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The Matanuska-Susitna Borough is the fastest growing region in the State of Alaska and is impacted by a number of human activities. We conducted a multiscale assessment of the stressors facing the borough by developing and mapping the Index of Watershed Integrity (IWI) and Index of Catchment Integrity (the latter considers stressors in areas surrounding individual stream segments exclusive of upstream areas). The assessment coincided with the borough's stormwater management planning. We adapted the list of anthropogenic stressors used in the original conterminous United States IWI application to reflect the borough's geography, human activity, and data availability. This analysis also represents an early application of the NHDPlus High Resolution geospatial framework and the first use of the framework in an IWI study. We also explored how remediation of one important stressor, culverts, could impact watershed integrity at the catchment and watershed scales. Overall, we found that the integrity scores for the Matanuska-Susitna basin were high compared to the conterminous United States. Low integrity scores did occur in the rapidly developing Wasilla-Palmer core area. We also found that culvert remediation had a larger proportional impact in catchments with fewer stressors.

Plant associated mutualists can mediate invasion success by affecting the ecological niche of nonnative plant species. Anthropogenic disturbance is also key in facilitating invasion success through changes in biotic and abiotic conditions, but the combined effect of these two factors in natural environments is understudied. To better understand this interaction, we investigated how disturbance and its interaction with mycorrhizas could impact range dynamics of nonnative plant species in the mountains of Norway. Therefore, we studied the root colonisation and community composition of arbuscular mycorrhizal (AM) fungi in disturbed vs undisturbed plots along mountain roads. We found that roadside disturbance strongly increases fungal diversity and richness while also promoting AM fungal root colonisation in an otherwise ecto‐mycorrhiza and ericoid‐mycorrhiza dominated environment. Surprisingly, AM fungi associating with nonnative plant species were present across the whole elevation gradient, even above the highest elevational limit of nonnative plants, indicating that mycorrhizal fungi are not currently limiting the upward movement of nonnative plants. We conclude that roadside disturbance has a positive effect on AM fungal colonisation and richness, possibly supporting the spread of nonnative plants, but that there is no absolute limitation of belowground mutualists, even at high elevation. ISSN:0028-646X ISSN:1469-8137

The distribution and composition of Arctic vegetation are expected to shift with ongoing climate change. Global models generally predict northward shifts in high‐latitude ecotones, and analysis of remote sensing data shows widespread greening and changes in vegetation structure across the circumpolar Arctic. However, there are still uncertainties related to the timing of these shifts and variation among different plant functional types. In this paper, we investigate disequilibrium dynamics of green alder and white spruce in the Tuktoyaktuk Coastal Plain, NWT. We used high‐resolution air photographs captured in the 1970s and 2000s to quantify changes in the distribution and abundance of alder and spruce near their northern limits. We found increases in alder and spruce stem density over time, but no change in their range limits, indicating that both species are affected by leading‐edge disequilibrium. Low stand density and temperature limitation of reproduction along the northern margin likely contributed to observed disequilibrium in both species. We also observed the greatest change in species occupancy within a burned area, suggesting that the increased frequency of fire will play a significant role in the timing and magnitude of near‐term vegetation change.

A dietary transition away from traditional foods and toward a diet of the predominantly unhealthy market is a public health and sociocultural concern throughout Indigenous communities in Canada, including those in the sub-Arctic and remote regions of Dehcho and Sahtú of the Northwest Territories, Canada. The main aim of the present study is to describe dietary intakes for macronutrients and micronutrients in traditional and market food from the Mackenzie Valley study. We also show the trends of contributions and differences of dietary intakes over time from 1994 data collected and reported by the Centre for Indigenous People’s Nutrition and Environment (CINE) in 1996. Based on 24-h dietary recall data, the study uses descriptive statistics to describe the observed dietary intake of the Dene First Nations communities in the Dehcho and Sahtú regions of the NWT. Indigenous people in Canada, like the sub-Arctic regions of Dehcho and Sahtú of the NWT, continue to consume traditional foods, although as a small percentage of their total dietary intake. The observed dietary intake calls for action to ensure that traditional food remains a staple as it is critical for the wellbeing of Dene in the Dehcho and Sahtú regions and across the territory.

