UMD Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/3
New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a given thesis/dissertation in DRUM.
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Item FOREST CHANGE AND OIL PALM EXPANSION IN INDONESIA: BIOPHYSICAL AND SOCIOECONOMIC ANALYSIS(2022) Xin, Yu; Sun, Laixiang; Geography; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Palm oil is the world's most widely used edible oil, and Indonesia has been the largest producer since 2007 and now makes up around 58% of the global market. The oil palm production has benefited the economic growth and lifted the living standards of local people in Indonesia, but this gain is often at the cost of replacing tropical forest, destructing peatland, inducing greenhouse gas (GHG) emissions, and reducing biodiversity. The expansion of oil palm plantation in Indonesia is bound to increase as the global demands continue to grow. The challenge of meeting the increased demand for oil palm products while effectively protecting tropical forest and its ecosystem services is an important tradeoff issue for both scientists and policymakers. However, little is known on the expansion patterns of oil palm in Indonesia, especially the underlying drivers with temporal and spatial details. To effectively address the knowledge gaps and deal with the challenges, this dissertation aims to first characterize the historical patterns driven by the variations in the benefits and costs of oil palm expansion across space and over time. It then projects the possible future spatial patterns and estimates the potential loss of land with high environmental values in order to meet the future global demand for oil palm products. This dissertation consists of three principle essays. The first essay identifies the major land sources of oil palm expansion in Indonesia with temporal details, and reveals the joint role of biophysical and socioeconomic drivers in shaping the spatial patterns of oil palm expansion by employing spatial panel models at the regency level. The second essay focuses on the temporal dynamics of the biophysical and socioeconomic drivers and the timing of estate crop (mainly oil palm) expansion by using Cox proportional hazard models (CPHMs) and their extensions with time-variant effects at the 1km × 1km grid level. It also explores the role of land use and land cover change (LCLUC) trajectory hopping in estate crop expansion into natural forest by introducing multi-state survival analysis to land-use science. The third essay projects the export demand for oil palm products from Indonesia by 2050 under different global trade scenarios with generalized geo-economic gravity models, and quantifies the possible tradeoffs between oil palm expansion and environmental conservation by allocating the projected demand to 1km × 1km grids across Indonesia applying parametric survival analysis. This study indicates that oil palm expansion in Indonesia has been strongly stimulated by the export value of oil palm products and prefers land with good biophysical suitability and infrastructure accessibility. As land resources become more limited, the effects of socioeconomic factors decrease following the ‘pecking order’ sequence, and the plantation expands into remote but fertile areas with high conversion costs or legal barriers. The degraded land surpassed natural forest and became the major direct land source of oil palm expansion in recent years, but degraded land had increasingly served as a land banking mechanism and a clearing-up tactic. This LCLUC trajectory hopping mechanism has made the protected area (PA) designations and sustainable development requirements become less and less effective in protecting tropical natural forest. Lowland secondary forest and peatland are the high-environmental-value (HEV) areas with the highest risks of conversion to oil palm plantation. To cope with the LCLUC trajectory hopping mechanism, Indonesia needs to have well-designed and fully enforced policies which limit/ban expansion into protected areas, peatland conversion, and deforestation of both primary and secondary forest. The country also needs more effective economic compensation mechanisms to promote more environment-friendly oil palm plantation. In this way, it is possible for Indonesia to maintain its leading position in oil palm production and exportation, while enhancing its role in environmental protection, such as climate change mitigation and biodiversity conservation. This dissertation improves our understanding of oil palm expansion in Indonesia by integrating economic science theory, advanced econometric techniques, and the best available remote-sensing data. It adds to the existing literature on analyzing the impacts of human behaviors on LCLUC at various spatial and temporal scales, especially from a longitudinal perspective.Item QUANTIFYING VULNERABILITY OF PENINSULAR MALAYSIA’S TIGER LANDSCAPE TO FUTURE FOREST LOSS(2018) Shevade, Varada; Loboda, Tatiana V.; Geography; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Agricultural expansion has been the dominant driver of tropical deforestation and increased consumption of commodities and resulting