Thesis (M.S.)--Humboldt State University, 2006. / Includes bibliographical references (leaves 25-27). Also available via Humboldt Digital Scholar.

Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 107-117). Also available on the World Wide Web.

The accurate simulation of snowpack deposition and ablation beneath forested areas is confounded by the fact that the vegetation canopy strongly affects the snow surface energy balance. The canopy alters the radiation balance of the snowcover, and reduces the wind speed at the snow surface. Data collected as part of the BOREAS experiment are used to analyze the effects of a variety of forest canopies on the climate at the snow surface. Simple algorithms are developed and used to adjust climate data collected above forest canopies to the snow surface. A 2-layer coupled energy- and mass-balance snowmelt model is used to simulate the deposition and ablation of the snowpack at five forested sites within the Canadian boreal forest for the 1994-1995 snow season. Results of the snowcover simulations indicate that the net snowcover energy balance remains close to zero for the winter months, but exhibits a sharp increase in the spring months. The rapid energy gain in the spring is strongly controlled by canopy cover, and is dominated by net radiation fluxes, with minor contributions from sensible, latent, soil, and advected energy fluxes. Net snowcover irradiance dominates during the spring months due to increased solar intensity and longer day lengths, coupled with increased radiation transmission through canopies at high sun angles, and reduced snowcover albedo resulting from the deposition of fine organic debris. Turbulent (sensible and latent) energy fluxes comprise a relatively minor portion of the net snowcover energy exchange, indicating that the sub-canopy snowcover is relatively insensitive to the meteorological parameters controlling these fluxes. The low thermal conductivity of organic-rich boreal soils must be considered for studies focusing on snowcover development when soil heat flux comprises a large portion of the snowcover energy balance. Model outputs at all sites generally show good agreement with measured snow depths, indicating that the techniques used in these investigations accurately simulate both the deposition and ablation of seasonal snowcovers. Results indicate that snowcovers in the boreal environment may be more sensitive to land-use transitions, rather than climate shifts, due to the strong control exerted by vegetation canopies on radiation transfer processes. The results also suggest that simple canopy adjustment algorithms may be effectively applied to spatially distributed snowcover simulations. More data is required to evaluate the accuracy of these methods for computing energy transfer within canopies having significantly different structures than the sites used in this study. / Graduation date: 1999

Graduation date: 1992

Tree-rings were analyzed to assess the relative importance of slope position and aspect as determinants of the climate-sensitivity of sugar maple and white oak radial growth. Tree size, crown condition, forest and soil composition, and site indices were assessed to document environmental differences between site-types and to verify similarity of stands within the same site-type. Climate-sensitivity was assessed using mean between-tree correlation, principal components analysis, mean sensitivity, regression analysis, and analysis of radial growth decline after severe drought. Ecological differences were found between high and low sites on north and south facing aspects. Sugar maple did not exhibit greater climate-sensitivity than white oak. Both species showed greater climate-sensitivity on upper and south-facing slopes. / Department of Biology

Thesis (Ph. D.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 116-126). Also available on the World Wide Web.

Thesis (M.S.)--Mississippi State University. Department of Geosciences. / Title from title screen. Includes bibliographical references.

Thesis (Ph. D.)--University of Canterbury, 2009. / Typescript (photocopy). Includes bibliographical references (leaves 116-118). Also available via the World Wide Web.

Thesis (Ph. D.)--University of Oregon, 2006. / Typescript. Includes vita and abstract. Includes appendices with Foy Lake pollen and charcoal data and fire atlas metadata. Includes bibliographical references (leaves 233-244). Also available for download via the World Wide Web; free to University of Oregon users.

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