Context: ‘Conserving Nature’s stage’ has been advanced as an important conservation principle because of known links between biodiversity and abiotic environmental diversity, especially in sensitive high-latitude environments and at the landscape scale. However these links have not been examined across gradients of human impact on the landscape. Objectives: To (1) analyze the relationships between land-use intensity and both landscape-scale biodiversity and geodiversity, and (2) assess the contributions of geodiversity, climate and spatial variables to explaining vascular plant species richness in landscapes of low, moderate and high human impact. Methods: We used generalized additive models (GAMs) to analyze relationships between land-use intensity and both geodiversity (geological, geomorphological and hydrological richness) and plant species richness in 6191 1-km² grid squares across Finland. We used linear regression-based variation partitioning (VP) to assess contributions of climate, geodiversity and spatial variable groups to accounting for spatial variation in species richness. Results: In GAMs, geodiversity correlated negatively, and plant species richness positively, with land-use intensity. Both relationships were non-linear. In VP, geodiversity best accounted for species richness in areas of moderate to high human impact. These overall contributions were mainly due to variation explained jointly with climate, which dominated the models. Independent geodiversity contributions were highest in pristine environments, but low throughout. Conclusions: Human action increases biodiversity but may reduce geodiversity, at landscape scale in high-latitude environments. Better understanding of the connections between biodiversity and abiotic environment along changing land-use gradients is essential in developing sustainable measures to conserve biodiversity under global change.

Sub-arctic birch forests (Betula pubescens Ehrh. ssp. czerepanovii) periodically suffer large-scale defoliation events caused by the caterpillars of the geometrid moths Epirrita autumnata and Operophtera brumata. Despite their obvious influence on ecosystem primary productivity, little is known about how the associated reduction in belowground C allocation affects soil processes. We quantified the soil response following a natural defoliation event in sub-arctic Sweden by measuring soil respiration, nitrogen availability and ectomycorrhizal fungi (EMF) hyphal production and root tip community composition. There was a reduction in soil respiration and an accumulation of soil inorganic N in defoliated plots, symptomatic of a slowdown of soil processes. This coincided with a reduction of EMF hyphal production and a shift in the EMF community to lower autotrophic C-demanding lineages (for example, /russula-lactarius). We show that microbial and nutrient cycling processes shift to a slower, less C-demanding state in response to canopy defoliation. We speculate that, amongst other factors, a reduction in the potential of EMF biomass to immobilise excess mineral nitrogen resulted in its build-up in the soil. These defoliation events are becoming more geographically widespread with climate warming, and could result in a fundamental shift in sub-arctic ecosystem processes and properties. EMF fungi may be important in mediating the response of soil cycles to defoliation and their role merits further investigation. Electronic supplementary material The online version of this article (doi:10.1007/s10021-016-0026-7) contains supplementary material, which is available to authorized users.

Rapid climate change in Arctic regions is resulting in more frequent extreme climatic events. These can cause large-scale vegetation damage, and are therefore among key drivers of declines in biomass and productivity (or “browning”) observed across Arctic regions in recent years. Extreme events which cause browning are driven by multiple interacting climatic variables, and are defined by their ecological impact – most commonly plant mortality. Quantifying the climatic causes of these multivariate, ecologically defined events is challenging, and so existing work has typically determined the climatic causes of browning events on a case-by-case basis in a descriptive, unsystematic manner. While this has allowed development of important qualitative understanding of the mechanisms underlying extreme event driven browning, it cannot definitively link browning to specific climatic variables, or predict how changes in these variables will influence browning severity. It is therefore not yet possible to determine how extreme events will influence ecosystem responses to climate change across Arctic regions. To address this, novel, process-based climate metrics that can be used to quantify the conditions and interactions that drive the ecological responses defining common extreme events were developed using publicly available snow depth and air temperature data (two of the main climate variables implicated in browning). These process-based metrics explained up to 63% of variation in plot-level Normalised Difference Vegetation Index (NDVI) at sites within areas affected by extreme events across boreal and sub-Arctic Norway. This demonstrates potential to use simple metrics to assess the contribution of extreme events to changes in Arctic biomass and productivity at regional scales. In addition, scaling up these metrics across the Norwegian Arctic region resulted in significant correlations with remotely-sensed NDVI, and provided much-needed insights into how climatic variables interact to determine the severity of browning across Arctic regions.

