http://hdl.handle.net/1957/7869 Collection contains recent scholarly output of student majors in the Forest Resources Department Search the Channel search http://ir.library.oregonstate.edu/dspace/simple-search http://hdl.handle.net/1957/9376 Title: Spatial analysis techniques for ensuring the compatibility of land management activities and aquatic habitat quality in eastern Oregon <br/> <br/>Abstract: A land management scheduling model is developed that uses a Tabu search procedure to schedule timber harvests and road management activities, while simultaneously meeting (over time and space) two aquatic goals, and also providing for an even-flow of timber harvest volume. Decision variables include land units and roads, and they are considered to take on integer (0-1) solutions. Decision choices include those that involve land allocation issues (harvest and road obliteration), and those that involve changes in management practices (using lower tire pressures on certain roads to reduce the amount of sediment produced). The scheduling model included provisions for estimating stream sediment and temperature impacts as a result of the spatial location of management activities, and provisions for projecting the growth and yield of timber stands over time using growth rates derived from yield tables. The model uses Tabu search procedures to guide the selection of land management activities, and was applied to a 14,643 acre case study watershed in eastern Oregon. Twenty independent solutions were generated, of which 80 percent were within 10 percent of an estimated global optimum net present value, and all were within 15 percent. Although the limitation to using Tabu search is that one is not assured of obtaining the global optimum solution to a particular problem, the model developed here is an important contribution to forest planning for problems which have 100,000+ integer variables and spatial goals. An analysis of model results showed significant negative correlation between equivalent clearcut acres (ECA), a commonly used measure of cumulative watershed effects, and a stream temperature index. No correlation was observed between ECA, a stream sediment index, and timber harvest volume levels. These results suggest that sediment and temperature index levels may not be good proxies for ECA (or vice versa). Finally, the sensitivity of model results was examined using three different representations of the landscape: (a) vegetation units, (b) soils units, and (c) a combination of vegetation and soils units. Results show significant differences exist in terms of net present value, length of road assigned to central tire inflation use per period, stream sediment and temperature indices, ECA, and timber harvest volume levels. <br/> <br/>Description: Graduation date: 1996 http://hdl.handle.net/1957/9368 Title: Conifer regeneration, understory vegetation and artificially topped conifer responses to alternative silvicultural treatments <br/> <br/>Abstract: Historically, between 40-60% of the Coast Range of Oregon was comprised of structurally diverse, old forests initiated by disturbances of various spatial scales ranging from thousands of acres (large fires) to the size of a single tree (windthrow). The predominant regeneration method of the past several decades, however, has been clearcutting of units that are at least 8 ha in size followed by burning and/or herbicide application and planting of Douglas-fir (Pseudotsuga menziesii) seedlings at high densities. Some question the ability of this regeneration method to provide many of the structural characteristics that existed historically in Pacific Northwest forests. In order to address these concerns, alternative silvicultural practices have been proposed in which green trees and snags are maintained after harvest so that species reliant upon these structures are able to persist through the artificial disturbance. Our research assessed conifer regeneration, understory vegetation, and artificial snag dynamics 16 to 18 years after treatment in clearcuts and two alternative silvicultural regimes: twostory-75% of volume removed resulting in 20 to 30 green trees/ha and group selection- 33% of volume removed in 0.2 to 1.0 ha circular, square, or strip-shaped gaps. All harvested areas were planted with Douglas-fir seedlings and competing vegetation was controlled using herbicide. Uncut controls were included in the study and monitored. Concurrent with harvest, 804 mature Douglas-fir trees were topped both with and without retention of live branches in order to create snags and living character trees. Conifer regeneration growth and survival were greatest in the clearcut treatments, intermediate in the two-story treatment and least in the gaps of the group selection treatment. Gap size was positively correlated with regeneration growth but had no significant effect on survival. Understory vegetation communities were generally resilient to disturbance and silvicultural regime had no effect on either total plant cover or tall shrub cover. More disturbed areas had greater species diversity which was driven largely by greater abundance of exotic ruderals. Young stand development may have had a larger impact on vegetation communities than silvicultural treatment. Twenty-four percent of artificially topped conifers with live branch retention remained living 16 to 18 years after treatment. Only 4% of artificially topped conifers with no live branch retention had broken 16 to 18 years after treatment. DBH of artificially topped conifers was negatively correlated with probability of falling. <br/> <br/>Description: Graduation date: 2009 http://hdl.handle.net/1957/9189 Title: Wildfire risk management : strategic interaction and spatial interdependence <br/> <br/>Abstract: In this dissertation, I examine how the spatial configuration of forest ownership influences the risk-mitigating behavior of public and private forestland owners over time. I determine whether or not the predicted equilibrium outcomes are socially optimal and, if not, whether the introduction of regulation, liability, or private insurance would lead to socially optimal outcomes. Because both individual and collective actions affect wildfire risk, this problem is well suited to game theory and the analysis of strategic behavior. I use a game theoretic framework to examine how the public landowner's investment in fuel management influences, and is influenced by, decisions made by private forestland owners. I find that spatial configuration and location affect the timing and amount of fuel treatment on the landscape. There is less investment in fuel management on landscapes characterized by fragmented ownerships. I also find that the nature of the strategic interaction between landowners depends on whether there are constant, increasing, or decreasing returns to investment in fuel management. To address the inefficiencies in fire risk management, I find that a fuel stock regulation offers the greatest potential to improve outcomes on a landscape with mixed ownership. <br/> <br/>Description: Graduation date: 2009 http://hdl.handle.net/1957/9082 Title: Relationship between allometric variables and biomass in western juniper (Juniperus occidentalis) <br/> <br/>Abstract: A tenfold expansion of western juniper (Juniperus occidentalis spp. occidentalis) into the sagebrush steppe has led to the degradation of the economic and ecological potential of these landscapes. Land managers have enacted numerous methods to reduce distributions and densities of these trees. Assessment of above ground juniper biomass, expressed overall as well as in each of four fuel - size classes is useful information to land managers for several reasons. These include: enhance smoke management for prescribed burns, appraise feasibility of locating biomass cogeneration power plants, and extrapolating known nutrient and carbon concentrations contained within juniper to the landscape scale. Two sites were selected within Lake County, OR for this research. Allometric measurements including canopy area, canopy volume, age, height, basal diameter were taken from 129 trees and 56 of these were destructively sampled to obtain biomass of each tree; by size classes as well as over all. Regression statistics were utilized to find the correlation between allometric and biomass measurements. Of the allometric variables measured for this research, canopy volume, canopy area, and basal diameter were the strongest predictors of biomass found, with respective R2 values of 0.88, 0.87, 0.81. The proportion of biomass within each of the four size classes was: 34% for size class 1, 15% for size class 2, 23% for size class 3, and 28% for size class 4. Average biomass for these sites was 2,482 kg/ha for the Fort Rock site and 5,410 kg/ha for the Lakeview site. These models can be used to estimate biomass for co-generation plants, estimate nutrient pools and fuel loads, and predict changes in community biomass based on species or growth form groups. <br/> <br/>Description: Graduation date: 2009