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Warmer climatic conditions have been associated with numerous hydrologic changes that may impact riverbank erosion in cold regions, but the net effect is not well understood. We used regression and correlation analyses to examine the relationships among subarctic riverbank erosion and seasonal hydrology, the impact of climate change and variability, and the societal implications. Geomorphic change (loss and gain of vegetated land) was mapped along several river reaches in the Yukon River Basin, Alaska, throughout 1984 and 2017 using Landsat satellite imagery. Annual erosion rates were estimated from these spatial data. At most study sites, erosion rates (km2/year) were either positively correlated (r = 0.68–0.84, p = 0.0085–0.061) with monthly mean discharge within the cold season or inversely correlated (r = − 0.74 – −0.62, p

The Central Arctic Caribou (Rangifer tarandus) Herd (CACH) of Arctic Alaska rapidly declined (approximately 70%) between 2010–2016, which has generated hunter concerns and more conservative hunting...

The traditional harvest of wild resources carries significant nutritional, economic, and sociocultural values for rural residents in the Arctic, especially for Indigenous subsistence communities. Rural communities in the Alaskan Arctic have expressed concern that aircraft activity from industry, commercial hunting, research, and tourism disrupts their harvest of wildlife, particularly caribou (Rangifer tarandus). However, little research exists on how aircraft impact harvest opportunities. Our objective was to assess the extent of scientific knowledge on aircraft-harvester interaction in the Arctic through a systematic search of the available literature. We found that no peer-reviewed publications addressed the conflict between aircraft and harvesters in the region. Some literature addressed aircraft impacts to subsistence species, but did not discuss how those impacts would affect local harvesters. Most research has been directed towards studying aircraft impacts on wildlife or humans in urbanized areas rather than in rural, subsistence communities. Therefore, we expanded our review to draw from gray literature (e.g., public records, government documents) to synthesize the current state of concern and perceptions on aircraft disturbance to subsistence harvesters. Based on the gray literature, we found that harvester frustrations were primarily directed toward low-flying aircraft and non-local operations. However, an absence of quantitative information on the extent of interaction between aircraft activity and harvesters hinders an objective assessment of the conflict. Mitigating conflict will require research focused on this data gap and may begin with better cooperation among rural communities, aircraft users, and decision-makers.

Ecosystems across the United States are changing in complex and unpredictable ways and analysis of these changes requires coordinated, long‐term research. This paper is a product of a synthesis effort of the U.S. National Science Foundation funded Long‐Term Ecological Research (LTER) network addressing the LTER core research area of “populations and communities.” This analysis revealed that each LTER site had at least one compelling “story” about what their site would look like in 50–100 yr. As the stories were prepared, themes emerged, and the stories were group into papers along five themes: state change, connectivity, resilience, time lags, and cascading effects. This paper addresses the cascading effects theme and includes stories from the Bonanza Creek (boreal), Kellogg Biological Station (agricultural and freshwater), Palmer (Antarctica), and Harvard Forest (temperate forest) LTER sites. We define cascading effects very broadly to include a wide array of unforeseen chains of events that result from a variety of actions or changes in a system. While climate change is having important direct effects on boreal forests, indirect effects mediated by fire activity—severity, size, and return interval—have large cascading effects over the long term. In northeastern temperate forests, legacies of human management and disturbance affect the composition of current forests, which creates a cascade of effects that interact with the climate‐facilitated invasion of an exotic pest. In Antarctica, declining sea ice creates a cascade of effects including declines in Adèlie and increases in Gentoo penguins, changes in phytoplankton, and consequent changes in zooplankton populations. An invasion of an exotic species of lady beetle is likely to have important future effects on pest control and conservation of native species in agricultural landscapes. New studies of zebra mussels, a well‐studied invader, have established links between climate, the heat tolerance of the mussels, and harmful algal blooms. Collectively, these stories highlight the need for long‐term studies to sort out the complexities of different types of ecological cascades. The diversity of sites within the LTER network facilitates the emergence of overarching concepts about trophic interactions as an important driver of ecosystem structure, function, services, and futures.

The Colville River is the largest river basin (∼53,000 km2) in Alaskan Arctic. The residents of Nuiqsut, an established Alaska Native community of ∼400 people, rely heavily on the Colville for their subsistence needs. Nonetheless, the changing river dynamics caused by accelerated bank erosion and consequent river siltation is making travel on the Colville increasingly difficult and in some cases dangerous. We used summer 2017 scenes from three optical sensors (PlanetScope, Sentinel 2, and Landsat) with resolution ranging from 3–30 m along with field measurements of water-depth to map shallow-water sites along a 45-km stretch of the Colville River. We found a strong correlation ( $\mathrm{R}^{2}=0.9$ ) between field-measured water depths and image-derived reflectance quantity (natural log ratio of green over red bands). We also analyzed a relative depth mapping technique which can be used to map shallow-water sites from optical images in the absence of field-measured water depths.

