Treesearch

Heating of unburned fuel by attached flames and plume of a wildfire can produce high spread rates that have resulted in firefighter fatalities worldwide. Qualitative flow fields of the plume of a gas burner embedded in a table tilted to 0°, 10°, 20°, and 30° above horizontal were imaged using the retroreflective shadowgraph technique as a means to understand plume attachment and related behavior. Tilting of the plume in the uphill direction for all non-zero slopes was explained by an imbalance in the flow of air entrained into the plume. Reversal in direction of fluid flow uphill from the...

Fire-prone landscapes present many challenges for both managers and policy makers in developing adaptive behaviors and institutions. We used a coupled human and natural systems framework and an agent-based landscape model to examine how alternative management scenarios affect fire and ecosystem services metrics in a fire-prone multiownership landscape in the eastern Cascades of Oregon. Our model incorporated existing models of vegetation succession and fire spread and information from original empirical studies of landowner decision making. Our findings indicate that alternative management...

Grassland and shrub-steppe ecosystems are increasingly threatened by anthropogenic activities. Loss of native habitats may negatively impact important small mammal prey species. Little information, however, is available on the impact of habitat variability on density of small mammal prey species at broad spatial scales. We examined the relationship between small mammal density and remotely-sensed environmental covariates in shrub-steppe and grassland ecosystems in Wyoming, USA. We sampled four sciurid and leporid species groups using line transect methods, and used hierarchical distance-sam...

Invasive hybridization, in which an introduced species may introgressively hybridize with a native taxon and threaten its persistence, is prominently featured in the conservation literature. One of the most frequently cited examples of this phenomenon involves interactions between native westslope cutthroat trout Oncorhynchus clarkii lewisi and introduced rainbow trout Oncorhynchus mykiss in a portion of the U.S. Northern Rocky Mountains (Allendorf & Leary, 1988). A recent paper by Muhlfeld et al. (2017) revisited this issue and concluded that introgressive hybridization between these taxa...

PREMISE OF THE STUDY: With ongoing climate change, understanding of intraspecific adaptive variation is critical for conservation and restoration of plant species. Such information is especially scarce for threatened and endangered tree species, such as Pinus albicaulis Engelm. Therefore, our principal aims were to assess adaptive variation and characterize its relationship with climate of seed origin. METHODS: We grew seedlings from 49 P. albicaulis populations representative of the interior northwestern United States in two common garden fi eld experiments under warm-dry conditions that...

Winter recreation is a rapidly growing activity, and advances in technology make it possible for increasing numbers of people to access remote backcountry terrain. Increased winter recreation may lead to more frequent conflict between recreationists, as well as greater potential disturbance to wildlife. To better understand the environmental characteristics favored by winter recreationists, and thus predict areas of potential conflict or disturbance, we modeled terrain selection of motorized and non-motorized recreationists, including snowmobile, backcountry ski, and snowmobile-assisted...

Smoke can manifest itself as a towering plume rising against the clear blue sky-or as a vast swath of thick haze, with fingers that settle into valleys overnight. It comes in many forms and colors, from fluffy and white to thick and black. Smoke plumes can rise high into the atmosphere and travel great distances across oceans and continents. Or smoke can remain close to the ground and follow finescale topographical features.

Seed production is an essential component of postdisturbance recovery for mountain big sagebrush (Artemisia tridentata Nutt. ssp vaseyana [Rydb] Beetle; MBS). We tested a method for rapid estimation of MBS seed production using measurements of inflorescence morphology. We measured total stem length, stem length from first branchlet to stem tip, stem diameter, fresh weight, and number of stem branchlets for 750 inflorescences collected from five central and southern Utah sites. Florets per inflorescence were counted to provide an estimate of seed production potential. We used regression...

Wildfires in the Great Basin have resulted in widespread loss of Wyoming big sagebrush (Artemisia tridentata Nutt. ssp. wyomingensis Beetle & Young), an ecologically important shrub that has proven difficult to establish from seed.We sought to identify optimal seeding practices forWyoming big sagebrush in the context of postfire seeding operations involving rangeland drills. In an experiment replicated at three burned sites in the northern Great Basin, we compared Wyoming big sagebrush establishment across treatments differing by seed delivery technique, timing, and rate of seed application...

The winter annual grass Bromus tectorum (cheatgrass) has become highly invasive in semiarid ecosystems of western North America. In these areas, a natural phenomenon, complete cheatgrass stand failure (‘die-off’), is apparently caused by a complex interaction among soilborne fungal pathogens. Several Fusarium strains belonging to the Fusarium tricinctum species complex were isolated from these soils and found to be pathogenic on B. tectorum seeds. One of these strains was produced in cheatgrass seed culture to evaluate its ability to produce phytotoxins. Six metabolites were isolated and...