Fire is the dominant disturbance process in western U.S. forests, and although effects of fire in upland forests are relatively well-studied, there is little information about fire effects on riparian forests, critical areas of the landscape for both habitat and water quality. This dissertation examines different aspects of fire effects...
Pinyon-juniper woodlands throughout the western U.S. have expanded rapidly following European settlement during the late 19th century. In central and eastern Oregon, western juniper (Juniperus occidentalis var. occidentalis Hook.) encroachment has been previously documented in the sagebrush steppe and upper elevation aspen communities. While these vegetation changes and dynamics have...
Small broomrape (Orobanche minor) is an obligate, chlorophyll-lacking parasite that parasitizes red clover (Trifolium pratense) roots. This study was conducted to develop and implement an integrated, biologically based control program for small broomrape by using wheat as a false host to reduce the soil seed bank. The relationship between temperature...
Disturbance and microclimate interact to play a central role influencing the composition and structure of plant communities. In this thesis, I examined plant community composition and structure twenty years after high severity wildfires with and without post-fire management (salvage logging, fuel treatment, tree planting, and shrub release) under contrasting microclimatic...
A fossil-calibrated phylogenetic framework based on exemplars from each of the four taxonomic sections within Pinus was created using multiple nuclear and chloroplast loci. Calibration at the well-defined subgeneric split within Pinus with either fossil leaves and cones (ca. 45 million years ago) or fossil wood (ca. 85 million years...
Fire suppression in the last several decades has resulted in unprecedented accumulations of organic matter on the landscape, leading to an increase in large, intense wildfires. This study investigated the soil microbial community (using phospholipid fatty acid analysis) across recently burned forests on the eastern slope of the Cascade Range...
Juniper is a native species to Oregon and confers ecological benefits to wildlife when it is at savannah and transitional densities. Its range and extent have fluctuated with climatic change, but the current range expansion is unprecedented in its extent. The range expansion has been associated with the degradation of...
Weeping alkaligrass (Puccinellia distans) and Nuttall’s alkaligrass (Puccinellia
nuttalliana) infest Kentucky bluegrass seed fields of eastern Oregon. Weeping
alkaligrass is an introduced species from Eurasia, whereas Nuttall’s alkaligrass is
native to semi arid environments of western North America. These species are often
referred to collectively as ‘alkaligrass’; however, for farmers...
The effects of fire severity on post-fire succession and shrub demography were quantified in shrub-steppe grasslands and subalpine forests in the Hells Canyon of the Payette National Forest, Idaho. Following the 1988 Eagle Bar Fire, species frequency, community diversity, fire adaptations, and stand ages were quantified at 12 plots in...
The use of Native American fire regimes evolved in the Klamath-Siskiyou bioregion over millennia. A mixture of Native American and Euro-American socio-cultural management has developed from adaptations to climate, topography, ecological processes, and land use practices. This research incorporates Traditional Ecological Knowledge (TEK) to partially examine the role of tribal...