Soil respiration, or the combined CO₂ emissions from roots and soil microorganisms, constitutes one of the largest losses of carbon (C) from terrestrial ecosystems. The major drivers of soil respiration, which include soil moisture, temperature, and substrate quality, have been known for some time. Nevertheless,
correlations between these drivers and...
My objectives were to investigate the correlation of height and diameter growth in young Douglas-fir (Pseudotsuga menziesii) plantations with stand density, and to determine the effects of stand density on the canopy boundary layer conductance (g[subscript]ac) and microclimate characteristics of young Douglas-fir plantations. I measured annual height (h) and diameter...
Canopy structure has a significant impact on the canopy hydrology of
Douglas-fir forests in the Pacific Northwest (PNW). Whole canopy rainfall
interception was measured for young Douglas-fir forest and compared to an
old-growth Douglas-fir forest. The old-growth forest had significantly greater
canopy water storage capacity (5) and direct throughfall fraction...
Many studies have shown that net primary production in old-growth Douglas-fir/western hemlock forests is lower than in younger forests in similar sites, although the cause is still not clear. One possibility is that overall carbon assimilation, or GPP, is lower in older forests. However, it is difficult to measure GPP...
Soils are the largest terrestrial pool of carbon, therefore it is critical to understand
what controls soil carbon efflux to the atmosphere in light of current climate uncertainty.
The primary efflux of carbon from soil is soil respiration which is typically categorized
into autotrophic and heterotrophic respiration. These two components...
The goal of this dissertation was to improve our understanding of age-related constraints on aboveground production of forest trees. Previous research suggesting that carbon uptake of old trees is hydraulically constrained by tree size was used as the
springboard for this research. Three specific working hypotheses were investigated: 1) compensation...
Exotic ponderosa pine (Pinus ponderosa Doug. ex Lawson) plantations are being planted within the natural distribution area of cordilleran cypress (Austrocedrus chilensis (D.Don) Pic. Ser. et Bizzarri) in Patagonia, Argentina. The productivity of these exotic plantations is much greater than that of native forests, suggesting greater water use. Before these...
Soil CO2 efflux is a major contributor of CO2 to the atmosphere. The rate that CO2 is respired out of the soil is called the soil flux (Fs). Many variables alter Fs. These variables differ drastically in the variety of ecosystems found on the earth. It is important to understand...
Warming of the terrestrial biosphere due to the anthropogenic addition of carbon dioxide to the earth’s atmosphere is becoming a major focus of scientific inquiry. Predictions of the extent of this warming are hampered by uncertainty in the ability of the earth’s ecosystems to counteract this effect by sequestering carbon...
Rainfall interception is a primary control over the moisture input to a forested ecosystem through the partitioning of precipitation into throughfall, stemflow, and an evaporated component (i.e. the interception loss). Rainfall interception is a spatially and temporally varying process at multiple scales, but heterogeneity in interception processes are poorly understood...
The links between forests, streamflow, and climate are poorly understood. Despite hundreds of studies over the past 60 years, fundamental questions of forests' effects on the hydrologic cycle remain unanswered. The hydrological cycle involves mutually-dependent biological and physical processes that operate at multiple scales of time and space, and this...
I compared transpiration among different types of forest stands in the western Cascades of Oregon. The three major questions were: 1) How does transpiration compare between a young and old stand and why? 2) Does diversity of overstory trees affect transpiration? and 3) How is transpiration related to stream flow?...
The remodeling of the central nervous system (CNS) during metamorphosis in Drosophila melanogaster is a prime model system in which to study the genetic control of the sexual dimorphisms in the abdominal ganglion of the CNS. I have been using a P[tau-lacZ] enhancer trap line, 4.078, to label a segmentally...
Geochemical characterization methods are commonly used in the reconstruction of prehistoric raw material use and procurement systems. Trace element studies of lithic source material and artifacts, specifically those made of obsidian, can reveal important information about the environmental and cultural factors which influence the prehistoric distribution of raw material. The...
Since the late 1970s, archaeology has grown into an industry whose
practitioners work in both public and private sectors. As an industry, modern
archeology is commonly known as Cultural Resources Management, or CRM. CRM
emerged from a surplus of employment opportunities made available to archeologists
after the passing of National...
The fruitless (fru) gene in Drosophila melanogaster is a multifunctional gene having sex-specific functions in the regulation of male sexual behavior and sex-nonspecific functions affecting adult viability and external morphology. While much attention has focused on fru's sex-specific roles, little is known about its sex-nonspecific functions. The embryonic central nervous...
The purpose of this research was to see if there were technological differences in ground stone manufacturing and use from a single site that had been occupied for over 600 years, A.D. 550-A.D. 1150, and had multiple occupations that evolved over time (Late Pithouse Phases, Georgetown, San Francisco, and Three...
The prehistory of Central Oregon is explored through the examination of six archaeological sites and two isolated finds from the Upper Deschutes River Basin. Inquiry focuses on the land use, mobility, technological organization, and raw material procurement of the aboriginal inhabitants of the area. Archaeological data presented here are augmented...
Courtship and copulation behaviors in Drosophila melanogaster males are regulated by sex-specific products from the gene fruitless (fru). Male-specific FRU proteins (FRU[superscript M]) are putative transcription factors of the BTB-ZnF family that likely act by controlling development and maintenance of the neural circuitry used during male sexual behavior. However, which...
In the past, archaeological investigations have recovered material culture that have often been stored as museum property without a focused analysis or written report of the results. This study focuses on one such assemblage ofchipped stone projectile points from the Bachman Cave locality of southwestern Idaho that has been stored...
With human activity causing increases in turbidity in coastal marine waters, it is of economic and ecological importance to understand how this increase will affect organisms living in these areas. At most risk may be predators, such as many teleosts and cephalopods, reliant on vision to detect and capture prey....
CantonS wild-type flies were used to determine sex-specific differences in the daily
locomotor activity patterns in males and females. Under light entrainment, when flies are
kept in a 12:12 light-dark condition, both males and females showed bimodal activity
with a morning peak around lights-on and an evening peak around lights...
Bone Cave is located in the High Lava Plains of Central Oregon, just east of Bend. Excavations were conducted at the site to examine the extent of looter disturbance, and to address research questions focused on prehistoric settlement and subsistence. In the excavation of more than 10 m3 of sediment...
Heartwood can have properties that are distinct from sapwood,
including resistance to insect and microbial attack. Despite the practical
importance of heartwood formation in trees, a review of the literature revealed
that little was known about the effects of environmental factors on heartwood
quality or how variations in heartwood properties...
This study examined the decay resistance of the pine and maple components of wood plastic composites (WPC' s) of varying thicknesses exposed on several culture media to wood decay fungi under laboratory conditions. The ability of malt agar extract (MEA), potato dextrose agar (PDA), amended basal salts, sawdust (maple and...
