The annual cycles of human- and lightning-caused fires create distinct patterns in time and space. Evaluating these patterns reveals intimate relationships between climate, culture, and ecoregions. I used unique graphical visualization techniques to examine a dataset of 516,691 records of human- and lightning-caused fire-start data from the western United States for the 20-year period 1992-2011. Human-caused fires were ignited throughout the year and near human populations, while lightning-caused fires were confined almost exclusively to the summer and were concentrated in less-populated areas. I utilize graphs and maps to demonstrate the benefit of a longer time frame in strengthening the findings and describing the underlying interactions among climate, society, and biogeography. / 2016-01-14

The popular image of the West in the nineteenth and early twentieth centuries incorporates radically opposing images: the West is viewed as a Garden of Eden at times, but it is also frequently seen as violent, a land inimical to man. The region both attracted and repelled. Among those attracted were artists who carried back some of the first images of the land. Thomas Moran (1837-1926) became associated quite early with the West because a pair of his paintings of western canyons was purchased by the United States Government.

Distichlis stricts as indicated by the available literature is rather unpalatable, but has the ability to grow vigorously on wet, saline, or alkali soils where more palatable species will not survive. D. stricts can be eradicated quickly where drainage and cultivation can be practices, but there are thousands of acres in the United States, Canada, Mexico, and Argentina where cultivation or drainage are impractical or impossible.

Service-grazing is a novel term for grazing done on land not owned or rented by a livestock producer or manager, for the purpose of land management, and for which the owner or land manager receiving grazing services pays compensation to the service provider. This research project seeks to gather detailed information about producers in the Western United States, providing grazing services under this project’s definition of “service-grazing”, with a focus on those operating in California, in order to discover the business models or practices necessary to be successful within a service-based grazing operation. To this end, an online survey consisting of 59 questions was designed and administered to 25 service-grazers operating with the Western United States. Demographic data collected suggested that service-grazers tend to be younger than most sheep producers. They are also highly educated and generally not generational farmers. The majority of service grazers graze mostly goats and are highly dependent on off-farm income. Due to the limited number of responses received to the survey, it is recommended that future work be split into two parts: 1) compiling an accurate and up-to-date list of producers providing grazing services, with detailed demographic information and specific characteristics of each operation; 2) a further survey to question those producers as to the feasibility of transitioning, in whole or in part, from a production-based livestock operation to one providing grazing services.

Dendroclimatologists often approach field work with the intent of reconstructing a particular climate variable (e.g. temperature, streamflow, precipitation). Although guidelines exist for species and site selection, isolating the signal of interest is difficult in areas with complex terrain or a lack of ideal sites. In this case study, I suggest climatological techniques for a more efficient sampling scheme and apply these techniques to identify criteria for selecting sites sensitive to winter precipitation in the north-central Rocky Mountains. These techniques include examining factors influencing the regional response of tree growth to climate by utilizing the International Tree-Ring Databank (ITRDB), using eigenvector analyses to identify modes of variability between sites, and delineating climate regions based on the variable of interest through climate regionalization. Results suggest that low- or mid-elevation Pseudotsuga menziesii sites should be targeted for maximizing the winter precipitation signal in the case study area. The season of precipitation impacting growth was found to be a major component of the overall variability between sites.

Range Rider Programs (RRPs) are one example of a proactive non-lethal tool that has been implemented in western United States to mitigate gray wolf (Canis lupus) and livestock conflicts. Because RRPs are an emerging non-lethal tool that little is known about, I selected a qualitative research approach to examine participant perceptions to further contemporary understanding of how these efforts are implemented and potential benefits. I surveyed 51 participants from 17 Range Rider Programs (RRPs) in Montana, Washington, and Oregon to determine participant perceptions regarding effectiveness of RRPs as a non-lethal approach to mitigate wolf-conflicts. I developed a RRPs typology based on information provided by the participants interviewed. The typology identified 3 versions of RRPs programs that revolved around the role of the range rider. These roles included: 1) livestock monitoring, 2) wolf surveillance, and 3) livestock herding. The RRPs, although diverse in operations, shared traits exemplified by community-based conservation programs. Interview responses suggested a RRP’s primary contribution may not be a direct reduction in livestock depredation by wolves, but instead a collection of indirect technical and socio-political benefits. To improve current RRPs and develop future efforts, programs should be realistic in expectations and the sponsors must work closely with rancher participants to develop an adaptive program that meets their needs, maintains transparent and frequent communication, and provides a forum for feedback.