Alaska moose (Alces alces) hunters have expressed concern that harvest has been challenged by warmer temperatures altering moose behavior and low water levels limiting boat access to hunting areas. The environmental impacts of these changes on moose harvest have not been quantified and are not well understood. Our objective was to assess how environmental conditions impact hunter harvest in Interior Alaska from 2000-2016. We split hunters into categories (local or non-local) and analyzed relationships during 5-day blocks that spanned the moose hunting season. The local harvest model associated high water level with increased harvest during block 4 (peak-harvest) of the hunting season (p = 0.006). A water level increase of 1 m increased daily harvest by 1.5 (p = 0.003). Non-local harvest was significantly different than null models for block 2 (p = 0.001), 3 (p = 0.048), and 4 (p = 0.001), and nearly in block 5 (p = 0.063). The non-local harvest model associated an increase in mean high temperature with reduced harvest in block 2 (p = 0.004) and block 5 (p = 0.037), and an increase in water level with increased harvest in block 3 (p = 0.083), 4 (p = 0.017), and block 5 (p = 0.092). These results reveal that local and non-local hunters are impacted differently by environmental conditions throughout the hunting season. We provided quantitative information on previously untested hypotheses regarding the impacts of dynamic environmental conditions on moose hunter harvest. Our findings provide wildlife managers with new insight on causes of variation in harvest among different user groups.

Although extensive research has been conducted on a variety of factors that influence wildlife harvest rates, few studies have quantified the impact of weather on harvest success. As global warming continues to contribute to unprecedented changes in local weather regimes, particularly in arctic and alpine ecosystems, understanding how these changes impact human–wildlife interactions will become increasingly important and relevant for wildlife managers. Therefore, we used a long-term dataset (1999–2015) on Dall's sheep Ovis dalli dalli, an alpine species in Alaska, USA, as a case study to explore how changes in local daily weather has affected hunter harvest success. We used generalized linear mixed models to estimate relationships between daily harvest count and weather variables using three separate models; all hunters, resident hunters and non-resident hunters. Weather variables included daily mean relative humidity, precipitation, air temperature and wind speed. For our model including all hunters, which excluded wind, we estimated that a mean increase in relative humidity, precipitation and temperature from one day to the next resulted in an 11.7, 4.3 and 2.9% decrease in daily harvest, respectively. The effect of relative humidity influenced harvest count two to three times more than all other weather variables across models. This study contributes to a limited body of knowledge on quantifying the impact of weather on harvest success and about how changes in weather affect hunter and wildlife behavior. Advancing knowledge on how weather influences variation in harvest may facilitate effective strategies for adapting hunting regulations to meet harvest and population goals.

Subsistence harvesters in high latitudes rely on frozen rivers for winter access to local resources. During recent decades, interior Alaskan residents have observed changes in river ice regimes that are significant hindrances to travel and subsistence practices. We used remote sensing in combination with local observations to examine changes in seasonality of river breakup and freeze-up and to assess the implications on travel for subsistence harvesters. Spring and autumn air temperatures, respectively, were found to impact timing of breakup (−2.0 days °C−1) and freeze-up (+2.0 days °C−1). Spring air temperatures have increased by 0.2°–0.6°C decade−1 over the last 62–93 years, depending on study area and time period. Local observations indicate that the breakup season has advanced by about 6 days over the last century. Autumn air temperatures have not changed over the long term, but have been generally warmer over the last 15 years. Over various time periods throughout the last century, we found no change in freeze-up timing for some communities, whereas other communities showed delays of 1.0–2.1 days decade−1. The length of time the river was unsafe for travel during the freeze-up season was 2 to 3 times greater than during breakup. The duration of river ice cover for safe travel has declined over the last century and is expected to decline further as the climate continues to warm, thereby presenting new challenges to accessing subsistence resources and necessitating community adaptation.

Fire severity is an important control over regeneration of deciduous species and can influence the overall quality of habitat for herbivores, such as moose (Alces alces (Linnaeus, 1758)), but the relationships between availability and duration of biomass production and moose habitat use are largely unknown. We evaluate the relative influence of a regenerating burn, paying particular attention to fire severity, on winter forage production and duration, offtake, nutritional quality, and seasonal moose habitat use. We used data from 14 GPS collared male moose in the 20-year-old Hajdukovich Creek Burn (HCB) in interior Alaska, USA, to generate seasonal dynamic Brownian bridge movement models. Within HCB, moose selected for low-severity sites more than high- and moderate-severity sites during the winter. Over the past decade, willow (species of the genus Salix L.) biomass production in low-severity sites has doubled and is likely influencing winter habitat selection patterns. In summer, moose selected for high-severity sites where there is a more abundant understory layer (e.g., stem densities) providing both forage and cover. The initial pulse of biomass production in high-severity sites, as well as the delay in growth and maturation of vegetation in low-severity sites, indicate that differing distributions of wildfire severity can create a dynamic mosaic of habitat patches that may extend the value of burns over time for moose.