Biomagnification (increase in contaminant concentrations at successively higher levels of trophic web), is a process that can transversally impair biodiversity and human health. Most research shows that biomagnification should be higher at poles with northern sites having a major tendency to biomagnify Persistent Organic Pollutants (POPs) through their marine food webs. We investigated the biomagnification degree into two marine trophic webs combining carbon and nitrogen stable isotopes and POP analyses. We showed that the Antarctic trophic web was more depleted than the sub-Arctic one and the differences highlighted for the basal part could explain the difference in length between them. Concentrations of polychlorinated biphenyls (PCBs), hexachlorobenzene (HCB), and p,p’-DDE were of the same order of magnitude in the two polar trophic webs, with some values surprisingly higher in the Antarctic than sub-arctic organisms: PCBs ranged (average ± standard deviation) 1.10 ± 0.39–12.93 ± 7.62, HCB

The Arctic and the surrounding region of the sub-Arctic represent a key area for the study of global change because the anthropogenic impact, particularly the rate of warming, is projected to be the greatest in any part of the world due to the complicated feedback processes which occur. This Arctic region has undergone very large changes in recent years due to global warming, and accelerated change is predicted. The rapid changes that are occurring in the Arctic, and that have been the topic of the ISAR-1 and ISAR-2 conferences, manifest themselves at a number of scales. The large scales are Arctic-wide changes in key environmental parameters, which are described in a series of papers in this issue. On a more subtle scale we see changes to species and to biological processes in the Arctic. We hope that readers will enjoy the range of papers published in this issue, and will appreciate that phenomena ranging in scale from global radiation balance to clutch size of birds' eggs are actually all related via the central fact of the present-day Arctic, its high rate of warming.

This study uses an airborne Light Detection and Ranging (LiDAR) survey, historical aerial photography and historical climate data to describe the character and dynamics of the Nogahabara Sand Dunes, a sub-Arctic dune field in interior Alaska’s discontinuous permafrost zone. The Nogahabara Sand Dunes consist of a 43-km2 area of active transverse and barchanoid dunes within a 3200-km2 area of vegetated dune and sand sheet deposits. The average dune height in the active portion of the dune field is 5.8 m, with a maximum dune height of 28 m. Dune spacing is variable with average crest-to-crest distances for select transects ranging from 66–132 m. Between 1952 and 2015, dunes migrated at an average rate of 0.52 m a−1. Dune movement was greatest between 1952 and 1978 (0.68 m a−1) and least between 1978 and 2015 (0.43 m a−1). Dunes migrated predominantly to the southeast; however, along the dune field margin, net migration was towards the edge of the dune field regardless of heading. Better constraining the processes controlling dune field dynamics at the Nogahabara dunes would provide information that can be used to model possible reactivation of more northerly dune fields and sand sheets in response to climate change, shifting fire regimes and permafrost thaw.

Seacoast to inland soil transects of 1 and 2 km were researched over 2 years to understand the microbial diversity in a post ice age, isostatically, rebounding, soil environment. Community level substrate utilization analysis and 16S rDNA eubacterial diversity were employed. The community level substrate analysis demonstrated that regardless of the location along the transect from seacoast to forest, sandy or peat soil, the microbial diversity (Shannon diversity index about 3) was virtually the same. Shannon diversity indexes based on PCR-DGGE analysis yielded values between about 0.6 and about 2 depending on the sand or peat soil type and the year the samples were collected and analyzed (2002 and 2003). Regardless of the genetic diversity, the soils exhibited similar metabolic capabilities. This is a good example of redundant, functional, physiology regardless of the species present at each location along the transects.