Flood frequency analysis over the western United States is complicated by annual peak flow records that frequently contain annual flows generated from distinctly different flood generating mechanisms. Bulletin17B (B17B) and its update Bulletin 17C (B17C) recognized the difficulties in determining flood frequency estimates with streamflow records that contain a mixed population of flood generated peaks, and recommend developing separate frequency curves when the hydrometeorologic mechanisms that generated the annual peak flows can be separated into distinct populations. Yet challenges arise when trying to consistently quantify the physical process that generated the observed flows. This thesis examines the role played by different flood producing mechanisms in generating annual maximum floods throughout the western United States using process-driven mixed populations. First I evaluate the impacts of hydrometeorological processes on flood frequency in the western United States, with emphasis on the spatial and fractional contributions of atmospheric rivers (ARs) and eastern North Pacific tropical cyclones and their remnants (TC events) on annual maximum flows throughout this area. Six main areas in which flooding are impacted by ARs at varying degrees are found throughout the western United States. The Pacific Northwest and the northern California coast have the highest fraction of AR-generated peaks (~80–100%), while eastern Montana, Wyoming, Utah, Colorado, and New Mexico have nearly no impacts from ARs. The individual regions of the central Columbia River Basin in the Pacific Northwest, the Sierra Nevada, the central and southern California coast, and central Arizona all show a mixture of 30–70% AR-generated flood peaks. Analyses related to the largest flood peaks on record highlight the strong impact of ARs on flood hydrology in this region. Conversely, TC events play a limited role in controlling the upper tail of the flood peak distributions across the western United States. Southern California, Arizona, southernmost Nevada and Utah, southern and western New Mexico, central Colorado, and Texas have the highest fractional contributions of TC-event-generated annual maximums flows (~5-14%). I then build on these insights to develop a statistical framework to perform a process-driven flood frequency analysis using the AR/non-AR-generated annual peak flows identified at 43 long-term U.S. Geological Survey (USGS) streamgages in the western United States. I use a simulation framework to perform flood frequency analyses in terms of mixed distributions and quantify the corresponding uncertainties by accounting for mixed populations. Sites with notably different quantile estimates in the upper tail of the distribution between the single (homogeneous) and the weighted (heterogeneous) population methodologies are found when (i) potentially influential low floods (PILFS) are identified and/or (ii) when the composite distribution contains markedly different at-site log-unit skews (shape parameter) among the AR/non-AR subpopulations compared to the single homogeneous population.

