This thesis presents methods for obtaining asymptotically efficient and consistent parameters and variance estimates for simultaneous equations in a forest growth modelling context. Ordinary Least Squares (OLS), Seemingly Unrelated Regressions (SUR), Two-Stage Least Squares (2SLS) and Three- Stage Least Squares (3SLS) are presented for linear models. The variables, model types...
Forest managers are beginning to take an interest in management of young Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) in Western Oregon and Washington. Studies have established the relationship between growth and levels-of-growing-stock but few have established a link to wood quality and value. This study used data collected from a long...
This study examined the abundance, size, growth, and age of advance regeneration
Douglas-fir, beneath an eighty year-old overstory at a single site on plots subjected to different overstory thinning treatments. Treatments consisted of keeping overstory basal area within upper and lower limits for periods of 12-17 years which, depending upon...
Temperate coniferous forests, such as those that cover vast areas of the western US and Canada, have evolved to depend on cycles of disturbance for succession of species and overall ecosystem maintenance. Many of these forest systems are managed, often for timber production, where disturbances are of anthropogenic origin and...
Soil nitrogen exists largely as organic matter, including plant liter, dead animal matter, and microbial necromass. About 90% of soil organic nitrogen is proteinaceous material that is too large for plants and microorganisms to assimilate directly. Protein depolymerization therefore plays a critical role in mobilizing this organic source of nitrogen,...
Algae can be used in a variety of wastewater systems to capture nutrients while fixing carbon dioxide from the atmosphere. I conducted field trials at three locations in Oregon with both corn and potato crops to assess the agronomic value and environmental impact of using the resulting algal biomass as...
Prior to 2005, ammonia oxidation, the first step of nitrification, was thought mediated mainly by ammonia-oxidizing bacteria (AOB). However, the discovery of Thaumarchaeota carrying the genes coding for the ammonia monooxygenase (AMO) enzyme led to the discovery that ammonia-oxidizing archaea (AOA) also contribute to nitrification. Despite the uptick in studies...
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DavidD. Myrold
Prior to 2005, ammonia oxidation, the first step of nitrification, was
Nitrification and denitrification are major biological processes transforming nitrogen (N) in soils to plant available N, highly leachable nitrate (NO₃⁻) and gaseous N oxides. Although many studies in the past have studied N cycling communities, the effect of increased N inputs on ammonia-oxidizer and denitrifier population dynamics is still under...
Forests are one of the largest repositories of terrestrial C. Understanding factors that drive organic matter transformations and nutrient efflux from these systems is therefore highly important. Temperate forests are of particular significance due to the large fraction of C that is stored below ground in the soil. Characterizing nutrient...
Algae have shown great potential as a source for renewable fuels. However, current production schemes have not been able to prove a sustainable energy return on investment due in part to the high costs of nutrient addition and the energy required for drying the biomass. Integrated algae-dairy production systems have...
