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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.
181

The establishment and survival of native trees on degraded hillsides in Hong Kong

Hau, Chi-hang., 侯智恆. January 1999 (has links)
published_or_final_version / abstract / Ecology and Biodiversity / Doctoral / Doctor of Philosophy
182

Pagrindinių miško kirtimų projekto analizė Kuršėnų miškų urėdijos pavyzdžiu / The analysis of the project of the main deforestation as the example of Kursenai forestry

Matutis, Marijus 19 June 2006 (has links)
Matutis M. The analysis of the project of the main deforestation as the example of Kursenai forestry. Master’s work of forestry studies of forest economics/an adviser doc. A. Rutkauskas; LZUU, - Academy, 2006. – 96 p. 11 picture, 27 tables. Bibliography: 27 titles. SUMMARY In the master’s work there is reached the analysis of the project of the main deforestation as the example of Kursenai forestry. The object of the work: the wood of the forest groups of the state enterprise Kursenai forestry III (protective forests) and IV (economy forests). The objective of the work: to estimate the project of the main deforestation for the state enterprise Kursenai forestry during 1993 – 2005. The methods of the work: a) analysis; b) comparing; c) summation The methodic of the work: analysis of the documents, comparing of the indices and estimation of absolute and comparative volumes. The results of the work: the research was done and presented the main deforestation rates the most different were during 1994-1996, it increased even 25%, and the reason was the massive desiccation of the firs and the main rates of the deforestation were not adjusted. From 1997 the volume of truncated wood followed to the confirmed annual deforestation level, and from 1999 it exceeded in 0.3 thousand ktm. Or 0.5 %. And from 2002 there is strictly followed by the main deforestation rates. The keywords: the rate of the main deforestation; sub-economy, wood capacity, deflection.
183

Designing an incentive program to reduce on-farm deforestation in the East Usambara Mountains, Tanzania

Kaczan, David Unknown Date
No description available.
184

Spatial variation in soil organic carbon and stable carbon isotope signature in a pasture and a primary forest in central Panamá

Abraham, Muriel January 2004 (has links)
Soil properties and their spatial variability was measured to provide a strong database to assess the modification in soil properties associated with future changes in land use. Surface (0--10 cm) soil samples were collected from a 9 ha, 46-year-old pasture being converted to a native tree plantation and a neighboring control pasture near Sardinilla, Panama. A small-scale nested grid of surface soil samples was replicated in the future plantation and a primary forest in the region to evaluate the spatial variability of soil properties. Seven 1 m profiles were sampled in the future plantation and litter samples were collected at the forest and the future plantation. / Assuming the three sites were identical before the conversion to pasture, the difference in surface soil organic carbon (SOC) was 0.75 kg m-2 or equivalent to a loss of 0.017 kg m-2 yr -1 since the original land-use change. The control pasture is higher in bulk density but lower in percent SOC than the future plantation, which is critical to future comparisons. / The pasture soils showed signs of soil compaction and of the homogenization of soil properties. For the 7 profiles in the future plantation, total SOC mass ranged from 13.45 to 23.80 kg m-2, and stable isotopes revealed that 82% of the SOC in the top 10 cm is derived from the pasture vegetation, down to 23% at 1 m depth. / Spatially, the full scale of spatial variability was not determined from the nested grids alone. In addition, the 15 x 15 m grid in the future plantation generally over-estimated the semivariance at the scales below 3 m. The nested grids assessed the minimum measurable semivariance below 5 m. / The precision of surface estimations from point observations can be improved by adding a 5 x 5 m grid to any large-scale sampling scheme.
185

Community-based forest husbandry : a case study from Mozambique.

Singini, Paulo Juliao Tomás. January 2003 (has links)
Natural resource harvesting still plays an important role in the economy of southern Africa. In Mozambique, the continuous exploitation of the most valuable components of the indigenous woodlands in locations such as the Catuane Administrative Post in Matutuine District, have put pressure on the natural resources so that concern has motivated this research in order to guide such actions in support of sustainable use. This was a preliminary study, the intention being to establish: • what are the necessary environmental conditions for the sustainability of silviculture? • which species may be candidates for cultivation? • whether local people would support cultivation of trees for charcoal and woodfuel; and • what the attitude of government and non-government organizations was to tree cultivation.? The research approach taken in this study was qualitative, relying on interviews, reviewing literature and documentary analysis. Respondents were drawn from different categories such as the local communities of the study area, experts in silviculture, government officials and NGO employees. The study shows that environmental conditions are harsh and are not particularly favourable for the cultivation of trees. Nevertheless, a review of information on the requirements and properties of woody species indicates that there . are candidate species that could be considered for cultivation, but productivity is likely to be low. Although there is some support for cultivation of trees, motivation is weak and strong extension support will be required to achieve success. The findings show, however that whilst there is policy support it is not accompanied by support on the ground. It is suggested that this reflects failure to appreciate the value of co-operative management and suggestions are made as to how these can be improved. / Thesis (M.Env.Dev.)-University of Natal, Pietermaritzburg, 2003.
186

