bo Elberling, Anna Maria Fosaa, Gregory H R Henry, Toke T Høye, Ingibjörg Svala Jónsdóttir, Kari Klanderud, Esther Lévesque, Marguerite Mauritz, Ulf Molau, Susan M Natali, Steven F Oberbauer, Zoe A Panchen, Eric Post, Sabine B Rumpf, Niels M Schmidt, Ted Schuur, Phillip R Semenchuk, Tiffany Troxler, Jeffrey M Welker, Christian Rixen
Warmer temperatures are accelerating the phenology of organisms around the world. Temperature sensitivity of phenology might be greater in colder, higher-latitude sites than in warmer regions, in part because small changes in temperature constitute greater relative changes in thermal balance at colder sites. To test this hypothesis, we examined up to 20 years of phenology data for 47 tundra plant species at 18 high-latitude sites along a climatic gradient. Across all species, the timing of leaf emergence and flowering were more sensitive to a given increase in summer temperature at colder than warmer high-latitude locations...
January 11, 2017: Global Change Biology
https://www.readbyqxmd.com/read/28063181/climatic-warming-strengthens-a-positive-feedback-between-alpine-shrubs-and-fire
#10
James S Camac, Richard J Williams, Carl-Henrik Wahren, Ary A Hoffmann, Peter A Vesk
Climate change is expected to increase fire activity and woody plant encroachment in arctic and alpine landscapes. However, the extent to which these increases interact to affect the structure, function and composition of alpine ecosystems is largely unknown. Here we use field surveys and experimental manipulations to examine how warming and fire affect recruitment, seedling growth and seedling survival in four dominant Australian alpine shrubs. We found that fire increased establishment of shrub seedlings by as much as 33-fold...
January 7, 2017: Global Change Biology
https://www.readbyqxmd.com/read/28062107/diurnal-evolution-of-the-temperature-sensitivity-of-co2-efflux-in-permafrost-soils-under-control-and-warm-conditions
#11
Julien Fouché, Catherine Keller, Michel Allard, Jean Paul Ambrosi
Cryosols contain ~33% of the global soil organic carbon. Cryosol warming and permafrost degradation may enhance the CO2 release to the atmosphere through the microbial decomposition. Despite the large carbon pool, the permafrost carbon feedback on the climate remains uncertain. In this study, we aimed at better understanding the diurnal evolution of the temperature sensitivity of CO2 efflux in Cryosols. A Histic Cryosol and a Turbic Cryosol were instrumented in tussock tundra ecosystems near Salluit (Nunavik, Canada)...
January 3, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28028549/ssunique-detecting-sequence-novelty-in-microbiome-surveys
#12
Michael D J Lynch, Josh D Neufeld
High-throughput sequencing of small-subunit (SSU) rRNA genes has revolutionized understanding of microbial communities and facilitated investigations into ecological dynamics at unprecedented scales. Such extensive SSU rRNA gene sequence libraries, constructed from DNA extracts of environmental or host-associated samples, often contain a substantial proportion of unclassified sequences, many representing organisms with novel taxonomy (taxonomic "blind spots") and potentially unique ecology. Indeed, these novel taxonomic lineages are associated with so-called microbial "dark matter," which is the genomic potential of these lineages...
November 2016: MSystems
https://www.readbyqxmd.com/read/27994976/diversity-taxonomic-composition-and-functional-aspects-of-fungal-communities-in-living-senesced-and-fallen-leaves-at-five-sites-across-north-america
#13
Jana M U'Ren, A Elizabeth Arnold
BACKGROUND: Fungal endophytes inhabit symptomless, living tissues of all major plant lineages to form one of earth's most prevalent groups of symbionts. Many reproduce from senesced and/or decomposing leaves and can produce extracellular leaf-degrading enzymes, blurring the line between symbiotrophy and saprotrophy. To better understand the endophyte-saprotroph continuum we compared fungal communities and functional traits of focal strains isolated from living leaves to those isolated from leaves after senescence and decomposition, with a focus on foliage of woody plants in five biogeographic provinces ranging from tundra to subtropical scrub forest...
2016: PeerJ
https://www.readbyqxmd.com/read/27974492/highly-individualistic-rates-of-plant-phenological-advance-associated-with-arctic-sea-ice-dynamics
#14
Eric Post, Jeffrey Kerby, Christian Pedersen, Heidi Steltzer
We analysed 12 years of species-specific emergence dates of plants at a Low-Arctic site near Kangerlussuaq, Greenland to investigate associations with sea ice dynamics, a potential contributor to local temperature variation in near-coastal tundra. Species displayed highly variable rates of phenological advance, from a maximum of -2.55 ± 0.17 and -2.93 ± 0.51 d yr(-1) among a graminoid and forb, respectively, to a minimum of -0.55 ± 0.19 d yr(-1) or no advance at all in the two deciduous shrub species. Monthly Arctic-wide sea ice extent was a significant predictor of emergence timing in 10 of 14 species...
