Thesis (M.S.)--University of Wisconsin--Stevens Point, 2009. / Submitted in partial fulfillment of the requirements of the degree Master of Science in Natural Resources (Forestry), College of Natural Resources. Includes bibliographical references (leaves 82-87).

Thesis (Ph. D.)--University of Hawaii at Manoa, 2003. / Includes bibliographical references.

<p> Historically, black bears occurred throughout Mississippi but by 1932, &lt;12 bears remained. Repatriation in neighboring states and conservation efforts in Mississippi have led to the recolonization of at least 2 subspecies (<i>U. a. luteolus</i> and <i>U. a. americanus</i>) of black bears in the state. I compiled available data to provide a synthesis of the history, current status, and management of black bears in Mississippi. Additionally, I used global positioning data collected from radio collared bears to determine the influence of distance to source population, cover type, distance to roads, distance to water, wetland reserve program areas, and human population density on black bear resource selection at various spatial scales. I studied characteristics of space use and resource selection of recolonizing bears in the Mississippi Alluvial Valley (Delta). I assessed the influence of environmental parameters at the female core annual home-range (using 50% kernel density estimator) and male and female seasonal and annual home-ranges (95% kernel density estimator). Distance to source population and distance to roads had significant influence at the core female home-range scale. I found a sex-based difference in annual and seasonal home-ranges. I also found that bears exhibited response to and selection for specific resources with an affinity toward hardwood stands, particularly young-aged hardwoods. My research illustrates the importance of analyzing resource selection at multiple scales to gain a full understanding of parameters that influence the recolonization of a bear population.</p><p>

As the global population continues to increase, so will the demand for timber (and other raw materials) for building, construction, and also for the pulping industry. The high demand for wood and the increasing human population mean that natural forests are being lost and degraded. A potential solution to this problem is to improve the productivity of our plantation forests to relieve the pressure on natural forests in terms of sustainable wood production. This project is the first to use newly available microarray technology to study differential gene expression in cambial tissue of high versus low wood density field grown samples from two contrasting species, Sitka spruce (gymnosperms) and poplar (angiosperms). Genes up-regulated in high-density Sitka spruce and poplar samples had functions in cell formation and expansion, with down-regulated genes having functions in lignin biosynthesis, stress-response and defence. Plantation trees could be screened at a young age to assess their expression of candidate genes to speed up the breeding and selection process.

No description available.

This study examines the importance of short-term climate variability when simulating forest succession using ecological process models. A version of the FORSKA2 forest gap model was modified for use with daily climate data and applied along a transect of sites crossing the boreal region in central Canada, including the aspen-parkland and forest-tundra ecotones where impacts of climatic change on forest ecosystems could be particularly significant. The model's sensitivity to forcing with daily climate observations compared to monthly mean and long term averages of monthly mean climate data was investigated. Inclusion of daily climate (minimum and maximum temperature and total precipitation) improved the simulations of key characteristics of present-day forest along the transect, and was particularly important at the ecotones. The results demonstrate that changes in variability associated with future change in mean climate are likely to be important when trying to predict boreal forest responses to projected future climate change. Ideally, the use of projected daily climate data or data based on the statistical characteristics of daily climate is highly recommended for future impact studies. A number of approaches to further improve the functioning of the model are also presented.

