Questions: Can a statistical model be designed to represent more directly the nature of organismal response to multiple interacting factors? Can multiplicative ernel smoothers be used for this purpose? What advantages does this approach have over more traditional habitat modelling methods?
Methods: Non-parametric multiplicative regression (NPMR)was developed from the premises...
The specificity of quantitative host resistance to plant disease has long been a controversial issue. We examined interactions between wheat (Triticum aestivum) and Mycosphaerella graminicola, causal agent of Septoria tritici blotch, to determine whether specific interactions occur between host and pathogen genotypes that could be involved in eroding quantitatively expressed...
The purpose of this dissertation was to define macrolichen community gradients in relation to succession, grazing and the environment. First, species scores indicating when macrolichen species appeared following disturbance were derived from the literature. Weighted averaging of these data with a community matrix created a successional score for each sample...
More than 4,000 specimens of fruits and seeds were extracted
from the matrix removed from inside the skulls of sabre-tooth cats
excavated from various pits in the Rancho La Brea deposits. Of this
number, spproximately 1,445 specimens are involved in this study.
Many comparisons with modern fruits and seeds made...
The showy biennial to short-lived perennial Oenothera wolfii (Munz) Raven, Dietrich & Stubbe (Wolf’s evening primrose) occurs in only a small number of isolated populations on the southern Oregon and northern California coast. This rare species is currently listed as Threatened in Oregon, and is considered a Species of Concern...
The Pacific Northwest has become one of the nation’s premier sweet cherry,
Prunus avium, production areas. As production of sweet cherries has flourished in
Oregon and Washington, so has powdery mildew, caused by the fungus
Podosphaera clandestina, which infects both foliage and fruit causing severe
economic damage to growers. Sweet...
Published July 1981. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalog
Graphium sp., a eukaryotic alkanotroph, is able to oxidize small-molecular weight gaseous n-alkanes, diethyl ether and the branched ether, methyl tert butyl ether
(MTBE). However, information regarding the biochemistry of fungal-mediated alkane and ether metabolism is limited, and questions regarding the identity of alkane oxidation catalysts and the genetic underpinnings...
Sweet corn (Zea mays L.) yields in the Willamette Valley of Oregon have been declining since the early 1990’s. Studies were done to determine if there is a relationship between ear weight and several disease parameters including necrotic crowns or stalk nodes, nodal root rot, radicle root rot, and sub-crown...
Pollination ecology may play an important role in the maintenance of selfing in populations of self-compatible hermaphroditic plants where both selfing and outcrossing occur (mixed mating). Behavior and abundance of pollinators can influence the two major modes of selfing; autogamy (selfing within a flower) and geitonogamy (selfing between flowers on...
Field trials were conducted during 2001 to 2003 to investigate soil population dynamics of Meloidogyne chitwoodi, tuber symptom suppression using oxamyl, and post-harvest tuber symptom development on short-season potato varieties Russet Norkotah and Russet Nugget (San Luis Valley only). The experiments were located in the San Luis Valley in Colorado,...
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...
The chlamydospore is a survival spore produced by 35 of the 75 described species of Phytophthora. Phytophthora ramorum Werres, de Cock & Man in't Veld, the causal agent of Sudden Oak Death (SOD), produces abundant chlamydospores in artificial culture and plant tissue. The chlamydospore is likely the most important survival...
In ecological restoration, species that are sown to increase the native plant
diversity range in establishment ability. Some species readily establish, while others
rarely do. This study set out to investigate some of the potential processes influencing
species establishment, as well as the traits that are associated with the success...
The septoria diseases of winter wheat are a limiting factor to wheat production in the Willamette Valley. This publication will describe the symptoms and development of the septoria diseases, including the influence of environmental conditions, the reactions of different cultivars to Septoria, the impact of Septoria on yield, and control...
Podosphaera macularis causes one of the most important diseases, powdery mildew, of Humulus lupulus (hop). If left unmanaged, hop powdery mildew can cause total crop loss due to disease or browning of hop cones rendering the cones unmarketable to buyers. The Hop Powdery Mildew Infection Risk Index (HOPS) is heavily...
Decomposing logs in Douglas-fir - western hemlock forests in the Pacific Northwest are systems in which many organisms interact. Fungi in these systems include both mycorrhizal fungi associated with hemlock seedlings and many species of saprotrophic wood decomposer fungi. It is very likely that these two groups of fungi interact...
The main objective of this thesis was to determine the influence of tree vigor on susceptibility to Armillaria root disease. First, the effect of thinning, fertilizing and pruning on tree vigor of four young Douglas-fir (Pseudo tsuga menziesii var. menziesi,) plantations was explored. Tree vigor was calculated by measuring wood...
