Research findings from faculty, staff, and students in Forest Engineering, Resources and Management. http://hdl.handle.net/1957/10900 2013-06-20T03:14:34Z 2013-06-20T03:14:34Z Painter, Luke E. http://hdl.handle.net/1957/39456 2013-06-17T21:50:37Z 2013-05-30T00:00:00Z

Trophic cascades and large mammals in the Yellowstone ecosystem Painter, Luke E. Reintroduction of wolves to Yellowstone National Park (YNP) in 1995-96 provided a rare opportunity to observe the response of an ecosystem to the return of a top predator, including possible reversal of decades of decline of aspen, cottonwood, and tall willows suppressed by intensive herbivory on elk winter ranges. To investigate changes in aspen stands in northern Yellowstone since the return of wolves, I compared browsing intensity and heights of young aspen in 87 randomly selected stands in 2012 to similar data collected in the same stands in 1997-98. I also measured the spatial density of elk and bison scat piles as an index to relative population densities, and used annual counts of elk to calculate trends in elk density. In 1998, browsing rates averaged 88%, heights were suppressed, and no tall saplings (≥200 cm) were found in sampling plots. In 2012, browsing rates in 2012 were much lower averaging 44%, and 28% of plots had at least one sapling ≥200 cm, tall enough to escape browsing and therefore more likely to survive to replace dying overstory trees. Heights of young aspen were inversely related to browsing intensity, but not significantly related to leader length, suggesting that differences in height were primarily due to differences in browsing, not factors related to productivity. Aspen recovery was patchy, possibly due in part to locally high elk or bison densities in some parts of the winter range. These results of reduced browsing with increased sapling recruitment were consistent with a trophic cascade from wolves to elk to aspen resulting in a widespread and spatially variable recovery of aspen stands. There was wide variation in browsing intensity and aspen height between sectors of the Yellowstone northern ungulate winter range (northern range). The east sector generally had lower rates of browsing and more stands with tall saplings than the central and west sectors, a pattern that matched recent trends in elk population densities. Only a small minority of stands in the west sector had tall saplings, consistent with higher elk densities in the west. Densities of elk in winter on the northern range recently have been highest in the northwest sector outside the park boundary, where elk benefit from lower wolf densities and milder winters. Aspen stands did not recover at a comparable range-wide elk density when elk were culled in the park in the 1950s and 1960s, suggesting that the influence of wolves may be an important factor in the recent redistribution and reduction of herbivory impacts by elk. To examine the relationship between elk and aspen outside of YNP, I assessed browsing intensity and sapling recruitment in 43 aspen stands in the Shoshone National Forest east of the park, compared to data collected in the same stands in 1997-98. As in northern YNP, results were consistent with a trophic cascade with reduced browsing and increased recruitment of aspen saplings, but aspen recovery was patchy. Elk densities were moderate to high in most of the area, suggesting that the partial aspen recovery may involve a behavioral response to predation or other factors resulting in local variation in browsing impacts. Livestock may also have limited aspen recruitment. Recovery of some aspen stands in the Shoshone National Forest may provide some of the first evidence of a trophic cascade from wolves to elk to aspen outside of a national park, a trophic cascade possibly weakened by the influence of another large herbivore (cattle). Like cattle, bison in northern Yellowstone may have an effect on woody browse plants. Bison have increased in number and may prevent recovery of some aspen stands in places of high bison density. I also examined browsing impacts of bison on willow and cottonwood in the Lamar Valley. To distinguish the effects of bison from those of elk, I compared browsing at different heights on tall willows, below and above the reach of bison. Because elk were absent from the area in summer when bison were present at high density, I also measured browsing that occurred in the summer. I found high rates of summer browsing, and growth of willows and cottonwoods was suppressed in the Lamar Valley. Above the reach of bison (>100 cm), growth was not suppressed and browsing rates were low, suggesting that these plant species have been released from suppression by elk but bison have compensated for some of the reduction in elk browsing. This study provided the first evidence of significant herbivory by bison of woody browse plants in Yellowstone, and revealed some of the complexity of the Yellowstone food web. In summary, these research results support the hypothesis of a trophic cascade resulting from large carnivore restoration and subsequent changes in elk population densities and distribution. The return of wolves may have combined with other factors such as changes in hunting and land ownership, and increased predation by bears, to result in large-scale shifts in the distribution of elk in northern Yellowstone and greatly reduced elk densities in some areas. If these trends continue, the result may be a new alternative state with lower elk densities, and potential for enhanced biodiversity through reduced herbivory of woody browse species. Graduation date: 2013

