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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
481

Medžiojamosios faunos būklė Praviršulio- Tyrelio botaniniame- zoologiniame draustinyje / Condition of hunting fauna in zoological reservation of Praviršulio- Tyrelio

Jasaitis, Marius 08 June 2005 (has links)
Research of possibility to sustain both hunting fauna and forrest in reservation.
482

Effects of forestry on stream water chemistry during autumn : A before and after comparison between a reference and two streams with clear-cut watershed areas

Linda, Engström January 2013 (has links)
Forestry is a large-scale business in many countries, and in northern Sweden a large portion of the Boreal forests is cut. Yet very few studies have investigated the impacts of forestry on the vast number of receiving stream waters. This study has therefore investigated the impacts of forestry, through clear-cutting, on stream water chemistry during autumn conditions in northern Sweden. The study compares the parameters water height, absorbance, dissolved organic carbon, total dissolved nitrogen and total phosphorus in two inlet streams in recently deforested sites, <1 year ago, and an undisturbed reference inlet stream. The disturbed inlet streams are compared to the reference inlet stream the year before and after clear-cutting. This study shows that during a 15- day period from late August to the beginning of September, water height was increased in both disturbed inlet streams, indicative of a higher run-off post-harvest. Absorbance showed a large decrease post-harvest in the disturbed inlet streams. Total dissolved nitrogen and total phosphorus concentrations decreased slightly after clear-cut in both disturbed inlet streams. The effect was probably larger for phosphorus, since the seasonal variation in the reference was larger in 2013. DOC concentrations increased slightly in one of the disturbed inlet streams in 2013, but decreased slightly in the other disturbed inlet stream. The increased run-off was therefore not followed by a higher DOC and nutrient leakage. Results suggest that during a short period in the autumn, harvest does not seem to lead to increased DOC and nutrient losses to receiving stream waters.
483

A STOCHASTIC DYNAMIC PROGRAMMING APPROACH FOR OPTIMIZING MIXED-SPECIES FOREST STAND MANAGEMENT POLICIES

Comeau, Jules 10 February 2011 (has links)
The main goal is to develop decision policies for individual forest stand management. It addresses three major areas of interest in the optimal management of individual forest stands: incorporating a two-species growth and yield model into a single stand management model, incorporating a comprehensive list of management options into a single stand management model, and incorporating uncertainty into a single stand management model. Dynamic programming (DP) is a natural framework to study forest management with uncertainty. The forest stand management problem, as modelled in this thesis, has a large dimensional state space with a mix of discrete and continuous state variables. The DP model used to study this problem is solved by value iteration with the objective of understanding infinite horizon policies. However, since some of the state variables are continuous, all states can’t be examined in an attempt to create the cost-to-go function. Therefore, the cost-to-go function value is calculated at a given stage of the algorithm at a finite set of state points and then the cost-to-go values are approximated on the continuous portion of the state space using a continuous function. All of this is done with random processes impacting state transitions. With the mixed-species growth model developed in this thesis, a comprehensive list of management options can be incorporated into the DP model and, with the addition of uncertainty from sources such as market prices and natural disasters, near optimal stand management policies are developed. Solving the DP model with the required level of detail lead to the development of insight into function fitting on continuous state spaces and to the development of cost-to-go function approximation bounds. Studying the policies shows that the addition of uncertainty to the model captures the dynamics between market prices and stand definitions, and leads to policies that are better suited to decision making in a stochastic environment, when compared with policies that are developed with a deterministic model. Enough precision is built into the DP model to give answers to typical questions forest managers would ask.
484

Montana Logging Costs: Resources for Continued Industry Viability

Meek, Joshua P 10 February 2014 (has links)
Montanas logging industry has changed significantly over the past two decades. Increased operating costs and subsequent diminishing returns, combined with a shifting paradigm in regards to active forest management have had significant impacts on the economic and demographic make-up of the industry. One way to address these changes and mitigate the associated challenges of continued viability is through analysis of the factors and constraints impacting routine operational costs. Two methods were employed to estimate regional logging costs and changes over time. First, to provide a resource for comparison between commonly-utilized logging equipment, the hourly owning and operating costs of select mechanical, ground-based machines were calculated using the machine rate method from data supplied by western Montana equipment dealers. Second, an expert opinion survey of Montana and Idaho loggers was conducted, asking respondents to provide a simulated bid for a harvest unit typical of this region. The results from each method were compared to historic cost data, and reasons for increased logging expense were studied and discussed for fixed and variable cost categories, as were the impacts of changing operating conditions on costs. Results from the machine rate analysis suggest that inflation-adjusted operating costs for ground-based equipment are 47-93% higher than 20 years ago. Expert opinion survey results suggest that though costs are increasing, loggers are bidding at levels lower than actual costs merely to stay in business. Research on the reasons for these increases showed that costs have increased across certain fixed and variable categories, namely in equipment purchase price, fuel, labor wages and benefits, and repair/maintenance expense. Further, the number of operational days per year has decreased, administrative costs have increased, and there is increasing concern over volatile market conditions and the uncertainty over guaranteed future work. Clearly, this situation should be of considerable concern to those interested in retaining this sector in Montana. Vigilant consideration of operating costs and productivity will become increasingly critical to maintaining current infrastructure and helping to ensure the future of active forest management in Montana.
485

Territorial behaviour of prairie pothole blue-winged teal

Stewart, Gary R. January 1977 (has links)
No description available.
486

Comparative ecology of Quebec boreal forest : compositional, environmental and climatic models.

