Thesis (M.S.)--Oregon State University, 1980. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.

Thesis (Ph. D.)--Oregon State University, 1983. / Typescript (photocopy). Includes bibliographical references (leaves 202-218). Also available on the World Wide Web.

Thesis (M.S.)--Oregon State University, 1983. / Typescript (photocopy). Includes bibliographical references (leaves 58-62). Also available on the World Wide Web.

No description available.

Thesis (Ph. D.)--Oregon State University, 2001. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.

Thesis (Ph. D.)--Oregon State University, 2002. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.

No description available.

In the wildfire community fuel moisture content (FMC) is the quantity of choice when it comes to assess vegetation water status in relation to fire risk and fire behaviour. Field measurements of FMC are both expensive and time consuming and, in addition, sampling is often spatially inadequate. Remote sensing could represent an almost ideal solution both in terms of spatial and temporal coverage, if a consistent relationship between FMC and spectral reflectance could be established. A review of the literature suggests that it is difficult to retrieve FMC for dense forest canopies with remote sensing platforms. This study took a step back and explored the relationship between spectral reflectance and vegetation water content at the leaf level, where several confounding factors present at the canopy level are eliminated or controlled for. It also considered a conifer species, because relatively little research has been produced on this topic for this type of vegetation. The main goal was to establish if FMC can be derived directly from spectral reflectance in the solar spectrum using two well known approaches, such as spectral indices and continuum removal. It is also aimed at exploring if an alternative, indirect way to measure FMC as ratio of Equivalent Water Thickness (EWT) and Specific Leaf Weight (SLW) is feasible and accurate. The results derived from Douglas-fir (Pseudotsuga menziesii (Mirb) Franco) needles used in this study suggested that FMC was not directly retrievable from spectral reflectance but vegetation water content could be assessed with sufficient accuracy in terms of EWT. Also the retrieval of SLW from reflectance of fresh foliage proved to be challenging. Finally, the study also highlighted several aspects in the relationships among foliar water content, dry matter content and reflectance that require additional research. / Graduate

Graduation date: 1966

The effect of defoliation intensity and season on Douglas-fir growth were studied in three replications in the Siuslaw National Forest during 1988-1990. Four intensities of defoliation were applied once in either spring or summer 1988. Stem diameter and canopy area were linearly inversely proportional to the level of defoliation. Defoliation intensity did not affect height growth (P > 0.05). Greater losses in height occurred when seedlings were defoliated in spring than in summer. No differences in predawn and mid-day xylem water potential were observed between trees defoliated in summer or spring 1988. However, in 1989, 25% defoliation reduced mid-day moisture stress whereas 50 and 75% defoliation increased mid-day moisture stress (P < 0.05). Effects of defoliation on length, width, and area of dominant and subdominant twigs as well as number of twigs were separated into different whorls. As indicated by the sharp slopes of the response surfaces, spring defoliation affected seedlings more (P < 0.5) than summer defoliation. No season or intensity effects (except second whorls) on area of dominant twigs were carried over to 1990. No effects (P > 0.5) of season or intensity on twig width were observed in 1990. Subdominant twigs were generally more sensitive to defoliation than dominant twigs. Greater losses (P < 0.5) in area of subdominant twigs occurred when seedlings were defoliated in spring than in summer. Similar to area, length of twigs continued to respond to defoliation intensity in 1990. Length and width of dominant and subdominant twigs were smaller for spring compared to summer defoliated trees. Number of twigs were linearly inversely proportional to the level of defoliation intensity in 1989. Intensity did not affect number of twigs in 1990 except second whorls. No effect of defoliation intensity and season on new whorls was detected. / Graduation date: 1992