A 100-year retrospective and current carbon budget analysis for the Sooke Lake Watershed: Investigating the watershed-scale carbon implications of disturbance in the Capital Regional District’s water supply lands / One hundred-year retrospective and current carbon budget analysis for the Sooke Lake Watershed

Smiley, Byron 01 May 2015 (has links)
Northern forest ecosystems play an important role in global carbon (C) cycling and are considered to be a net C sink for atmospheric C (IPCC, 2007; Pan, et al., 2011). Reservoir creation is a common cause of deforestation and when coupled with persistent harvest activity that occurs in forest ecosystems, these disturbance events can significantly affect the C budget of a watershed. To understand the effects of these factors on carbon cycling at a landscape level, an examination of forest harvest and reservoir creation was carried out in the watershed of the Sooke Lake Reservoir, the primary water supply for the Greater Victoria area in British Columbia. Covering the period between 1910 and 2012, a detailed disturbance and forest cover dataset was generated for the Sooke Lake Watershed (SLW) and used as input into a spatially-explicit version of the Carbon Budget Model of the Canadian Forest Sector 3 (CBM-CFS3). The model was modified to include export of C out of the forest system in the form of dissolved organic C (DOC) into streams. The fraction of decaying C exported through this mechanism was tuned in the model using DOC measurements from three catchments within the SLW. Site-specific growth and yield curves were also generated for watershed forest stand types, in part, by using LiDAR-derived site indices. C transfers associated with disturbances were adjusted to reflect the disturbance types that occurred during the 100-year study period. Due to the removal of C resulting from wildfire, logging and residue burning, as well as deforestation disturbances, total ecosystem C stocks dropped from 700 metric tonnes of C per hectare (tC ha-1) in 1910 to their current (2012) level of ~550 tC ha-1 across the SLW. Assuming no change in management priorities and negligible effects of climate change, total ecosystem C stocks will not recover to 1910 levels until 2075. The cumulative effect of reservoir creation and expansion on the C budget resulted in 14 tC ha-1 less being sequestered (111,217 tC total) across the watershed by 2012. In contrast, sustained yield forestry within the Capital Regional District’s tenure accounts for a 93 tC ha-1 decrease by 2012, representing an impact six times greater than deforestation associated with reservoir creation. The proportionally greater impact of forestry activity is partly due to current C accounting rules (Intergovernmental Panel on Climate Change) that treats C removed from the forest in the form of Harvested Wood Products as C immediately released to the atmosphere as carbon dioxide. Cumulative DOC export to the Sooke Lake reservoir was ~30,660 tC by 2012, representing a substantial pathway for C leaving the forest ecosystem. However, more research is required to understand what fraction of terrestrially-derived DOC is sequestered long term in lake sediment. The results of this study will assist forest manager decision making on the appropriate management response to future forest disturbance patterns that could result from climate change and to improve climate change mitigation efforts. / Graduate / 0478 / 0425 / 0368 / byrons@uvic.ca
187

EFFECTS OF FOREST AND GRASS VEGETATION ON FLUVIOKARST HILLSLOPE HYDROLOGY, BOWMAN'S BEND, KENTUCKY

Martin, Linda Leann 01 January 2006 (has links)
Subsurface solutional pathways make limestone terrains sensitive to changes in soil properties that regulate flows to the epikarst. This study examines biogeomorphic factors responsible for changed water movements and erosion in fluviokarst slopes deforested 200 years ago along the Kentucky River, Kentucky. In this project, infiltration and water content data from forest and fescue grass soil profiles were analyzed within a detailed overview of system factors regulating hillslope hydrology. Results show that grass has growth and rooting characteristics that tend to create a larger volume of lateral water movement in upper soil layers than occurs under forests. This sets up the current emergent pattern of erosion in which water perches at grass slope bases and overwhelms pre-existing epikarst drainage. Tree roots are able to cause solution at multiple discrete points of entry into fractures and bedding planes, increasing storage capacity and releasing sediment over time. Grass roots do not enter bedrock, and their rooting depth limits diffuse vertical preferential flow in root channels to above one meter. In the areas dense clay soils, flow under grass is conducted sideways either through the regolith or at the bedrock surface. Rapid flow along rock faces in hillslope benches likely moves fines via subsurface routes from the hillslope shoulders, causing the exposure of flat outcrops under grass. Lower growing season evapotranspiration also promotes higher grass summer flow volumes. Gullying occurs at sensitive points where cutters pass from the uphill grassed area into the forest, or where flow across the bedrock surface crosses grass/forest boundaries oriented vertical to the slope. At these locations, loss of the protective grass root mat, coupled with instigation of tree root preferential flow in saturated soils, causes soil pipes to develop. Fluviokarst land management decisions should be based on site-specific slope, soil depth, and epkarst drainage conditions, since zones sensitive to erosion are formed by spatial and temporal conjunctions of a large number of lithologic, karst, soil, climate, and vegetation factors. This study shows that it is the composite of differing influences created by forest and grass that make forests critical for soil retention in high-energy limestone terrains.
188