Disease is often overlooked as a natural disturbance agent in plant communities. This study examines what effects, if any, a disease-mediated disturbance has on the plant community as a whole in old-growth and mature forests of western Oregon. Phellinus weirii (Murrill) Gilbertson (Family: Hymenochaetaceae) is a native root-rotting pathogen that...
In addition to its longstanding recognition as an influential evolutionary process, interspecific hybridization is increasingly regarded as a potential threat to the genetic integrity and survival of rare plant species, manifested through gamete wasting, increased pest and disease pressures, outbreeding depression, competitive exclusion, and genetic assimilation. Alternatively, hybridization has also...
An analysis was made of the recent catastrophic disturbance history of forests at Mount Rainier National Park. Basic data were tree ages from ring counts of increment cores taken from the early seral cohort, field mapping of age class boundaries and aerial photograph interpretation. Maps of present stand ages were...
Although terrestrial lichens and bryophytes are common in upland plant communities of the Blue Mountains in northeast Oregon, research on cryptogam communities in this region is wanting. Studies have shown that lichens and bryophytes can reduce soil erosion and increase soil fertility in other semiarid habitats of North America. Understanding...
The purpose of this study was to determine plant species composition, community structure, successional relationships, vegetational development and plant distributions in estuarine salt marshes on the Pacific Coast of Oregon.
Quadrat and transect samples of plant presence and cover, collected from April 1971 - June 1974, were subjected to phytosociological...
A 22 ha, 1S yeas old, diked permanent pasture in the Salmon River estuary in Lincoln County, Oregon, was chosen for a study to determine the potential for natural salt marsh restoration with dike breaching. Two undiked fragments of relatively undisturbed salt marsh, one at each end of the study...
Wetlands and wet prairies are economically and environmentally valuable ecosystems, but many have been degraded or converted to other uses. As human understanding of wetlands' value has increased, restoration efforts have grown correspondingly. Restoration attempts use a diversity of methods, which often include seeding with native plant species. This thesis...
The sagebrush steppe ecosystem of the northern Great Basin is severely degraded and continues to decline due in large part to the invasive, non-native annual grasses Bromus tectorum L. (cheatgrass) and Taeniatherum caput-medusae (L.) Nevski (medusahead). Restoration of invasive-dominated areas is difficult, but can be enhanced by adding a carbon...
Epiphytic, planktonic and benthic diatom assemblages were investigated in Netarts Bay, Oregon. Samples were collected for a
one-year period from February 1980 to March 1981. A planktonic flora was observed only during periods of offshore enrichment when marine neritic species were abundant and were transported into the bay by tidal...
North America, with over 400 species of Astragalus (Fabaceae), is one of three major centers of diversity, all of which comprise the majority of the nearly 1750 species of Astragalus worldwide. One of the most diverse species, Astragalus lentiginosus of Section Diphysi, is a polymorphic complex of over 40 varieties,...
Coast redwood (Sequoia sempervirens) (D. Don) Endl. is a host for Phytophthora ramorum but it was unclear if the pathogen represents a significant disease risk to this tree species. In this study the susceptibility of coast redwood seedlings and the likelihood of sporulation on redwood were examined. Two methods were...
The role of unusual geologies in plant distribution and form is well-known. Serpentine (ultramafic) soils exert a particularly strong influence on plants, as evidenced by a high level of endemism and the morphological and physiological traits displayed in adaptation to the extraordinary chemistry of these substrates. Adaptation may lead to...
This research examines the community composition of biotic soil crusts at nine sites in central and eastern Oregon, U.S.A. At each site, data were collected in one pair of livestock-grazed and excluded transects. Variables recorded included: cover of biotic soil crusts and vascular plant species, soil surface pH, electrical conductivity,...
Tanoak (Lithocarpus densiflorus), along with some other members of Fagaceae, are susceptible to sudden oak death caused by the oomycete Phytophthora ramorum. Symptoms of the disease include dying crowns, bleeding cankers, and eventually death of infected trees. The cause of mortality is not well understood, but recent research indicates that...
In vitro growth of twelve isolates of Tither spp., the true truffles, was quantified by an agar-melt procedure. All isolates grew
poorly on media commonly used for the culture of mycorrhizal fungi, but responded markedly to the addition of nitrate, as well as other
inorganic ions, to malt and potato-dextrose...
