Publications

ContextInteractions among disturbances, climate, and vegetation influence landscape patterns and ecosystem processes. Climate changes, exotic invasions, beetle outbreaks, altered fire regimes, and human activities may interact to produce landscapes that appear and function beyond historical analogs.ObjectivesWe used the mechanistic ecosystem-fire process model FireBGCv2 to model interactions of wi

We developed an automated approach for mapping persistent ice and snow cover (glaciers and perennial snowfields) from Landsat TM and ETM+ data across a variety of topography, glacier types, and climatic conditions at high latitudes (above ~65°N). Our approach exploits all available Landsat scenes acquired during the late summer (1 August–15 September) over a multi-year period and employs an automa

Avian keratin disorder (AKD), characterized by debilitating overgrowth of the avian beak, was first documented in black-capped chickadees (Poecile atricapillus) in Alaska. Subsequently, similar deformities have appeared in numerous species across continents. Despite the widespread distribution of this emerging pathology, the cause of AKD remains elusive. As a result, it is unknown whether suspecte

Rocky intertidal communities are structured by local environmental drivers, which can be dynamic, fluctuating on various temporal scales, or static and not greatly varying across years. We examined the role of six static drivers (distance to freshwater, tidewater glacial presence, wave exposure, fetch, beach slope, and substrate composition) on intertidal community structure across the northern Gu

In the Arctic Ocean’s southern Beaufort Sea (SB), the length of the sea ice melt season (i.e., period between the onset of sea ice break-up in summer and freeze-up in fall) has increased substantially since the late 1990s. Historically, polar bears (Ursus maritimus) of the SB have mostly remained on the sea ice year-round (except for those that came ashore to den), but recent changes in the extent

State-space models offer researchers an objective approach to modeling complex animal location data sets, and state-space model behavior classifications are often assumed to have a link to animal behavior. In this study, we evaluated the behavioral classification accuracy of a Bayesian state-space model in Pacific walruses using Argos satellite tags with sensors to detect animal behavior in real t

This five-day field trip visits the most significant mineral deposits in northern southeast Alaska. The trip begins and ends with regional transects in the interior Intermontane terranes around Whitehorse, Yukon, and the Insular terranes along the northern Chatham Strait region of southeast Alaska (Fig. A-1 and Fig. A-2; Plate-1). To put the deposits in a regional tectonic framework, the guidebook

Small solar-powered satellite transmitters and GPS data loggers enable continuous, multi-year, and global tracking of birds. What is lacking, however, are reliable methods to attach these tracking devices to small migratory birds so that (1) flight performance is not impacted and (2) tags are retained during periods of substantial mass change associated with long-distance migration. We developed a

Cryptic nest sites and secretive breeding behavior make population estimates and monitoring of Marbled Murrelets Brachyramphus marmoratus difficult and expensive. Standard audio-visual and radar protocols have been refined but require intensive field time by trained personnel. We examined the detection range of automated sound recorders (Song Meters; Wildlife Acoustics Inc.) and the reliability of

We found that average cytochrome P4501A induction (as measured by EROD activity) during March 2014 was not elevated in wintering harlequin ducks captured in areas of Prince William Sound oiled by the 1989 Exxon Valdez oil spill, relative to those captured in unoiled areas. This result is consistent with findings from March 2013. We interpret these findings to indicate that exposure of harlequin du

Nearshore marine habitats, which represent the interface among air, land and sea, form a critical component of the Gulf of Alaska (GOA) ecosystem. As an interface, the nearshore facilitates transfer of water, nutrients and biota between terrestrial and oceanic systems, creating zones of high productivity. The nearshore provides a variety of ecosystem services, including (1) nursery grounds for a w

Lakes are prevalent in the Arctic and thus play a key role in regional hydrology. Since many Arctic lakes are shallow and ice grows thick (historically 2-m or greater), seasonal ice commonly freezes to the lake bed (bedfast ice) by winter's end. Bedfast ice fundamentally alters lake energy balance and melt-out processes compared to deeper lakes that exceed the maximum ice thickness (floating ice)