Unified Ecoregions of Alaska: 2001

Nowacki, Gregory J.; Spencer, Page; Fleming, Michael J.; Brock, Terry; Jorgenson, T.

doi:10.3133/ofr2002297

Cited by 88 publications

(114 citation statements)

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“…1, Nowacki et al, 2001). The region transitions from treeless arctic tundra in the north and west to black spruce (Picea mariana) stands and eventually to boreal deciduous forests in the south and east.…”

Section: Study Areamentioning

confidence: 99%

“…The ground of the Brooks Foothills, to the south, is composed of thick continu¬ ous permafrost and supports no trees. Low shrubs, sedges, and tussock tundra dominate this region but extensive willow thickets line the many braided rivers and streams (Nowacki et al, 2001). The steep angular peaks of the Brooks Range are largely barren, while alpine vegetation can be found at lower eleva¬ tions (Nowacki et al, 2001).…”

Section: Study Areamentioning

confidence: 99%

“…Low shrubs, sedges, and tussock tundra dominate this region but extensive willow thickets line the many braided rivers and streams (Nowacki et al, 2001). The steep angular peaks of the Brooks Range are largely barren, while alpine vegetation can be found at lower eleva¬ tions (Nowacki et al, 2001). Forests and woodlands dominate much of the Kobuk Ridge and Valley ecoregion on the southern flanks of the Brooks Range (Nowacki et al, 2001).…”

Section: Study Areamentioning

confidence: 99%

“…The steep angular peaks of the Brooks Range are largely barren, while alpine vegetation can be found at lower eleva¬ tions (Nowacki et al, 2001). Forests and woodlands dominate much of the Kobuk Ridge and Valley ecoregion on the southern flanks of the Brooks Range (Nowacki et al, 2001). The Kotzebue Lowlands lie to the west of the Kobuk Ridge and Valley ecoregion and is dominated by tundra and coastal ecosystems.…”

Section: Study Areamentioning

confidence: 99%

“…The Kotzebue Lowlands lie to the west of the Kobuk Ridge and Valley ecoregion and is dominated by tundra and coastal ecosystems. The Seward Peninsula ecoregion is a mosaic of extensive hills, coastal lowlands and isolated rug¬ ged mountain complexes (Nowacki et al, 2001). The moist polar climate supports tundra, dryas, and shrub communities (Nowacki et al, 2001).…”

Section: Study Areamentioning

confidence: 99%

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Modeling influences on winter distribution of caribou in northwestern Alaska through use of satellite telemetry

Joly

2011

Ran

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I hypothesize that the distribution of barren-ground caribou (Rangifer tarandus granti) is affected by multiple, interrelated factors. These factors include, but are not limited to, terrain and snow characteristics as well as predation pressure and habitat. To test this hypothesis, I attributed caribou locations derived from satellite telemetry over a 6 year period with terrain (elevation, slope, aspect, and ruggedness), habitat characteristics, and moose density -potentially an index of wolf predation pressure. These locations were compared to random locations, attributed using the same data layers, using logistic regression techniques to develop resource selection functions (RSFs). I found that caribou moved significantly less during mid-winter than early-or late-winter and that cows moved significantly more in April than bulls due to their earlier departure on their spring migration. Distribution was different between cows and bulls. Terrain variables were important factors but were scale-dependent. Cows avoided forested areas, highlighting the importance of tundra habitats, and selected for dwarf shrub, with relatively high lichen cover, and sedge habitat types. Bulls selected for dryas, coniferous forest and dwarf shrub habitats but against lowland sedge, upland shrub and burned tundra. Cow distribution was negatively correlated with moose density at the scale of the Seward Peninsula. My results support the hypothesis that caribou distribution during winter in northwest Alaska is affected by multiple, interrelated factors. These results may be useful for researchers to track and/or model changes in future patterns of range use over winter.