<p> Over the past century in the western United States, warming has produced larger and more severe wildfires than previously recorded. General circulation models and their ensembles project continued increases in temperature and the proportion of precipitation falling as rain. Warmer and wetter conditions may change forest successional trajectories by modifying rates of vegetation establishment, competition, growth, reproduction, and mortality. Many questions remain regarding how these changes will occur across landscapes and how disturbances, such as wildfire, may interact with changes to climate and vegetation. Forest management is used to proactively modify forest structure and composition to improve fire resilience. Yet, research is needed to assess how to best utilize mechanical fuel reduction and prescribed fire at the landscape scale. Human communities also exist within these landscapes, and decisions regarding how to manage forests must carefully consider how management will affect such communities. </p><p> In this work, I analyzed three aspects of forest management at large spatiotemporal scales: (1) climate effects on forest composition and wildfire activity; (2) efficacy of fuel management strategies toward reducing wildfire spread and severity; and, (3) local resident perspectives on forest management. Using a forest landscape model, simulations of forest dynamics were used to investigate relationships among climate, wildfire, and topography with long-term changes in biomass for a fire-prone dry-conifer landscape in eastern Oregon, United States. I compared the effectiveness of fuel treatment strategies for reducing wildfire under both contemporary and extreme weather. Fuel treatment scenarios included &ldquo;business as usual&rdquo; and strategies that increased the area treated with harvest and prescribed fire, and all strategies were compared by distributing them across the landscape and by concentrating them in areas at the greatest risk for high-severity wildfire. To investigate local community preferences for forest management, I used focus groups, interviews, and questionnaires. Through open-ended questions and a public participation geographic information systems (PPGIS) mapping exercise, local residents expressed their views on fuels reduction treatments by commercial and non-commercial harvest and prescribed fire. Emergent themes were used to inform alternative management scenarios to explore the usefulness of using PPGIS to generate modeling inputs. Scenarios ranged from restoration-only treatments to short-rotation commercial harvest. </p><p> Under climate change, wildfire was more frequent, more expansive, and more severe, and ponderosa pine expanded its range into existing shrublands and high-elevation zones. There was a near-complete loss of native high-elevation tree species, such as Engelmann spruce and whitebark pine. Loss of these species were most strongly linked to burn frequency; this effect was greatest at high elevations and on steep slopes. </p><p> Fuel reduction was effective at reducing wildfire spread and severity compared to unmanaged landscapes. Spatially optimizing mechanical removal of trees in areas at risk for high-severity wildfire was equally effective as distributing tree removal across the landscape. Tripling the annual area of prescribed burns was needed to affect landscape-level wildfire spread and severity, and distributing prescribed burns across the study area was more effective than concentrating fires in high-risk areas. </p><p> Focus group participants generally approved of all types of forest management and agreed that all areas should be managed with the &ldquo;appropriate&rdquo; type of treatment for each forest stand, and that decisions about management should be made by &ldquo;experts.&rdquo; However, there was disagreement related to who the &ldquo;experts&rdquo; are and how much public input should be included in the decision making process. Degree of trust in land management agencies contributed to polarized views about who the primary decision makers and what the focus of management should be. While most participants agreed that prescribed fire was a useful tool for preventing wildfire spread and severity, many expressed reservations about its use. </p><p> I conclude that forest management can be used to reduce wildfire activity in dry-mixed conifer forests and that spatially optimizing mechanical treatments in high-risk areas can be a useful tool for reducing the cost and ecological impact associated with harvest operations. While reducing the severity and spread of wildfire may slow some long-term species shifts, high sub-alpine tree mortality occurred under all climate and fuel treatment scenarios. Thus, while forest management may prolong the existence of sub-alpine forests, shifts in temperature, precipitation, and wildfire may overtake management within this century. The use of PPGIS was useful for delineating the range of forest management preferences within the local community, for identifying areas of agreement among residents who have otherwise polarized views, and for generating modeling inputs that reflect views that may not be obtained through extant official channels for public participation. Because the local community has concerns about the use of prescribed fire, more education and outreach is needed. This may increase public acceptance of the amounts of prescribed fire needed to modify wildfire trajectories under future climate conditions.</p><p>

Abstract not available.

Selection-cutting is the preferred method of logging in northern hardwood forests, because it is thought to favor the regeneration of valuable, shade-tolerant trees, maximize long-term productivity, and increase the health, quality and economic value of residual trees. Claims have also been made for the ecological sustainability of selection cutting, in particular that it: (a) preserves soil fertility; (b) maintains natural canopy composition; (c) protects plant and animal habitat. I evaluated these claims by studying the effects of selection-cutting on several measures of soil fertility (Ca, Al, Ca/Al molar ratios, pH), canopy composition and tree regeneration, herbaceous layer composition, and structural features related to habitat quality (cavity trees, snags, coarse woody debris) in 55 stands ranging from newly cut to old-growth (not all data overlaps). I found that forest growth after selection-cutting depletes soil solution calcium and lowers soil solution Ca/Al molar ratios, posing a threat to long-term forest health and productivity, particularly at higher elevations and in sites on siliceous bedrock. I found that selection-cut stands dominated by red oak (Quercus rubra) are converting to sugar maple (Acer saccharum) stands, posing a threat to both canopy and herbaceous layer diversity. I found no lasting effects of selection-cutting on herbaceous layer composition, diversity or quality, but I found indirect threats from the conversion of red oak stands to sugar maple and from depletion of soil solution calcium. Finally, I found that current selection-cutting practices generally do not meet published targets for large trees, cavity trees, snags and coarse woody debris, but that they probably could meet those targets with minor changes to cutting practices. I conclude by discussing the implications of these results for the management of northern hardwood forests.

The introduction of Sitka black-tailed deer, Odocoileus hemionus sitkensis Merriam, to Haida Gwaii (Queen Charlotte Islands, B.C., Canada) in the late 19th century provides a valuable opportunity to understand the long-term effects of deer populations on the vegetation of the North American temperate rain forest. We conducted two island-based experiments to investigate the effect of Sitka black-tailed deer on the forest understorey vegetation of this archipelago. In the first experiment we used a set of seven small islands (&lt;15 ha) with different browsing histories (more than 50 years of deer presence, less than 20 years of deer presence, and no evidence of any deer presence) to test the effects of deer on plant cover, species richness and community composition. Browsing history was inversely proportional to both vegetation cover and plant species richness. Modification of the forest understorey plant communities followed a series of steps towards a greatly simplified community of plants possessing mechanisms to keep developing plant tissue inaccessible to deer. In the second experiment we utilized the cull of Sitka black-tailed deer from two large islands (295 ha and 170 ha) to investigate the release of forest plant communities from deer browsing. Using a paired-island approach, deer were culled on two experimental islands but remained on three adjacent control islands. Clear increases in species richness and cover as well as changes in the community composition of the forest understorey of experimental islands in the five years following the initiation of culls suggested a quick return to the forest understorey communities thought to exist before deer modification. However, failure of key shrub species to establish, coupled with the development of closed canopy stands of Sitka spruce, Picea sitchensis, suggests possible alternate stable-states for some communities.