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Graduate Research Publications


A Spatiotemporal Mountain Pine Beetle Outbreak Model Predicting Severity, Cycle Perior, and Invasion Speed

By: Jacob P. Duncan
P.H.D. Dissertation

Abstract

The mountain pine beetle (MPB, Dendroctonus ponderosae), a tree-killing bark beetle, has historically been part of the normal disturbance regime in lodgepole pine (Pinus contorta) forests. In recent years, warm winters and summers have allowed MPB populations to achieve synchronous emergence and successful attacks, resulting in widespread population outbreaks and resultant tree mortality across western North America. We develop an age-structured forest demographic model that incorporates temperature-dependent MPB infestations: the Susceptible-Infested-Juvenile (SIJ) model. Stability of fixed points is analyzed as a function of population growth rates, and indicates the existence of periodic outbreaks that intensify as growth rates increase. We devise analytical methods to predict outbreak severity and duration as well as outbreak return time... Download


The Demography and Determinants of Population Growth in Utah Moose (Alces allces shirasi)

By: Joel S. Ruprecht
M.S. Thesis

Abstract

Moose in Utah represent the southernmost naturally occurring populations of moose in the world. Concerns over possible numeric declines and a paucity of baseline data on moose in the state prompted the Utah Division of Wildlife Resources to initiate a study of moose demography in collaboration with Utah State University. The objectives of this study were to 1) determine reproductive rates of moose in Utah and the factors which influence them, and 2) combine aerial count data from multiple management units within the state to identify factors which influence interannual variation in population growth rates... Download


Cultural, Comparing Conventional and Noninvasive Monitoring Techniques for Assessing Cougar Population Size in the Southern Greater Yellowstone Ecosystem

By: Peter D. Alexander
M.S. Thesis

Abstract

Cougars (Puma concolor) are difficult to census due to their large home ranges, low densities, and cryptic nature. The conventional “gold-standard” method for estimating cougar abundance entails the capture and radio-tagging of individuals in a study area in an attempt to acquire a direct enumeration of animals in the population. While this method provides an accurate abundance estimate, it is logistically challenging and prohibitively expensive. Noninvasive survey techniques may offer the ability to both accurately and inexpensively monitor cougar populations. While noninvasive techniques have been used on cougar populations, there remain questions on their accuracy and comparative efficacy. We estimated the density of a cougar population in Northwest Wyoming using direct enumeration, and used this estimate as a reference with which to evaluate the accuracy and cost-effectiveness of three types of noninvasive surveys performed between 2010 and 2014. The noninvasive methods included two annual mark- recapture sessions of: 1) remote camera trapping, 2) winter hair-collection transects, and 3) scat detection dog surveys... Download