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Section: Study Areamentioning

confidence: 99%

Section: Study Areamentioning

confidence: 99%

Section: Study Areamentioning

confidence: 99%

Section: Study Areamentioning

confidence: 99%

Section: Study Areamentioning

confidence: 99%

See 3 more Smart Citations

Modeling influences on winter distribution of caribou in northwestern Alaska through use of satellite telemetry

Joly

2011

Ran

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Using dissolved organic matter age and composition to detect permafrost thaw in boreal watersheds of interior Alaska

et al. 2014

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Recent warming at high latitudes has accelerated permafrost thaw, which can modify soil carbon dynamics and watershed hydrology. The flux and composition of dissolved organic matter (DOM) from soils to rivers are sensitive to permafrost configuration and its impact on subsurface hydrology and groundwater discharge. Here, we evaluate the utility of DOM composition and age as a tool for detecting permafrost thaw in three rivers (Beaver, Birch, and Hess Creeks) within the discontinuous permafrost zone of interior Alaska. We observed strong temporal controls on Δ14C content of hydrophobic acid isolates (Δ14C‐HPOA) across all rivers, with the most enriched values occurring during spring snowmelt (75 ± 8‰) and most depleted during winter flow (−21 ± 8‰). Radiocarbon ages of winter flow samples ranged from 35 to 445 yr BP, closely tracking estimated median base flow travel times for this region (335 years). During spring snowmelt, young DOM was composed of highly aromatic, high molecular‐weight compounds, whereas older DOM of winter flow had lower aromaticity and molecular weight. We observed a significant correlation between Δ14C‐HPOA and UV absorbance coefficient at 254 nm (α254) across all study rivers. Using α254 as an optical indicator for Δ14C‐HPOA, we also observed a long‐term decline in α254 during maximum annual thaw depth over the last decade at the Hess Creek study site. These findings suggest a shift in watershed hydrology associated with increasing active layer thickness. Further development of DOM optical indicators may serve as a novel and inexpensive tool for detecting permafrost degradation in northern watersheds.

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Soil surface organic layers in Arctic Alaska: Spatial distribution, rates of formation, and microclimatic effects

et al. 2015

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Organic layers of living and dead vegetation cover the ground surface in many permafrost landscapes and play important roles in ecosystem processes. These soil surface organic layers (SSOLs) store large amounts of carbon and buffer the underlying permafrost and its contained carbon from changes in aboveground climate. Understanding the dynamics of SSOLs is a prerequisite for predicting how permafrost and carbon stocks will respond to warming climate. Here we ask three questions about SSOLs in a representative area of the Arctic Foothills region of northern Alaska: (1) What environmental factors control the thickness of SSOLs and the carbon they store? (2) How long do SSOLs take to develop on newly stabilized point bars? (3) How do SSOLs affect temperature in the underlying ground? Results show that SSOL thickness and distribution correlate with elevation, drainage area, vegetation productivity, and incoming solar radiation. A multiple regression model based on these correlations can simulate spatial distribution of SSOLs and estimate the organic carbon stored there. SSOLs develop within a few decades after a new, sandy, geomorphic surface stabilizes but require 500-700 years to reach steady state thickness. Mature SSOLs lower the growing season temperature and mean annual temperature of the underlying mineral soil by 8 and 3°C, respectively. We suggest that the proximate effects of warming climate on permafrost landscapes now covered by SSOLs will occur indirectly via climate's effects on the frequency, extent, and severity of disturbances like fires and landslides that disrupt the SSOLs and interfere with their protection of the underlying permafrost.

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Unified Ecoregions of Alaska: 2001

Cited by 88 publications

References 0 publications

Modeling influences on winter distribution of caribou in northwestern Alaska through use of satellite telemetry

Modeling influences on winter distribution of caribou in northwestern Alaska through use of satellite telemetry

Using dissolved organic matter age and composition to detect permafrost thaw in boreal watersheds of interior Alaska

Soil surface organic layers in Arctic Alaska: Spatial distribution, rates of formation, and microclimatic effects

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