OREGON STATE UNIVERSITY

OSU Research Projects

Sub-plot variation of nutrient distribution in Douglas-fir plantations

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This study will use geostatistical analysis to investigate the causes of sub-stand-scale variability of forest soil nutrient content in Pacific Northwest Douglas-fir plantations. Soil is notoriously heterogeneous and variation of nutrient content can be large within even a single forest stand. In surveys of plot health, soil samples are typically composited to generate a mean value for the site. This ignores the variability, which can be substantial (>40% coefficient of variation). Characterizing the overall variation and spatial distribution of nutrient content will enable forest managers to consider precision silvicultural treatments, and correlating spatial distribution to environmental factors will further knowledge of small-scale pedogenesis.

Student Researchers
Maxwell Taylor

Sediment transport in riverine systems using a node-based approach to river modeling

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The role of network structure in Organic Carbon Dynamics in Fluvial Hydrosystems: Fluvial hydrosystems are composed by NETWORKS of fluvial corridors (i.e. river/stream reaches) and the surrounding watersheds. The network structure is a recurrent pattern in nature that could be optimized for multiple functions including transport, processing and energy production. Fluvial hydrosystems have been recently recognized as important components of the global carbon cycle –core topic in climate change science. However most of our understanding about them comes from a linear perspective that compares them with ‘pipes’, neglecting the role of network structure (Aufdenkampe et al., 2011). To fully understand how fluvial hydrosystems could respond to global enviromental changes is key to gain insights into the constraints that network structure imposes on fluvial hydrosystem functioning.

Student Researchers
Francisco Guerrero

Lake sediments as evidence of environmental change

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This project focuses on studying lake sediments as evidence of environmental change. The Oregon Coast Range is a useful place to study this since it experiences strong forcings – storms, earthquakes, fires, and human land use. By studying sediments of lakes in this steep, dissected mountain range, we can capture a record of river basin events and an expression of their associated delivery mechanisms, as well as relative and absolute changes in rates of sediment accumulation. We have chosen to take sediment cores from Loon Lake, Umpqua River Basin, and date and analyze them, as well as study the catchment’s past history. A current view of hydrologic process will inform us of sediment delivery, so we propose to monitor water and sediment discharge. Because physical processes within lakes act as filters between the external forcings and the sedimentary record, this is being proposed to being investigated. Similarly, because diagenic processes within the sediments determine their form and composition, biogeochemical processes of sedimentation are being proposed to be studied as well.

Publications
Student Researchers
Kristin Duckworth

Soil nutrient and moisture dynamics following two years of loblolly pine-switchgrass co-culture

Co-culture systems incorporating both forest and grassland characteristics could positively impact soil quality and diversify income earning potential compared to monoculture. However, the intensive nature of such a system may stimulate interspecific competition for soil resources, and have long-term impacts upon timber and bioenergy feedstock production. To evaluate interspecific mechanisms within such a system, we established and monitored two loblolly pine-switchgrass co-cultures in northeastern Mississippi across varying competitive intensities.

Student Researchers
Kurt J. Krapfl