Liberalized harvest of antlerless moose (Alces alces) in Alaska has resulted in conflict between wildlife managers and hunters. To address this issue, I surveyed moose hunters (n = 845, 35%...

The functional response is the relationship between food intake rates and prey density, and is shaped by factors including handling time, predator speed, habitat or prey movement. For many predator—prey systems, the density-dependent functional response is represented by a type II or type III functional response. Determination of the relationship type is important, as managers can often predict the response of predators to changing prey densities. In wolf—moose (Canis lupus—Alces alces) systems with relatively high prey density, the functional response often follows a predicted type II functional response. However, in a very low prey-density system, wolves have previously been shown to escape the density dependent phase of the functional response and demonstrated kill rates mimicking high prey-density systems. We conducted a study to evaluate winter wolf movements between moose kills in the Yukon Flats, Alaska where moose exist at densities

Amplified climate change in the Arctic has altered interactions between rural communities and local wild resources. Shifting interactions warrant analysis because they can influence cultural practices and food security of northern societies. We collaborated with four indigenous communities in Alaska and conducted semi-directed interviews with 71 experienced harvesters to identify local perceptions of climate-driven trends in the environment, and describe the effects of those trends on the availability (i.e., abundance, distribution, accessibility) of subsistence resources. We then linked local perceptions with scientific climate projections to forecast how availability of subsistence resources may change in the future. Hunters identified 47 important relationships between climate-driven changes in the environment and availability of subsistence resources. Of those relationships, 60, 28, and 13 % focused on changes in harvester access, resource distribution, and resource abundance, respectively. Our forecast model indicated a net reduction in the availability of subsistence resources over the next 30 years. The reduction was caused primarily by climate-related challenges in access, rather than changes in abundance or distribution of resources. Our study demonstrates how giving insufficient attention to harvester access may produce misleading conclusions when assessing the impacts of climate change on future subsistence opportunities.

This paper describes the integration of social–ecological science with traditional knowledge to address global-change challenges faced by indigenous communities in rural Alaska. The Community Partnership for Self-Reliance is a novel boundary organization that uses community visions for self-reliance, based on local and traditional knowledge, to link bottom-up with top-down adaptation planning. We suggest that similar boundary strategies can improve the communication of adaptation needs and opportunities across scales, empowering local communities to select adaptation choices that fit their own goals. This would facilitate regional experimentation and diffusion of innovative solutions to address rapid and heterogeneous environmental and socioeconomic change.

Energy costs are large and increasing in rural Alaska communities, so communities are turning to renewable energy. While, many of these communities have a mixed subsistence-cash economy, the relationship between renewable energy and subsistence has not been studied. Tanana, Alaska has a biomass program and we conducted interviews with 61 households in 2017 to understand how residents perceive the program and its association with subsistence activities. We analyzed Alaska Department of Fish & Game subsistence surveys from 89 communities to estimate differences in subsistence harvest between households that harvest wood and those that do not. Interviews indicated that people who harvest wood for the biomass program were six times more likely to engage in subsistence. Subsistence harvests were nearly double (184 kg/per capita) in households that harvested wood for personal use versus those that did not (101 kg/per capita). Equipment used for both activities was similar, and 57% respondents combined wood harvesting with other activities (e.g. subsistence, travel, etc.). Higher household incomes and employment were positively associated with subsistence participation (p

Despite hunter access influencing harvest success, few studies have quantified characteristics of hunter access. Based on spatially explicit interview data, we used geographic information system (GIS) analyses to calculate access pathways and distances that rural hunters traveled to moose (Alces alces) harvest locations in Interior Alaska. Using Jenks Natural Breaks classification, approximately 53%, 21%, 5%, and 21% of harvest locations occurred along navigable rivers within 0 to 24, 25 to 52, 53 to 86, and >86 km (0 to 14, 15 to 32, 33 to 53, and >53 mi), respectively, from the hunter’s community of residence. We used moose density estimates in the area being accessed by hunters to calculate annual moose harvest. Our results were similar to estimates from independent sources that used more standardized methods (e.g., agency household surveys). This suggests that our access-based approach has potential to provide an alternative method for estimating harvest intensity in areas where harvest report...

