Browsing by Author "Challender, Stuart"

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Data from: An exploration for truth in soil parent materials in Hyalite Canyon, Montana [dataset]
(2015-08) Sugden, John Charles; Ewing, Stephanie A.; Challender, Stuart; Hartshorn, Anthony
The raw data set contains geochemical data from a soil "lithosequence" in Hyalite Canyon, MT near the Langohr Campground and includes data for underlying rock. Data for many major and minor (including rare earth and high field strength) elements and oxides are included. Atmospheric deposition samples were collected at the Arthur Post Farm and from the rooftops of Bobcat Stadium. Duplicates included in the data set are marked. The three calculation spreadsheets convey methods to calculate the fractional rock influence on soil materials <2mm; to determine chemical depletion from rock only and from rock and atmospheric deposition; and to calculate mass balance using rock only, atmospheric deposition only, and mass balance using both rock and atmospheric deposition scaled using the fraction rock calculations mentioned above.
Summer range occupancy modeling of non-native mountain goats in the greater Yellowstone area
(2015-11) DeVoe, Jesse D.; Garrott, Robert A.; Rotella, Jay J.; Challender, Stuart; White, Patrick J.; O'Reilly, Megan; Butler, Carson J.
Non-native species can have adverse impacts on native species. Predicting the potential extent of distributional expansion and abundance of an invading non-native species can inform appropriate conservation and management actions. Non-native mountain goats (Oreamnos americanus) in the greater Yellowstone area (GYA) have substantial potential to occupy similar habitats to native Rocky Mountain bighorn sheep (Ovis canadensis canadensis). To understand the potential for expansion of mountain goats in the GYA, this study evaluated detection-nondetection data derived from ground-based occupancy surveys of viewsheds partitioned into a grid of 100 × 100 m sampling units. Surveys were conducted over three summer seasons (2011–2013) in two study areas with well-established mountain goat populations. Relationships between scale-specific habitat covariates and mountain goat selection were evaluated to model occupancy and detection probabilities based on mountain goat detections in 505 of the 53,098 sampling units surveyed. Habitat selection was most strongly associated with terrain covariates, including mean slope and slope variance, at a spatial scale of 500 × 500 m, and canopy cover, heat load, and normalized difference vegetation index at a spatial scale of 100 × 100 m. These results provide new insight into multi-scale patterns of mountain goat habitat selection, as well as evidence that mean slope and slope variance are more informative terrain covariates than distance to escape terrain, which has been commonly used in published mountain goat habitat models. The model predicted 9,035 km2 of suitable habitat within the GYA, of which 57% is currently un-colonized. Seventy-five percent of all bighorn observations recorded in the GYA fall within predicted suitable mountain goat habitat. We also estimated that the GYA might have the potential to support 5,331–8,854 mountain goats when all predicted habitat is occupied, or approximately 2.5–4.2 times the most recent abundance estimate of 2,354.
Using time lapse photography to document terrain preferences of backcountry skiers
(2020-04) Saly, Diana; Hendrikx, Jordy; Birkeland, Karl W.; Challender, Stuart; Johnson, Jerry
Travel in avalanche terrain requires considered and careful selection of appropriate terrain to reduce exposure to avalanche danger. In many parts of the world, recreational backcountry skiers in avalanche terrain are aided by a regional avalanche forecast. The overall aim of an avalanche forecast is for users to adjust their terrain choices in response to the avalanche danger rating and avalanche problem, thereby reducing their risk of an avalanche involvement. In this paper we present a novel passive observation technique to assess how lift assisted backcountry skiers adjust their terrain use in response to the avalanche danger rating. This paper develops and demonstrates a method to record the terrain metrics of all skiers on an avalanche-prone backcountry slope. Using a remote time-lapse camera focused on a high skier-use backcountry slope, we anonymously recorded the descent route of skiers in ten-second increments. Using 31,966 images over 13 days and 7499 skier point locations, skier locations were digitized from the images, then transformed onto a geo-referenced digital elevation model (DEM) such that terrain metrics could be extracted for each anonymous skier location. When these location points are compared to simultaneous GPS measurements, the horizontal accuracy was estimated to be within a 49-m horizontal accuracy, with a 95% confidence interval. Analysis of the terrain metrics for each skier point compared slope, profile curvature (downslope), and plan curvature (cross slope) over days with different forecasted avalanche danger ratings. This statistical analysis was qualitatively supported by a review of the spatial patterns of the terrain choices on these days. Furthermore, we used this technique to estimate group size, and found a surprising number of solo skiers, even on Considerable avalanche danger days. By remotely photographing all skiers on a slope, the data collected provides a large and diverse data set of the terrain preferences of backcountry skiers under varying avalanche conditions, with limited bias. These results have implications for avalanche education by enhancing our understanding of specific terrain management skills by backcountry skiers.