Bellefleur, Pierre January 1972 (has links)
No description available.
487

Montana Logging Costs: Resources for Continued Industry Viability

Meek, Joshua Padraic 07 February 2014 (has links)
Montanas logging industry has changed significantly over the past two decades. Increased operating costs and subsequent diminishing returns, combined with a shifting paradigm in regards to active forest management have had significant impacts on the economic and demographic make-up of the industry. One way to address these changes and mitigate the associated challenges of continued viability is through analysis of the factors and constraints impacting routine operational costs. Two methods were employed to estimate regional logging costs and changes over time. First, to provide a resource for comparison between commonly-utilized logging equipment, the hourly owning and operating costs of select mechanical, ground-based machines were calculated using the machine rate method from data supplied by western Montana equipment dealers. Second, an expert opinion survey of Montana and Idaho loggers was conducted, asking respondents to provide a simulated bid for a harvest unit typical of this region. The results from each method were compared to historic cost data, and reasons for increased logging expense were studied and discussed for fixed and variable cost categories, as were the impacts of changing operating conditions on costs. Results from the machine rate analysis suggest that inflation-adjusted operating costs for ground-based equipment are 47-93% higher than 20 years ago. Expert opinion survey results suggest that though costs are increasing, loggers are bidding at levels lower than actual costs merely to stay in business. Research on the reasons for these increases showed that costs have increased across certain fixed and variable categories, namely in equipment purchase price, fuel, labor wages and benefits, and repair/maintenance expense. Further, the number of operational days per year has decreased, administrative costs have increased, and there is increasing concern over volatile market conditions and the uncertainty over guaranteed future work. Clearly, this situation should be of considerable concern to those interested in retaining this sector in Montana. Vigilant consideration of operating costs and productivity will become increasingly critical to maintaining current infrastructure and helping to ensure the future of active forest management in Montana.
488

Spatial Distribution and Quantification of Forest Treatment Residues for Bioenergy Production

Wells, Lucas A. 07 February 2014 (has links)
The availability and spatial distribution of forest treatment residues are prerequisites to supply chain development for bioenergy production. To accurately estimate potential residue quantities, data must be provided to simulate stand-level silviculture across the landscape of interest. However, biomass utilization assessments often consider broad regions where adequate data are not supplied. At present, these measures are addressed using strategic level assessments and broad-based management that may not be applicable to all areas of the landscape. This thesis introduces a new methodology for spatially describing stand-level treatment residue quantities based on detailed silvicultural prescriptions and site specific management. Using National Agricultural Imagery Program (NAIP) imagery, the forest is segmented into treatment units based on user defined size constraints. Using a remote sensing model based on NAIP imagery and Forest Inventory and Analysis plot data, these units are attributed with stand-level descriptions of basal area, tree density, above ground biomass, and quadratic mean diameter . The outputs are used to develop silvicultural prescriptions and estimate available treatment residues under three alternative management scenarios at a range of delivered prices per bone dried ton (bdt) to a nearby bioenergy facility in southwestern Colorado. Using a marginal cost approach where treatment costs were covered by merchantable yields, the breakeven delivered price of treatment residues in this study is $48.94 per bdt yielding 167,685 bdt following a 10 year management simulation at a 5,000 acre per year annual allowable treatment level.
489

Whitebarkpine Forest Restoration: Cultural Perspectives from Blackfoot Confederacy Members

Augare-Estey, Kodi Jae 07 February 2014 (has links)
Whitebark pine (WBP) is a keystone species on the brink of extinction, threatened by fire suppression, white pine blister rust, along with mountain pine beetle infestation and climate change. The Blackfoot Confederacy from the Northern Rockies region, as part of their traditional practices and Worldview, has long gathered the nutrient-rich seeds and cambium of whitebark pine as part of their subsistence. This paper demonstrates how the perspectives, indigenous intelligence and worldview of members of the Blackfoot Confederacy could inform and supplement western science and increase the probability of success in restoration efforts whitebark pine forest ecosystems. With Blackfoot Confederacy acculturation and cultural assimilation, their oral history of traditional practices have faded, and the wealth of traditional practices and indigenous intelligence about their natural world could fade away without it ever being adequately documented. Further efforts are necessary to identify and retrieve indigenous intelligence to provide better ecological understanding of whitebark pine forest ecosystems, to give greater acknowledgement of Indigenous ways of knowing, and to preserve the Blackfoot Confederacy and their cultural identity and integrity.
490

The impact of cattle grazing on aspen regeneration on crown lands in western Manitoba

Renton, Jeffrey 23 September 2010 (has links)
In North America there has been an increasing appreciation for the value of trembling aspen (Populus tremuloides Michx.) as a source of timber. Moreover, trembling aspen stands and the understory vegetation that they support also provide valuable forage for livestock and wildlife. Timber harvesting and cattle grazing are often done on the same area of land in western Manitoba, though not simultaneously. The purpose of this project is to summarize the effects cattle grazing has on regeneration numbers and forest health in post-harvest aspen stands in the Aspen Parkland of western Manitoba.

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