The sea urchin Strongylocentrotus droebachiensis and the scallop Chlamys islandica dominate the shallow macrobenthic community in Kobbefjord, southwest Greenland (64° 09’ N, 51° 36’ W). Densities were estimated from seafloor photographs along 3 depth transects (0 to 120 m). Annually formed growth bands in the interambulacral plates of S. droebachiensis and in the ligament of C. islandica were used to establish growth functions. Growth data combined with size frequencies, size–mass relationships and fjord bathymetry were used to estimate annual production and carbon demand of the 2 species in order to assess their ecological importance. Distributions of the 2 species were strongly related to depth and partially separated. Averaged over all depths, the densities were estimated at 4.9 ind. m–2 (range: 0 to 38 ind. m–2) and 5.6 ind. m–2 (range: 0 to 57 ind. m–2) for S. droebachiensis and C. islandica, respectively. Maximum ages of S. droebachiensis and C. islandica were estimated at 24 and 39 yr, respectively. Somatic growth of both species was relatively slow, and their reproductive output constituted the bulk (62 to 73%) of their total annual production. Mean annual production in the fjord was estimated at 3.2 g ash-free dry weight (AFDW) m–2 for S. droebachiensis and 2.5 g AFDW m–2 for C. islandica. The total annual carbon demand of the 2 species was estimated at 30.6 g C m–2, corresponding to 21–45% of annual pelagic primary production in this area. In conclusion, S. droebachiensis and C. islandica play important roles in carbon cycling of Kobbefjord and can be regarded as central species of the shallow benthic community. A comparison with literature estimates of annual macrozoobenthic carbon demand in Arctic and sub-Arctic habitats revealed that the macrozoobenthic carbon demand in Kobbefjord is relatively high and that annual carbon requirements of macrozoobenthos in the Arctic seem to reflect the level of pelagic primary production.

International audience; Grey seals Halichoerus grypus were sampled in the Faroe Islands archipelago during the summers of 1993 to 1995. Concentrations of Cd, Cu, Hg, Se and Zn were measured in the liver, kidney and muscle of 68 seals. All elements except Zn exhibited lowest concentrations in the muscle. The liver contained the highest concentrations of Cu, Hg, Se and Zn, while the kidney contained the highest Cd concentrations. However, trace element concentrations within the tissues were influenced by sex and age. Thus, females had clearly higher Cd concentrations than males. Age was the most important factor influencing the concentration of Cd, Hg and Se in the liver, and of Cd and Hg in the kidney. A strong positive correlation between Cd, Hg and Zn in the kidney suggests the presence of a detoxification process involving metallothionein proteins. Similarly, a strong positive correlation between Hg and Se and a molecular Hg:Se ratio close to 1 in the liver suggests a demethylation process leading to the formation of mercuric selenide granules. High Hg concentrations could be related to fish consumption by the grey seal, but a piscivorous diet could not be responsible for the very high Cd concentrations. This suggests that the seals¹ diet changes during the year, and may include a significant proportion of cephalopods in seasons other than summer. Finally very high Cd concentrations in grey seal tissues compared to other grey seal populations also suggest that the Faroe Islands are subject to sub-arctic influences.

