Composition of soil assemblages across ecological drivers parallels that of nodule assemblages in ssp. in interior Alaska.

In root nodule symbioses (RNS) between nitrogen (N)-fixing bacteria and plants, bacterial symbionts cycle between nodule-inhabiting and soil-inhabiting niches that exert differential selection pressures on bacterial traits. Little is known about how the resulting evolutionary tension between host plants and symbiotic bacteria structures naturally occurring bacterial assemblages in soils. We used DNA cloning to examine soil-dwelling assemblages of the actinorhizal symbiont in sites with long-term stable assemblages in ssp.

State of Charge-Dependent Impedance Spectroscopy as a Helpful Tool to Identify Reasons for Fast Capacity Fading in All-Solid-State Batteries.

Thiophosphate-based all-solid-state batteries (ASSBs) are considered the most promising candidate for the next generation of energy storage systems. However, thiophosphate-based ASSBs suffer from fast capacity fading with nickel-rich cathode materials. In many reports, this capacity fading is attributed to an increase of the charge transfer resistance of the composite cathode caused by interface degradation and/or chemo-mechanical failure.

Evaluation and Improvement of the Stability of Poly(ethylene oxide)-based Solid-state Batteries with High-Voltage Cathodes.

Solid-state batteries (SSBs) with high-voltage cathode active materials (CAMs) such as LiNi Co Mn O (NCM) and poly(ethylene oxide) (PEO) suffer from "noisy voltage" related cell failure. Moreover, reports on their long-term cycling performance with high-voltage CAMs are not consistent. In this work, we verified that the penetration of lithium dendrites through the solid polymer electrolyte (SPE) indeed causes such "noisy voltage cell failure".

Impact of the Chlorination of Lithium Argyrodites on the Electrolyte/Cathode Interface in Solid-State Batteries.

Lithium argyrodite-type electrolytes are regarded as promising electrolytes due to their high ionic conductivity and good processability. Chemical modifications to increase ionic conductivity have already been demonstrated, but the influence of these modifications on interfacial stability remains so far unknown. In this work, we study Li PS Cl and Li PS Cl to investigate the influence of halogenation on the electrochemical decomposition of the solid electrolyte and the chemical degradation mechanism at the cathode interface in depth.

N and P constrain C in ecosystems under climate change: Role of nutrient redistribution, accumulation, and stoichiometry.

We use the Multiple Element Limitation (MEL) model to examine responses of 12 ecosystems to elevated carbon dioxide (CO ), warming, and 20% decreases or increases in precipitation. Ecosystems respond synergistically to elevated CO , warming, and decreased precipitation combined because higher water-use efficiency with elevated CO and higher fertility with warming compensate for responses to drought. Response to elevated CO , warming, and increased precipitation combined is additive.

A mechanistic investigation of the LiGePS|LiNiCoMnO interface stability in all-solid-state lithium batteries.

All-solid-state batteries are intensively investigated, although their performance is not yet satisfactory for large-scale applications. In this context, the combination of LiGePS solid electrolyte and LiNiCoMnO positive electrode active materials is considered promising despite the yet unsatisfactory battery performance induced by the thermodynamically unstable electrode|electrolyte interface. Here, we report electrochemical and spectrometric studies to monitor the interface evolution during cycling and understand the reactivity and degradation kinetics.

Correction: Widespread mortality of trembling aspen (Populus tremuloides) throughout interior Alaskan boreal forests resulting from a novel canker disease.

[This corrects the article DOI: 10.1371/journal.pone.

Influence of Mg-doping on the characteristics of ZnO photoanodes in dye-sensitized solar cells.

Dye-sensitized solar cells (DSSCs) based on ZnO photoanodes have, despite extensive research, lagged behind cells based on TiO, which is due to generally lower open-circuit voltages V and fill factors. Here, DSSCs have been prepared using Mg-doped ZnO (MZO) photoanodes based on nanoparticles, thin films or ZnO-MZO core-shell-type nanoparticles with varying Mg-concentration. The cells were studied in detailed photoelectrochemical and photoluminescence experiments.

Widespread mortality of trembling aspen (Populus tremuloides) throughout interior Alaskan boreal forests resulting from a novel canker disease.