Essays on the Evaluation of Environmental Programs

Hanauer, Merlin M 07 May 2011 (has links)
This dissertation comprises four chapters. The unifying theme is the evaluation of environmental programs. Specifically, each chapter examines some facet of the impacts of protected areas. The first chapter examines the heterogeneous environmental and economic impacts of protected areas in Costa Rica. Previous studies suggest that Costa Rica's protected area system induced both reduced deforestation and alleviated poverty. We demonstrate that these environmental and social impacts were spatially heterogeneous. Importantly, the characteristics associated with the most avoided deforestation are the characteristics associated with the least poverty alleviation. In other words, the same characteristics that have limited the conservation effectiveness of protected areas may have improved the social welfare impacts of these areas. These results suggest that `win-win' efforts to protect ecosystems and alleviate poverty may be possible when policymakers are satisfied with low levels of each outcome, but tradeoffs exist when more of either outcome is desired. The second chapter explores in more detail the heterogeneous impacts of protected areas in Costa Rica and Thailand. In particular we investigate the potential for protected areas to act as a mechanism for poverty traps and use semiparametric models to identify the spatial congruence of environmental and economic outcomes. We find no evidence that protected areas trap historically poorer areas in poverty. In fact, we find that poorer areas at baseline appear to have the greatest levels of poverty reduction as a result of protection. However, we do find that the spatial characteristics associated with the most poverty alleviation are not necessarily the characteristics associated with the most avoided deforestation. We demonstrate how an understanding of these spatially heterogeneous responses to protection can be used to generate suitability maps that identify locations in which both environmental and poverty alleviation goals are most likely to be achieved. In the third chapter we address the mechanisms through which protected areas affect economic outcomes. Using recently developed quasi-experimental methods and rich biophysical and demographic data, we quantify the causal post-treatment mechanism impacts of tourism, infrastructure development and ecosystem services on poverty, due to the establishment of protected areas in Costa Rica prior to 1980. We find that nearly 50% of the poverty reduction estimated in a previous study can be attributed to tourism. In addition, although the mechanism estimates for the infrastructure and ecosystem services proxies are negligible, we argue that the results provide evidence that enhanced ecosystem services from the establishment of protected areas has likely helped to reduce poverty. The results provide additional information to policy makers that wish to enhance the future establishment of protected areas with complementary policy. The final chapter studies the economic impacts of protected areas in Bolivia. We find that municipalities with at least 10% of their area occupied by a protected area between 1992 and 2000 exhibited differentially greater levels of poverty reduction between 1992 and 2001 compared to similar municipalities unaffected by protected areas. We find that the results are robust to a number of econometric specifications, spillover analyses and a placebo study. Although the overarching results that Bolivia's protected areas were associated with poverty reduction are similar to previous studies , the underlying results are subtly, but significantly, different. In previous studies it was found that controlling for key observable covariates lead to fundamentally antithetical results compared to naive estimates. Conversely, these results indicate that naive estimates lead to an over-estimation of the poverty reducing impacts of protected areas. The results expose the heterogeneity of protected area impacts across countries and, therefore, underscore the importance of country-level impact evaluations in order to build the global knowledge base regarding the socioeconomic impacts of protected areas.
189

Abundance patterns for vascular epiphytes in a tropical secondary forest, Costa Rica

Kull, Matthew Austin. January 2007 (has links)
Thesis (M.S.)--State University of New York at Binghamton, Department of Biological Sciences, 2007. / Includes bibliographical references.
190

Effects of land use changes on soil quality and native flora degradation and restoration in the highlands of Ethiopia : implications for sustainable land management /

Mulugeta Lemenih, January 2004 (has links) (PDF)
Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2004. / Härtill 5 uppsatser.

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