global trade have become distal drivers of land cover change. Habitat loss and fragmentation threaten biodiversity globally. Peninsular Malaysia, particularly, has a long history of land cover land use change and expansion of plantations like those of oil palm (Elaeis guineensis). Deforestation and plantation expansion threaten the Malayan tiger (Panthera tigris jacksonii), a critically endangered subspecies of the tiger endemic to the Malay Peninsula. Conservation of tigers and their long-term viability requires not only the protection of habitat patches but also maintenance of corridors connecting habitat patches. The goal of this dissertation was to understand patterns of recent forest loss and conversions, determine the drivers of these changes, and model future forest loss and changes to landscape connectivity for tigers. Satellite remote sensing data were used to map and estimate the extent of forest loss and forest conversions to plantations within Peninsular Malaysia. Mapped forest conversions to industrial oil palm plantations were used to model the factors influencing such conversions and the constraints to recent and future conversions. Finally, the mapped forest loss was used to model the deforestation probability for the region and develop scenarios of future forest loss. This study indicates that despite the history of land cover change and an extensive area under plantations, natural forest loss has continued within Peninsular Malaysia with about half of the cleared forests being converted to plantations. Proximity to pre-existing oil palm plantations is the most important determinant of forest conversions to oil palm. Such conversions are increasingly in more marginal lands indicating that biophysical suitability alone cannot determine where future conversions might take place. Forest conversions to oil palm plantations within the region are more constrained by accessibility to infrastructure rather than biophysical suitability for oil palm. The projected patterns of loss indicate lowland forests along the southeastern coast and in the center of the Peninsula are most vulnerable to future loss. This projected loss will likely reduce the connectivity between forest patches further isolating tiger populations in the southern part of the Peninsula. This study demonstrates the continued pressure on Peninsular Malaysia’s forests, the potential impact of persistent deforestation on forest connectivity, and draws attention to the need for conservation and restoration of forest linkages to ensure viability of the remaining Malayan tiger population.Item LAND USE AND LAND COVER CHANGE AS A DRIVER OF ECOSYSTEM DEGRADATION ACROSS BIOMES(2016) Noojipady, Praveen; Prince, Stephen D; Geography; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The expansion and intensification of agricultural production in human-dominated landscapes threaten efforts to sustain natural ecosystems and maintain agricultural production in a changing climate. Long-term use of agricultural lands, combined with conversion of natural ecosystems for agricultural production, can rapidly degrade the health of remaining natural ecosystems. The fundamental goal of this dissertation was to assess the impacts of anthropogenic degradation on stocks and sequestration of carbon. Although degradation alters a range of ecosystem services, case studies of ecosystem degradation in this dissertation focus on reductions in vegetation productivity, carbon stocks, and the extent of natural forest cover as a result of human activity. Time series of satellite remote sensing data were used to track forest and rangeland degradation in the southwestern United States, forest carbon emissions from cropland expansion in the Brazilian Cerrado, and fire-driven forest conversion for oil palm plantations in Southeast Asia. Three major themes link the regional case studies: expansion and intensification of agricultural production, market demand and certification, and agricultural management in response to climate variability. Conclusions from the dissertation underscore the widespread influence of land management on vegetation productivity and forest carbon stocks. In the Southwest United States, reductions in net primary production on managed lands were higher in forested landscapes than other cover types. In contrast, Native American Indian Reservations, often considered to be more degraded, actually had smaller absolute reductions in net primary productivity during 2000-2011. Multi-year droughts in the southwest present new challenges for managing forests and rangelands, and climate projections suggest dry conditions will intensify in the coming century. In Southeast Asia, industry-led efforts to certify sustainable palm oil production were evaluated using satellite data on fires and forest loss. Rates of fire-driven deforestation and total fire activity declined following certification, highlighting the potential for certification to reduce ignitions during El Niño years and protect remaining fragments of lowland and peat forest. Aligning certification criteria for sustainable palm oil with satellite monitoring capabilities may help accelerate compliance with environmental legislation