Over the past several decades, growth declines and mortality of trembling aspen throughout western Canada and the United States have been linked to drought, often interacting with outbreaks of insects and fungal pathogens, resulting in a "sudden aspen decline" throughout much of aspen's range. In 2015, we noticed an aggressive fungal canker causing widespread mortality of aspen throughout interior Alaska and initiated a study to quantify potential drivers for the incidence, virulence, and distribution of the disease. Stand-level infection rates among 88 study sites distributed across 6 Alaska ecoregions ranged from <1 to 69%, with the proportion of trees with canker that were dead averaging 70% across all sites.

Can Siberian alder N-fixation offset N-loss after severe fire? Quantifying post-fire Siberian alder distribution, growth, and N-fixation in boreal Alaska.

Fire severity affects both ecosystem N-loss and post-fire N-balance. Climate change is altering the fire regime of interior Alaska, although the effects on Siberian alder (Alnus viridis ssp. fruticosa) annual N-fixation input (kg N ha-1 yr-1) and ecosystem N-balance are largely unknown.

Diverging surface reactions at TiO- or ZnO-based photoanodes in dye-sensitized solar cells.

Fast recombination of electrons from semiconductors with the oxidized redox species in the electrolyte represents a major bottleneck in the improvement of ZnO-based dye-sensitized solar cells (DSSCs). While processes at the semiconductor-electrolyte interface are well studied on TiO electrodes, the interactions of the ZnO surface with the electrolyte solution in DSSCs are less explored. This work aims at clarifying the different impact of the two contrasting redox couples I/I or [Co(bpy-pz)] (bpy-pz = bis(6-(1H-pyrazol-1-yl)-2,2'-bipyridine)) in electrolytes containing either no additives or Li ions and/or 4-tert-butlypyridine (TBP) in DSSCs using screen-printed nanoparticulate TiO (NP-TiO) or electrodeposited ZnO (ED-ZnO) photoanodes sensitized with the indoline dye DN216.

Stand basal area and solar radiation amplify white spruce climate sensitivity in interior Alaska: Evidence from carbon isotopes and tree rings.

The negative growth response of North American boreal forest trees to warm summers is well documented and the constraint of competition on tree growth widely reported, but the potential interaction between climate and competition in the boreal forest is not well studied. Because competition may amplify or mute tree climate-growth responses, understanding the role current forest structure plays in tree growth responses to climate is critical in assessing and managing future forest productivity in a warming climate. Using white spruce tree ring and carbon isotope data from a long-term vegetation monitoring program in Denali National Park and Preserve, we investigated the hypotheses that (a) competition and site moisture characteristics mediate white spruce radial growth response to climate and (b) moisture limitation is the mechanism for reduced growth.

Fire severity effects on soil carbon and nutrients and microbial processes in a Siberian larch forest.

Fire frequency and severity are increasing in tundra and boreal regions as climate warms, which can directly affect climate feedbacks by increasing carbon (C) emissions from combustion of the large soil C pool and indirectly via changes in vegetation, permafrost thaw, hydrology, and nutrient availability. To better understand the direct and indirect effects of changing fire regimes in northern ecosystems, we examined how differences in soil burn severity (i.e.

Functional responses of white spruce to snowshoe hare herbivory at the treeline.

Herbivores can modify the rate of shrub and treeline advance. Both direct and indirect effects of herbivory may simultaneously interact to affect the growth rates of plants at this ecotone. We investigated the effect of snowshoe hare herbivory on the height of white spruce at two treeline locations in Alaska, USA.

Can snowshoe hares control treeline expansions?

Treelines in Alaska are advancing in elevation and latitude because of climate warming, which is expanding the habitat available for boreal wildlife species, including snowshoe hares (Lepus americanus). Snowshoe hares are already present in tall shrub communities beyond treeline and are the main browser of white spruce (Picea glauca), the dominant tree species at treeline in Alaska. We investigated the processes involved in a "snowshoe hare filter" to white spruce establishment near treeline in Denali National Park, Alaska, USA.

Correction: Range Expansion of Moose in Arctic Alaska Linked to Warming and Increased Shrub Habitat.

[This corrects the article DOI: 10.1371/journal.pone.

Range Expansion of Moose in Arctic Alaska Linked to Warming and Increased Shrub Habitat.