2013-05-30T00:00:00Z Mouw, Wesley J. http://hdl.handle.net/1957/39209 2013-06-12T15:45:55Z 2013-05-31T00:00:00Z

Encounters, norms, crowding, management, and behavioral responses of visitors at coastal state parks in Oregon Mouw, Wesley J. With the baby boomer cohort retiring and arguably having more time for outdoor recreation, coupled with population increases and government agencies encouraging people to recreate outdoors, areas such as state and national parks will likely continue seeing high visitation. It is imperative, therefore, for outdoor recreation managers and researchers to understand issues related to use levels such as reported encounters, perceived crowding, normative tolerances, and behavioral responses to these conditions. This thesis uses data from visitors at coastal state parks in Oregon to examine: (a) their encounters, norms, and crowding; (b) the proportion of visitors who encounter more people than their normative tolerance, and whether these individuals feel most crowded and are most supportive of direct actions for managing use levels at these parks; and (c) behavioral responses that visitors are likely to impose if their norms are violated, and whether these responses are related to the salience (i.e., importance) of encounters. Data were obtained from questionnaires completed by 9,063 visitors at nine day and 10 overnight state parks on the Oregon coast. Results showed that overnight visitors encountered more people and felt more crowded than day visitors, with 68% of all overnight and 46% of all day visitors feeling crowded. Compared to visitors who encountered fewer people than their normative tolerance, visitors who encountered more people than their norm felt significantly more crowded and were more supportive of strategies for restricting use levels. Day visitors would respond differently than overnight visitors if they encountered more people than they would tolerate seeing (i.e., their norm). Day visitors, for example, would be most likely to avoid peak use times or redefine their experience, whereas overnight visitors would be most likely to express their opinions to those close to them (e.g., friends, family, members of their group). Visitors who indicated that encounters were salient (i.e., important) would be more likely to engage in these behavioral responses than those who did not consider encounters to be salient. These findings also differed among some of the state parks sampled. This thesis contains two standalone articles discussing these findings and their implications for management, theory, and future research. Graduation date: 2013

2013-05-31T00:00:00Z Zamora Cristales, René Arturo http://hdl.handle.net/1957/39180 2013-06-11T17:52:24Z 2013-05-23T00:00:00Z