We synthesized an expert review of climate change implications for hydroecological and terrestrial ecological systems in the northern coastal temperate rainforest of North America. Our synthesis is based on an analysis of projected temperature, precipitation, and snowfall stratified by eight biogeoclimatic provinces and three vegetation zones. Five IPCC CMIP5 global climate models (GCMs) and two representative concentration pathways (RCPs) are the basis for projections of mean annual temperature increasing from a current average (1961–1990) of 3.2 °C to 4.9–6.9 °C (5 GCM range; RCP4.5 scenario) or 6.4–8.7 °C (RCP8.5), mean annual precipitation increasing from 3130 mm to 3210–3400 mm (3–9 % increase) or 3320–3690 mm (6–18 % increase), and total precipitation as snow decreasing from 1200 mm to 940–720 mm (22–40 % decrease) or 720–500 mm (40–58 % decrease) by the 2080s (2071–2100; 30-year normal period). These projected changes are anticipated to result in a cascade of ecosystem-level effects including: increased frequency of flooding and rain-on-snow events; an elevated snowline and reduced snowpack; changes in the timing and magnitude of stream flow, freshwater thermal regimes, and riverine nutrient exports; shrinking alpine habitats; altitudinal and latitudinal expansion of lowland and subalpine forest types; shifts in suitable habitat boundaries for vegetation and wildlife communities; adverse effects on species with rare ecological niches or limited dispersibility; and shifts in anadromous salmon distribution and productivity. Our collaborative synthesis of potential impacts highlights the coupling of social and ecological systems that characterize the region as well as a number of major information gaps to help guide assessments of future conditions and adaptive capacity.

Winters are limiting for many terrestrial animals due to energy deficits brought on by resource scarcity and the increased metabolic costs of thermoregulation and traveling through snow. A better understanding of how animals respond to snow conditions is needed to predict the impacts of climate change on wildlife. We compared the performance of remotely sensed and modeled snow products as predictors of winter movements at multiple spatial and temporal scales using a data set of 20,544 locations from 30 GPS-collared Dall sheep (Ovis dalli dalli) in Lake Clark National Park and Preserve, Alaska, USA from 2005 to 2008. We used daily 500-m MODIS normalized difference snow index (NDSI), and multi-resolution snow depth and density outputs from a snowpack evolution model (SnowModel), as covariates in step selection functions. We predicted that modeled snow depth would perform best across all scales of selection due to more informative spatiotemporal variation and relevance to animal movement. Our results indicated that adding any of the evaluated snow metrics substantially improved model performance and helped characterize winter Dall sheep movements. As expected, SnowModel-simulated snow depth outperformed NDSI at fine-to-moderate scales of selection (step scales 300 kg/m3 ) at snow depths above chest height, which likely further reduced energy expenditure by limiting hoof penetration in deeper snows. At moderate-to-coarse scales (112-896 h step scales), however, NDSI was the best-performing snow covariate. Thus, the use of publicly available, remotely sensed, snow cover products can substantially improve models of animal movement, particularly in cases where movement distances exceed the MODIS 500-m grid threshold. However, remote sensing products may require substantial data thinning due to cloud cover, potentially limiting its power in cases where complex models are necessary. Snowpack evolution models such as SnowModel offer users increased flexibility at the expense of added complexity, but can provide critical insights into fine-scale responses to rapidly changing snow properties.

Most rural residents in Arctic communities rely on motorized transportation to hunt, fish, trap, and gather subsistence resources. Although these technologies have created advantages, one significant disadvantage is that peoples' ability to meet their nutritional and cultural needs now depends on consistent opportunities for wage employment and availability of affordable fuel. Recent qualitative research suggested that rising fuel prices have disrupted subsistence lifestyles in the Arctic. Our objectives were to collaborate with subsistence users in rural Alaskan communities to quantify how rising fuel costs have impacted subsistence activities and explore ways local residents may adapt to the trajectory of change. We conducted interviews with 178 subsistence harvesters in 8 communities. During the last 10 years, 81% of the harvesters reduced the distance they traveled for subsistence and 89% reduced the number of subsistence trips they took because of gasoline costs. During the last 10 years, the median distance traveled to perform subsistence decreased by 60%, and the median annual number of trips taken to perform subsistence decreased by 75%. The change in subsistence activity was similar across and within communities. Eighty-five percent of the people interviewed reported that they were making sacrifices with serious consequences, such as putting off paying monthly bills, to buy gasoline for subsistence activities. To adapt to high gasoline prices, most participants said that they are using more efficient modes of transportation (69%), followed by more sharing of gasoline costs with family and friends (37%), and conducting more multipurpose subsistence trips (20%). With subsistence practices being critical to food security and cultural identity in the Arctic, our results suggest that unaffordable fuel has threatened social resilience. Because global markets drive gasoline prices, we suggest that future research focus on the effectiveness of adaptation options that build resilience into subsistence systems.