Twentieth century warming has increased vegetation productivity and shrub cover across northern tundra and treeline regions, but effects on terrestrial wildlife have not been demonstrated on a comparable scale. During this period, Alaskan moose (Alces alces gigas) extended their range from the boreal forest into tundra riparian shrub habitat; similar extensions have been observed in Canada (A. a.

Stabilization of Organic-Inorganic Perovskite Layers by Partial Substitution of Iodide by Bromide in Methylammonium Lead Iodide.

Thin films of the methylammonium lead halides CH3 NH3 Pb(I1-x Brx )3 are prepared on fluorine-doped tin oxide substrates and exposed to humid air in the dark and under illumination. To characterize the stability of the materials, UV/Vis spectra are acquired at fixed intervals, accompanied by XRD, energy-dispersive X-ray spectroscopy, SEM, and confocal laser scanning microscopy. Different degradation mechanisms are observed depending on the environmental conditions.

Experimental evidence that ptarmigan regulate willow bud production to their own advantage.

In some ecosystems, vertebrate herbivores increase the nutritional quality and biomass of their food source through repeated grazing, thereby manipulating their environment to support higher densities of animals. We tested whether ptarmigan (Lagopus lagopus and L. muta) are capable of regulating the nutritional quality, abundance, and availability of feltleaf willow (Salix alaxensis) buds using a simulated browsing experiment and a feeding preference study with wild birds.

Herbivores influence the growth, reproduction, and morphology of a widespread Arctic willow.

Shrubs have expanded in Arctic ecosystems over the past century, resulting in significant changes to albedo, ecosystem function, and plant community composition. Willow and rock ptarmigan (Lagopus lagopus, L. muta) and moose (Alces alces) extensively browse Arctic shrubs, and may influence their architecture, growth, and reproduction.

Phylogeny and assemblage composition of Frankia in Alnus tenuifolia nodules across a primary successional sere in interior Alaska.

In nitrogen (N) fixing symbioses, host-symbiont specificity, genetic variation in bacterial symbionts and environmental variation represent fundamental constraints on the ecology, evolution and practical uses of these interactions, but detailed information is lacking for many naturally occurring N-fixers. This study examined phylogenetic host specificity of Frankia in field-collected nodules of two Alnus species (A. tenuifolia and A.

CO2 efflux from cleared mangrove peat.

Background: CO(2) emissions from cleared mangrove areas may be substantial, increasing the costs of continued losses of these ecosystems, particularly in mangroves that have highly organic soils.

Methodology/principal Findings: We measured CO(2) efflux from mangrove soils that had been cleared for up to 20 years on the islands of Twin Cays, Belize. We also disturbed these cleared peat soils to assess what disturbance of soils after clearing may have on CO(2) efflux.

Psychrotrophic strain of Janthinobacterium lividum from a cold Alaskan soil produces prodigiosin.

We have explored the microbial community in a nonpermafrost, cold Alaskan soil using both culture-based and culture-independent approaches. In the present study, we cultured >1000 bacterial isolates from this soil and characterized the collection of isolates phylogenetically and functionally. A screen for antibiosis identified an atypical, red-pigmented strain of Janthinobacterium lividum (strain BR01) that produced prodigiosin when grown at cool temperatures as well as strains (e.

Variation in carbohydrate source-sink relations of forest and treeline white spruce in southern, interior and northern Alaska.

Two opposing hypotheses have been presented to explain reduced tree growth at the treeline, compared with growth in lower elevation or lower latitude forests: the carbon source and sink limitation hypotheses. The former states that treeline trees have an unfavorable carbon balance and cannot support growth of the magnitude observed at lower elevations or latitudes, while the latter argues that treeline trees have an adequate carbon supply, but that cold temperatures directly limit growth. In this study, we examined the relative importance of source and sink limitation in forest and treeline white spruce (Picea glauca) in three mountain ranges from southern to northern Alaska.

Population density of North American elk: effects on plant diversity.

Large, herbivorous mammals have profound effects on ecosystem structure and function and often act as keystone species in ecosystems they inhabit. Density-dependent processes associated with population structure of large mammals may interact with ecosystem functioning to increase or decrease biodiversity, depending on the relationship of herbivore populations relative to the carrying capacity (K) of the ecosystem. We tested for indirect effects of population density of large herbivores on plant species richness and diversity in a montane ecosystem, where increased net aboveground primary productivity (NAPP) in response to low levels of herbivory has been reported.