Economic optimization of forest biomass processing and transport Zamora Cristales, René Arturo An economic analysis and optimization of forest biomass processing and transportation at the operational level is presented. Renewable sources of energy have captured the interest of public and private institutions to develop cost-effective supply chains to reduce dependence on fossil fuels. The production of energy from forest harvest residues constitutes an opportunity to develop a supply chain for producing heat, electricity and liquid fuels from renewable materials. Special interest has been directed to the production of aviation fuel given the characteristics of the commercial aircraft technology that cannot use other renewable sources such as electricity, nuclear power or wind turbines. In economic terms, the production of energy from forest harvest residues at actual market prices requires efficient cost management and planning in order to compete with traditional fossil fuel supply chains. Efficient cost management requires an understanding of the operational stages in order to propose alternatives to improve the planning process, reduce costs, and increase the chance of success of this emerging supply chain. The main goal of this study is to improve cost-efficiency of an emerging energy supply chain from forest harvest residues. A general objective is the economic optimization of forest biomass processing and transportation at the operational level. We developed a model and frame-work to analyze the economics of forest biomass processing and transportation using mixed integer programming (MIP), simulation, Geographic Information Systems (GIS) and forest operation analysis. We developed an economic costing model that accounts for the cost of machinery and truck waiting time. The study is primarily focused on difficult access steep-land regions although it can also be applied to areas with less restricted road access. A stochastic discrete-event simulation model was developed to estimate cost management strategies to improve economics of mobile chipping operations and analyze the effect of uncertainty in this type of operation. The model was successful in predicting productivity of actual forest biomass recovery operations. The model also allowed analyzing the economic effect of truck-machine interactions when using mobile equipment to process the forest residues With stationary processing equipment, the economic effect of truck-machine interactions on closely coupled operations was analyzed through a simulation model. It was demonstrated that truck-machine interactions affect machine utilization rates and, thus, the economics of the operation. Truck-machine interaction must be accounted for when analyzing forest recovery operations to avoid inaccurate cost estimation. Finally a mathematical solution procedure based on mixed integer programming, GIS and simulation was developed to support planning decisions in forest biomass recovery operations, including economic modeling of the effect of waiting times. The solution procedure was incorporated in the decision support system, Residue Evaluation and Network Optimization (RENO) developed in JAVA platform. The decision support system was demonstrated to be an accurate and effective tool to estimate the most cost effective processing machinery and transport configuration given road access, material physical properties, spatial location of the residue piles and accounting for truck-machine interactions. Additionally, an Ant Colony heuristic is included in the model to bring support to the MIP branch and bound solution method by providing an initial solution for objective function. The model is also flexible to user changes to allow the analyst to analyze the sensitivity of the results to main production variables. Graduation date: 2013

2013-05-23T00:00:00Z Brewer, Nolan W. Smith, Alistair M. S. Hatten, Jeffery A. Higuera, Philip E. Hudak, Andrew T. Ottmar, Roger D. Tinkham, Wade T. http://hdl.handle.net/1957/38733 2013-05-28T16:09:33Z 2013-01-08T00:00:00Z

Fuel moisture influences on fire-altered carbon in masticated fuels: An experimental study Brewer, Nolan W.; Smith, Alistair M. S.; Hatten, Jeffery A.; Higuera, Philip E.; Hudak, Andrew T.; Ottmar, Roger D.; Tinkham, Wade T. Biomass burning is a significant contributor to atmospheric carbon emissions but may also provide an avenue in which fire-affected ecosystems can accumulate carbon over time, through the generation of highly resistant fire-altered carbon. Identifying how fuel moisture, and subsequent changes in the fire behavior, relates to the production of fire-altered carbon is important in determining how persistent charred residues are following a fire within specific fuel types. Additionally, understanding how mastication (mechanical forest thinning) and fire convert biomass to black carbon is essential for understanding how this management technique, employed in many fire-prone forest types, may influence stand-level black carbon in soils. In this experimental study, 15 masticated fuel beds, conditioned to three fuel moisture ranges, were burned, and production rates of pyrogenic carbon and soot-based black carbon were evaluated. Pyrogenic carbon was determined through elemental analysis of the post-fire residues, and soot-based black carbon was quantified with thermochemical methods. Pyrogenic carbon production rates ranged from 7.23% to 8.67% relative to pre-fire organic carbon content. Black carbon production rates averaged 0.02% in the 4-8% fuel moisture group and 0.05% in the 13-18% moisture group. A comparison of the ratio of black carbon to pyrogenic carbon indicates that burning with fuels ranging from 13% to 15% moisture content resulted in a higher proportion of black carbon produced, suggesting that the precursors to black carbon were indiscriminately consumed at lower fuel moistures. This research highlights the importance of fuel moisture and its role in dictating both the quantity and quality of the carbon produced in masticated fuel beds. Citation: Brewer, N. W., A. M. S. Smith, J. A. Hatten, P. E. Higuera, A. T. Hudak, R. D. Ottmar and W. T. Tinkham (2013), Fuel moisture influences on fire-altered carbon in masticated fuels: An experimental study, J. Geophys. Res. Biogeosci., 118, 30-40, doi:10.1029/2012JG002079. This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://www.agu.org/journals/jgr/.

2013-01-08T00:00:00Z