Western juniper (Juniperus occidentalis) poses both a challenge and an opportunity for natural resource management in the rangelands of the northern Great Basin. The continued expansion of western juniper on the rangelands of the interior Northwest will likely continue as there are currently no practical options for returning this area...
Greater Sage-grouse (Centrocercus urophasianus) habitat research has historically focused on fine-scale (0.007 - 0.032 ha) vegetation structure and composition immediately surrounding sites selected by birds. However, little work has evaluated vegetation attributes important for Greater Sage-grouse at a landscape-scale or identified landscape attributes that influence habitat use patterns. Habitat use...
Greater sage-grouse (Centrocercus urophasianus), a sagebrush obligate species, has contracted in extent by nearly half its original distribution. This is primarily due to habitat loss and degradation over the past 150 years. During winter, sage-grouse depend completely on sagebrush habitat for food and cover, yet sage-grouse winter ecology has been...
This study examines the long-term role of interference on stand development of Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) and red alder (Alnus rubra Bong.) planted mixtures in the Central Cascades of Oregon, USA. The two species are common associates in naturally regenerated and planted conifer stands in the Pacific Northwest. Due...
Silvicultural canopy gaps are emerging as an alternative management tool to accelerate development of complex forest structure in young, even-aged forests of the Pacific Northwest. I investigated patterns of nitrogen (N) availability along transects through 0.1 and 0.4 ha silvicultural gaps in three 50-70 year old Douglas-fir forests of western...
While damages due to ponding are common and expensive, provisions for design and
construction of flat roof systems lack guidance regarding these loads. The goal of this research is
to present methods of designing or building flat roofs that are less vulnerable to this condition. An
investigation of the literature,...
The mechanisms of substrate recognition by regulatory proteases are not well understood. Presently, two opposing models have arisen to describe E. coil Lon's ability to discriminate between substrates: one suggests the N-terminus involvement while the second suggests the C-terminus involvement. In this project, the role of the C-terminal domain as...
Wildtype sunflower typically produces 12-24% oleic acid (18:1) and 70-82%
linoleic acid (18:2). High-oleic sunflower, by contrast, produces up to 80-94% oleic
acid. The monounsaturated oleic acid has a greater oxidative stability than the
polyunsaturated linoleic acid, predominant in wildtype sunflower, and has greater
nutritional benefits than polyunsaturated and saturated...
Cultivated meadowfoam (Limnanthes alba Benth.) is an annual oil seed crop native to southern Oregon. California and British Columbia. The genus Limnanthes is composed of nine species and divided into two sections, Inflexae and Reflexae. The seed oil of meadowfoam is a rich source of erucic acid and several novel...
Tocopherols are plant secondary metabolites that are known collectively as
vitamin E. Tocopherol compounds act as potent antioxidants by quenching free
radicals and protecting fatty acids from oxidative damage. In humans (in vivo)
tocopherols protect membrane lipids from breaking down, while in oils (in vitro)
tocopherols protect fatty acids from...
The cultivated sunflower (Helianthus annuus L., x=17) is one of the most important annual oilseed crops in the world. There are very few publicly shared sequence-based DNA markers and genetic maps in sunflower, even though molecular DNA markers and genetic maps have become widely used in all areas of genetic...
Understanding how N availability influences base cation stores is critical for long-term ecosystem sustainability. Indices of nitrogen (N) availability and the distribution of nutrients in plant biomass, soil, and soil water were examined across ten young, unpolluted Douglas-fir (Pseudotsuga menziesii) stands in the Oregon Coast Range spanning a three-fold soil...
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Steven S. Perakis
Understanding how N availability influences base cation stores is
Although previous research in central Oregon has shown soil compaction can lead to a decline in site productivity, the subject is not understood well enough to predict the growth changes resulting from a given level of soil compaction. A study was initiated to relate the basal area, height and volume...
Single nucleotide polymorphisms (SNPs) are the most common DNA polymorphisms in plant and animal genomes. SNPs were identified in the allele sequences of up to 12 sunflower (Helianthus annuus L.) genotypes for a genome-wide sample of 81 loci originally mapped using restriction fragment length polymorphism (RFLP) markers. The RFLP loci...
Medium chain fatty acids (MCFAs) are important industrial feedstocks for
soaps, detergents and surfactants. Interspecific lines derived from Cuphea lanceolata
and Cup hea viscosissima are being domesticated as a temperate source of MCFAs.
These species also serve as model organisms for understanding the biosynthesis of
MCFAs in seeds. Various markers...
Microsatellites or simple sequence repeats (SSRs) are highthroughput sequence based DNA markers that have been exploited as tools for measuring genetic distance and diversity in evolutionary studies, protection of intellectual property, genetic resource conservation management, cultivar identification and molecular breeding of crop plants. We isolated and sequenced 1095 clones from...
Black rockfish (Sebastes melanops) is an important marine recreational species throughout the Pacific Northwest. Recent catch data indicate a trend of age-truncation in the black rockfish population off the Oregon coast, with older females rapidly disappearing from the population. In populations with broad age distributions, older fish may contribute disproportionately...
Meadowfoam (Limnanthes alba Bentham; Order: Brassicales; Family: Limnanthaceae) is a self-compatible, predominantly allogamous, insect pollinated species. Meadowfoam oil is a source of novel unsaturated very-long-chain (VLC) seed oils (C₂₀ and C₂₂) with low concentrations of saturated fatty acids (typically less than 2%) and outstanding oxidative stability. Here we report the...
Fire is a major disturbance process in many forests. Long-term studies of the biogeochemical effects of fires, especially on soils, are very rare.
Consequently, long-term effects of fire on soils are often hypothesized from
short-term effects. In a chronosequence study, I studied 24 western Cascades
(Oregon) forest stands thought to...