Four krill species with overlapping functional biology coexist in Greenland waters. Here, we used stable isotopes to investigate and discuss their trophic role and mode of coexistence. Bulk carbon (δ13C) and nitrogen (δ15N) stable isotope analyses of Thysanoessa longicaudata, T. inermis, T. raschii and Meganyctiphanes norvegica sampled in June 2010 in Godthåbsfjord, SW Greenland, revealed new insight into the species’ trophic roles and positions. There was a general positive correlation between body length and trophic position. The largest species, M. norvegica, had the highest trophic position (TP [mean ± SE] = 2.8 ± 0.2) indicating carnivory, while T. inermis (TP = 2.4 ± 0.3) had a more omnivorous diet. In turn, T. longicaudata and T. raschii (TP = 2.2 ± 0.2) were herbivorous. Along the fjord, plankton composition affected trophic position. T. longicaudata was more omnivorous offshore than inshore, where it had the same trophic position as the baseline primary consumer Calanus spp. Similarly, T. raschii and T. inermis had higher trophic positions in the mouth of the fjord compared with the inner fjord. Regardless of spatial variations in potential food and the overlap in diet, typical of opportunistic species, body size appears as the key factor determining the role and position of krill in the food web., Project BOFYGO (Danish Centre for Marine Research), EUROBASIN (7FP EU ENV.2010.2.2.1-1 grabt agreement 264933), Greenland Climate Centre (Project 6505), 2,4830

Filarioid parasites represent major health hazards with important medical, veterinary, and economic implications, and considerable potential to affect the everyday lives of tens of millions of people globally (World Health Organization, 2007). Scenarios for climate change vary latitudinally and regionally and involve direct and indirect linkages for increasing temperature and the dissemination, amplification, and invasiveness of vector-borne parasites. High latitude regions are especially influenced by global climate change and thus may be prone to altered associations and dynamics for complex host-pathogen assemblages and emergence of disease with cascading effects on ecosystem structure. Although the potential for substantial ecological perturbation has been identified, few empirical observations have emanated from systems across the Holarctic. Coincidental with decades of warming, and anomalies of high temperature and humidity in the sub-Arctic region of Fennoscandia, the mosquito-borne filarioid nematode Setaria tundra is now associated with emerging epidemic disease resulting in substantial morbidity and mortality for reindeer and moose. We describe a host-parasite system that involves reindeer, arthropods, and nematodes, which may contribute as a factor to ongoing declines documented for this ungulate species across northern ecosystems. We demonstrate that mean summer temperatures exceeding 14 degrees C drive the emergence of disease due to S. tundra. An association between climate and emergence of filarioid parasites is a challenge to ecosystem services with direct effects on public health, sustainability of free-ranging and domestic ungulates, and ultimately food security for subsistence cultures at high latitudes.

Climate change may affect bird populations both directly by changing the weather conditions, and indirectly through changes in the food chain. While both theoretical and empirical studies have shown climate change having drastic impacts on polar areas, its consequences on Arctic bird species are still poorly known. Here we investigated how weather and changes in predator–prey interactions affected the annual growth rates of sub-Arctic birds by monitoring the breeding numbers of three duck and seven wader species in the alpine tundra of Finnish Lapland during 2005–2015 (except for 2006). We hypothesized that growth rates of waterbirds would be positively associated with warm and dry weather due to improved reproductive success. Furthermore, we tested the hypothesis that waterbirds have a higher reproductive success during the cyclic rodent peaks, when predators mainly prey on rodents, than during the decline and low phases of the cycle, when predation pressure towards waterbirds increases. Results showed that population growth rates of breeding ducks were negatively associated with the sum of rainfall in the previous year. In waders, growth rates were positively associated with the phase of the rodent cycle in the same year. Our results emphasize the importance of monitoring Arctic bird populations on their breeding areas to explore what the consequences of climate change might be for breeding waterbirds by linking the effects of both weather and rodent abundance. peerReviewed

International audience; Recognition and characterisation of built-ups in the Siberian sub-Arctic urban territories as Yakutsk are dependant of two main factors: (1) season (snow and ice from October to the end of April, the flooding period in May, and the summertime), which influence the accuracy of urban objects detection. (2) Urban structure, which influence the morphological recognition and characterisation of built-ups. In this study, high repetitiveness remote sensing Sentinel-2 and SPOT 6 high-resolution satellite images are combined to characterise and detect urban built-ups over Yakutsk city. High temporal resolution of Sentinel-2 allows land use change detection and metric spatial resolution of SPOT 6 allows the characterisation of built-ups socio-economic functions and uses.