December 2016: Biology Letters
https://www.readbyqxmd.com/read/27933047/diazotroph-diversity-in-the-sea-ice-melt-ponds-and-surface-waters-of-the-eurasian-basin-of-the-central-arctic-ocean
#15
Mar Fernández-Méndez, Kendra A Turk-Kubo, Pier L Buttigieg, Josephine Z Rapp, Thomas Krumpen, Jonathan P Zehr, Antje Boetius
The Eurasian basin of the Central Arctic Ocean is nitrogen limited, but little is known about the presence and role of nitrogen-fixing bacteria. Recent studies have indicated the occurrence of diazotrophs in Arctic coastal waters potentially of riverine origin. Here, we investigated the presence of diazotrophs in ice and surface waters of the Central Arctic Ocean in the summer of 2012. We identified diverse communities of putative diazotrophs through targeted analysis of the nifH gene, which encodes the iron protein of the nitrogenase enzyme...
2016: Frontiers in Microbiology
https://www.readbyqxmd.com/read/27928986/roseomonas-arcticisoli-sp-nov-isolated-from-arctic-tundra-soil
#16
Myong Chol Kim, Songguk Rim, Sehong Pak, Lvzhi Ren, Yumin Zhang, Xulu Chang, Xuhuan Li, Chengxiang Fang, Congyi Zheng, Fang Peng
No abstract text is available yet for this article.
November 2016: International Journal of Systematic and Evolutionary Microbiology
https://www.readbyqxmd.com/read/27917060/antarctotrechus-balli-sp-n-carabidae-trechini-the-first-ground-beetle-from-antarctica
#17
Allan C Ashworth, Terry L Erwin
Fossil elytra of a small trechine carabid are reported from the Oliver Bluffs on the Beardmore Glacier at lat. 85°S. They were compared with counterparts from the extant genera Trechisibus, Tasmanorites, Oxytrechus and Pseudocnides. The fossils share some characters but are sufficiently different to be described as a new genus and species. We named the new species Antarctotrechus balli in honour of George E. Ball who made major contributions to the study of carabids through his own research and the training of students while at the University of Alberta, Edmonton, Alberta, Canada...
2016: ZooKeys
https://www.readbyqxmd.com/read/27904966/treeline-advances-and-associated-shifts-in-the-ground-vegetation-alter-fine-root-dynamics-and-mycelia-production-in-the-south-and-polar-urals
#18
Emily F Solly, Ika Djukic, Pavel A Moiseev, Nelly I Andreyashkina, Nadezhda M Devi, Hans Göransson, Valeriy S Mazepa, Stepan G Shiyatov, Marina R Trubina, Fritz H Schweingruber, Martin Wilmking, Frank Hagedorn
Climate warming is shifting the elevational boundary between forests and tundra upwards, but the related belowground responses are poorly understood. In the pristine South and Polar Urals with shifts of the treeline ecotone documented by historical photographs, we investigated fine root dynamics and production of extramatrical mycorrhizal mycelia (EMM) along four elevational transects reaching from the closed forest to the treeless tundra. In addition, we analysed elevational differences in climate and vegetation structure, and excavated trees to estimate related changes in the partitioning between below- and aboveground biomass...
November 30, 2016: Oecologia
https://www.readbyqxmd.com/read/27902716/large-scale-anthropogenic-reduction-of-forest-cover-in-last-glacial-maximum-europe
#19
Jed O Kaplan, Mirjam Pfeiffer, Jan C A Kolen, Basil A S Davis
Reconstructions of the vegetation of Europe during the Last Glacial Maximum (LGM) are an enigma. Pollen-based analyses have suggested that Europe was largely covered by steppe and tundra, and forests persisted only in small refugia. Climate-vegetation model simulations on the other hand have consistently suggested that broad areas of Europe would have been suitable for forest, even in the depths of the last glaciation. Here we reconcile models with data by demonstrating that the highly mobile groups of hunter-gatherers that inhabited Europe at the LGM could have substantially reduced forest cover through the ignition of wildfires...
2016: PloS One
https://www.readbyqxmd.com/read/27898193/modeling-long-term-changes-in-tundra-carbon-balance-following-wildfire-climate-change-and-potential-nutrient-addition
#20
Yueyang Jiang, Edward B Rastetter, Gaius R Shaver, Adrian V Rocha, Qianlai Zhuang, Bonnie L Kwiatkowski
To investigate the underlying mechanisms that control long-term recovery of tundra carbon (C) and nutrients after fire, we employed the Multiple Element Limitation (MEL) model to simulate 200-yr post-fire changes in the biogeochemistry of three sites along a burn severity gradient in response to increases in air temperature, CO2 concentration, nitrogen (N) deposition, and phosphorus (P) weathering rates. The simulations were conducted for severely burned, moderately burned, and unburned arctic tundra. Our simulations indicated that recovery of C balance after fire was mainly determined by the internal redistribution of nutrients among ecosystem components (controlled by air temperature), rather than the supply of nutrients from external sources (e...
August 4, 2016: Ecological Applications: a Publication of the Ecological Society of America
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