The study of the infra-specific ranks (i.e., subspecies and variety) can be considered
the study of the process of speciation. Astragalus lentiginosus Douglas ex Hooker
(Fabaceae) is the most taxon rich species in the U.S. flora currently including 40
taxonomic varieties. These varieties were described using traditional taxonomic
methods primarily...
An experimental reintroduction was performed to determine the best method to create new populations of the tuberous species Perideridia erythrorhiza, a rare vascular plant endemic to southern Oregon. Only a handful of sites are currently present, and many of these are subject to other land uses such as urban development...
Tall fescue is thought to have co-evolved with the fungal endophyte Acremonium coenophialum to form a mutualistic relationship. Endophyte-infected (EI) plants can have increased growth and survival when compared with endophyte-free (EF) plants. Responses to endophyte-infection vary and are host-genotype and fungal-biotype specific. Mechanism(s) by which endophyte-infection confers increased growth...
The primary goal of this dissertation research was to assess the use of compost for the control of several foliar and soil borne diseases commercially important in the Pacific Northwest. The use of compost teas to control of gray mold (Botrytis cinerea) on geraniums, powdery mildew (Podosphearapannosa var. rosae), rust...
Population dynamics, plant communities, and abiotic environments of three narrowly endemic, allopatric mariposa lilies (Calochortus Pursh) are described and compared. All were restricted to ultramafic soils in southwestern Oregon with high concentrations of nickel, zinc, and chromium, and low calcium to magnesium ratios. Soils inhabited by the three species differed...
The seasonal duration of snow cover is a primary factor influencing the patterns of vegetation in high subalpine and alpine environments, but little is known concerning the responses of plant reproduction and
seedling recruitment to gradients of snow-release. Vegetation patterns of a high subalpine site in the Oregon High Cascades...
Sediment-associated gross primary production, oxygen uptake, microalgal biomass expressed as chlorophyll a concentration, macroalgal biomass and total organic matter concentration expressed as ash-free dry weight were measured monthly at medium sand, fine sand and coarse silt sites between 0.5 m and 2.0 m above MLLW during an entire year at...
Infection courts for microorganisms invading white fir heartwood were determined to be primarily branches and basal wounds. Of 11 hymenomycetes isolated from infected trees, only four: Echinodontiurn tinctorium, Phellinus chrysoloma, Pholiota adiposa, and Hericium abietis were of major significance in terms of frequency of infection and damage caused. Two or...
This dissertation describes patterns in epiphytic macrolichen community composition, diversity, and biomass across various stand types in the Blue River watershed of western Oregon. It first examines the relative importance of ecological factors such as stand age, remnant tree retention, and topography to lichen communities in the landscape. It then...
Since around 1923 Port-Orford-cedar (Chamaecyparis lawsoniana (A. Murray) Parl.) has been affected by Phytophthora root disease caused by the virulent introduced pathogen Phytophthora lateralis. A systematic resistance testing and breeding program located at the USDA Forest Service Dorena Genetic Resource Center in Cottage Grove, Oregon was initiated in 1997 with...
References are given for illustrations in the second edition of Macrolichens of the Pacific Northwest. For each illustration, we list the photographer or illustrator, the specimen photographed, where the specimen was from, collector, collection number, and herbarium.
We list additions, deletions, and other changes in species included in Macrolichens of the Pacific Northwest, 2nd edition, as compared to the 1st edition. The changes resulted from discoveries of range extensions into the Pacific Northwest, descriptions of new species, taxonomic revisions, and nomenclatural revisions.
Papain-like leader proteases are found in diverse families of human, animal, plant, and fungal positive-strand RNA viruses. In addition to autocatalytic processing, these proteases play a variety of roles in the virus life cycle. In particular, the leader protease (L-Pro) of a prototype member of the Closterovirus genus, Beet yellows...
The effects of dwarf mistletoe on fuel in precommercial ponderosa pine stands: Dwarf mistletoe and healthy stands were sampled by vertical planar intercept and whole tree biomass sampling techniques to measure
fuel loading in ground and crown fuels. Differences in size, distribution, and vitality of fuel were shown to depend...
The rate and manner of bioniass loss from decomposing Douglas-fir and western hemlock boles in mid-elevation forests of the central Cascade Range were measured. Bole bark and wood were considered separately. Loss of bole wood due to respiration was measured by change in bole wood density. Loss of bole wood...
The fungal ascomycete genus Otidea as represented in the Pacific Northwest of North America includes eight well known species and two poorly-known species. Cladistic analysis utilizing characters from ribosomal DNA and morphology allowed the development of a robust phylogenetic species concept for Otidea. The combination of characters from the ribosomal...