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Septoria canker remains the most important disease of poplars in intensively managed forest plantations. Genetic resistance has long been considered the best way to manage for this disease. Transgenic resistance mediated by RNA silencing against pathogens and pests (HIGS: host-induced gene silencing) has shown promise in other pathosystems but has...
This capstone study reports on global warming-induced changes to the Colorado subalpine zone climate and disturbance regimes. It assesses the impacts of these changes upon the dominant subalpine tree species and summarizes future species distribution modeling for these and other nearby species potentially suitable for the future subalpine zone in...
Rhizopus microsporus is a globally ubiquitous opportunistic human and plant pathogen that is known to harbor endosymbiotic bacteria. Differences between populations of clinical and environmental R. microsporus isolates have yet to be assessed on a global scale. Whole-genome sequence data were used to explore fungal biology and to assess potential...
Anthropogenic induced climate change is predicted to alter distribution of existing plant populations. As plants migrate over space and time, populations often fragment and contract, affecting basic elements of population dynamics (e.g., population size, gene flow, genetic diversity, etc.). Little is known, however, how these impacts on plant species will...
The effects of fire on above-ground forest systems have been extensively studied. However, research on fire effects on belowground processes is lacking. While the soil microbiome is understood to be vital to conifer growth and regeneration, the complexity of soils means that research on the topic has largely been accomplished...
Rhizopogon salebrosus is an abundant ectomycorrhizal fungus common throughout Western North America that forms mutualistic partnerships with Pinus species. Studied for its systematics, use in sapling nurseries, post-fire seedling establishment, and unique evolutionary history, R. salebrosus holds many secrets within its genome. This thesis aims to characterize the mating system,...
Over the last 150 years, Oregon white oak habitat in the Willamette Valley has been converted to support grass crops, orchards and vineyards, cities, and conifer forests, nearly extirpating it from the Willamette Valley. Yet Oregon white oak offers many ecosystem services to the Willamette Valley and its residents. Recent...
Within the Pacific Northwest, USA, root diseases of conifers are a major forest health concern. These diseases are primarily caused by basidiomycete fungi. These fungal associates play a vital role in carbon sequestration but also have a significant negative economic impact within the timber industry. As a result, research on...
In recent decades the habitat of North American beaver (Castor canadensis) has expanded from boreal forests into pan-Arctic tundra ecosystems. It is unknown how the advance of beavers into Arctic watersheds will impact microbial communities responsible for the mineralization of organic matter (OM), which has implications for carbon cycling. To...
Managers of forest and plantation ecosystems are encountering growing problems involving plant pathogens and the expanding geographic ranges of these pathogens. Historically unexposed stands are exceptionally vulnerable when a non-native pathogen is introduced because these pathogens can cause devastating disease in a host population that lacks co-evolved resistance mechanisms. One...
Intensifications in seasonal temperature variation, attributed to increased greenhouse gas concentrations, are having an adverse effect on the forest composition of the northeastern United States. New York’s temperate broadleaf forests are undergoing alterations including a decline of the native sugar maple (Acer saccharum), as the species’ population begins to decrease...
Improving crop cultivars for use on organic farms is pertinent, as current elite germplasm is less resilient within the more variable context of organic farm environments. Although a growing number of studies have focused on organic plant breeding in cereal crops, very few have focused on vegetable crops, especially those...
Floodplains are a significant and increasingly threatened ecosystem. As restoration projects are implemented more frequently in degraded floodplains, novel methods are emerging with a focus on restoring critical processes in which vegetation plays a key role. The purpose of this paper is two-fold: 1) to develop expectations for vegetation response,...
Treated wood commodities disposed of in landfills contain chemicals that can migrate into the environment. Wood treatments such as ammoniacal copper zinc arsenate (ACZA) contain heavy metals which prevent the biological degradation of wood. These metals can migrate out of treated wood into soil or groundwater, posing environmental hazards. This...
Sudden oak death is caused by the clonally reproducing generalist oomycete Phytophthora ramorum. The pathogen can infect more than 130 different plant hosts including Quercus spp., Larix kaempferi, and Notholithocarpus densiflorus, as well as common nursery genera such as Rhododendron and Camelia, where it causes symptoms ranging from bleeding cankers...
Increased atmospheric carbon emissions of carbon monoxide, carbon dioxide, and methane acerbate climate change through carbon cycle disruption. Riparian areas offer substantial ecosystem services such as water filtration, slowing and cooling, and as is being discovered, a significant carbon sink. Total percent carbon and carbon stocks in restored riparian areas...
An increase in frequency and severity of hot, dry summers has been associated with a dramatic shift in the coniferous forests of western Oregon’s valleys, especially on the privately-owned properties along the low-elevation edges of these valleys. Various conifer species, including Douglas-fir (Pseudotsuga menziesii), are declining in these forests, leaving...
Arbuscular mycorrhizal fungi (AMF) are plant symbionts that associate with the vast majority of terrestrial plants species. The AMF colonizes the plant roots by penetrating the root cortical cells, where the fungi exchanges mineral nutrients with the host plant for photosynthates. This association exists as a complex system in which...
The climate of the Pacific Northwest is in flux, and existing forest ecosystems are stressed and poised to shift in fundamental ways, with or without human intervention. This dissertation probes the nature of forest responses to environmental change through investigations of morphology and genetics of three species of alder co-occurring...