abstract: Many previous investigators highlight the importance of snowfall to the water supply of the western United States (US). Consequently, the variability of snowpack, snowmelt, and snowfall has been studied extensively. Snow level (the elevation that rainfall transitions to snowfall) directly influences the spatial extent of snowfall and has received little attention in the climate literature. In this study, the relationships between snow level and El Niño-Southern Oscillation (ENSO) as well as Pacific Decadal Oscillation (PDO) are established. The contributions of ENSO/PDO to observed multi-decadal trends are analyzed for the last ~80 years. Snowfall elevations are quantified using three methods: (1) empirically, based on precipitation type from weather stations at a range of elevations; (2) theoretically, from wet-bulb zero heights; (3) theoretically, from measures of thickness and temperature. Statistically significant (p < 0.05) results consistent between the three datasets suggest snow levels are highest during El Niño events. This signal is particularly apparent over the coastal regions and the increased snow levels may be a result of frequent maritime flow into the western US during El Niño events. The El Niño signal weakens with distance from the Pacific Ocean and the Southern Rockies display decreased snow level elevations, likely due to maritime air masses within the mid-latitude cyclones following enhanced meridional flow transitioning to continental air masses. The modulation of these results by PDO suggest that this El Niño signal is amplified (dampened) during the cold (warm) phase of the PDO particularly over Southern California. Additionally, over the coastal states, the La Niña signal during the cold PDO is similar to the general El Niño signal. This PDO signal is likely due to more zonal (meridional) flow throughout winter during the cold (warm) PDO from the weakening (strengthening) of the Aleutian low in the North Pacific. Significant trend results indicate widespread increases in snow level across the western US. These trends span changes in PDO phase and trends with ENSO/PDO variability removed are significantly positive. These results suggest that the wide spread increases in snow level are not well explained by these sea surface temperature oscillations. / Dissertation/Thesis / Ph.D. Geography 2011

Geographic Information Systems (GIS) are increasingly used to examine fire activity. This study uses GIS to determine fire likelihood probabilities at an intermediate scale ( I-kilometer) on a daily basis given readily available data. Layers used for the analysis included slope, aspect, elevation, fuel type, proximity to existing fires, maximum temperature, minimum temperature, relative humidity, average vapor pressure deficit, precipitation, 1-hour fuel moisture, and 10-hour fuel moisture. There were three objectives of this study: 1. Establish a correlation between burn perimeters and readily available topographic and environmental data, and map the spatial distribution of these as fire likelihood areas; 2. Compare each day's fire likelihood areas to fire perimeters from the next day to determine to what extent areas deemed to be high fire likelihood on a given day could be used to identify likelihood areas for the subsequent day; 3. Create a generalized model using the fewest and most frequent significant variables and test this model as a general predictive tool for fire likelihood over a given season. Redundant variables and variables determined not to be significant at this scale were removed from the model. Variables that best explained the fire activity were identified and used to spatially map fire likelihood for any given day. By comparing subsequent days fire activity to the previous days fire likelihood areas, it was determined that the previous fire likelihood areas can be used as an indication for the subsequent day' s fire likelihood areas with a reasonable level of accuracy. Although factors changed from day to day, the most significant variables tended to be slope, elevation, fuel type, and 1-hour fuel moisture. These variables were incorporated into a generalized model which, when mapped spatially, provided a method to compare increasing or decreasing levels of fire likelihood on a temporal scale. The results were coarser, but still indicated that a generalized model could be used to identify the next day' s fire likelihood areas given the previous days spatial plots. When compared to new fire starts, fires occurred in areas of moderate fire likelihood probabilities and very few occurred in areas of low probability.

Taxonomic delimitation of rare species is vital for accurate assessments of diversity and for their conservation. Cycladenia humilis, the sole species of Cycladenia, is an enigmatic perennial widely dispersed across the western United States. Within this species there are three currently recognized varieties: C. humilis var. humilis in Northern California, C. humilis var. venusta in Southern California, and C. humilis var. jonesii in Utah and Northern Arizona. Some populations occur geographically in areas between the typical distribution of each variety and the presently accepted taxonomy inadequately addresses these populations. Using five nDNA regions, we seek to clarify relationships between current varieties and assess the pattern of variation throughout the species. Analyses including K-means clustering, principle component analysis, fields for recombination, AMOVA, and ecological niche modeling were applied. Results indicate significant genetic structure between varieties and supports recognition of C. jonesii at the species level as distinct from C. humilis. Well defined intraspecific groupings are evident in the data, with evidence supporting the recognition of an additional variety in C. humilis, and two varieties in C. jonesii. Haplotype diversity and relationships between metapopulation clusters inform conservation efforts regarding diversity within Cycladenia and offer insights into the historical demography of this genus.