and market demands for deforestation-free products. In Brazil, government and industry actions to limit Amazon deforestation have largely overlooked the neighboring Cerrado biome. Forest carbon emissions from deforestation for soy expansion in the Cerrado increased substantially after the implementation of the Soy Moratorium in the Brazilian Amazon, partially offsetting recent reductions in Amazon deforestation carbon emissions. The success of policies to support sustainable agricultural production therefore depends on efforts to minimize cross-biome leakage and the ability to monitor compliance and unintended consequences. Solutions for management must also confront the growing influence of climate variability. Time series of satellite data may allow early detection of degradation impacts and support efforts to mitigate the influence of sustained agricultural production on natural systems. Changes in vegetation carbon stocks from ecosystem degradation varied across case studies, underscoring the diverse nature of direct and indirect drivers of degradation across different land use systems. Direct human drivers of ecosystem degradation in the southwest United States from management of livestock grazing resulted in gradual changes in vegetation productivity, whereas mining and oil extraction areas showed large and permanent reductions. Forest carbon emissions from agriculture expansion in the Cerrado were a one-time process, as native vegetation is cleared for cropland expansion. In contrast, the carbon emissions from Southeast Asia’s forest and peatland conversion involve both sudden and gradual processes, as carbon accumulation in oil palm plantations partially compensates for emissions from forest conversion. Overall, this research made contributions to understanding of the regional impacts of human activity and the potential for climate change mitigation from sustainable land use practices in human-dominated landscapes.Item Genetic diversity and persistence of mayfly populations in disturbed headwater streams(2007-04-25) Alexander, Laurie Constance; Lamp, William O.; Hawthorne, David J.; Entomology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Movements of individuals shape the spatial structure of populations and play an important role in their persistence. For aquatic insects with winged adult stages, properties of the terrestrial landscape influence in-stream habitat quality and, in naturally patchy habitats such as dendritic stream networks, connectivity among habitat patches. Connectivity here refers to the population dynamics dependent on migration and gene flow among insect populations in semi-isolated stream segments. When populations are spatially connected, effects of local disturbance (e.g., habitat loss or degradation) can have a ripple effect, ultimately altering regional processes that reflect back to the local patch. But since regional and local population dynamics occur at different rates, detrimental effects of local disturbance are often not detected by biomonitoring efforts at the patch level until they have rippled through regional processes, by which time large-scale population extinction risk may have become unacceptably high. My dissertation examines the effect of local and regional disturbance on the population density, genetic structure, genetic diversity, and persistence of mayfly populations living in forested and deforested headwater streams in the Central Piedmont region of Maryland and Virginia. I sampled populations of the mayfly Ephemerella invaria (Walker) in 24 first-order streams across 9 headwater stream networks. The sampling period (2001-2004) spanned a regional drought during which some of the streams went dry. Thus I was able to look at the interaction of local deforestation and stochastic regional disturbance in my study system. In summary, my results indicate that in these mayfly populations: 1. Historically, long-range dispersal of Ephemerella occurred at levels sufficient to maintain gene flow across major watersheds, indicating excellent passive or active dispersal capability in these insects. 2. Deforestation of small watersheds decreases the rate of stream re-colonization and the recovery of prior population densities following a major disturbance. 3. Deforestation is correlated with loss of population genetic diversity. 4. Highly differentiated migrants represent a disproportionate share of the diversity in some mayfly populations. 5. Stochastic regional disturbance (e.g., drought) interacting with local disturbance (e.g., small scale watershed deforestation) can increase population extinction risk.Item Factors Affecting Agricultural Expansion in Forest Reserves of Thailand: The Role of Population and Roads(2006-04-27) Puri, Jyotsna; Cropper, Maureen L; Bockstael, Nancy; Agricultural and Resource Economics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)In this dissertation, I examine the role of population and transportation costs in determining agricultural expansion in 670 villages located in Forest Reserves of Thailand, over the period 1986-1996. Specifically, I examine the role of population and transportation costs as drivers of agricultural decisions regarding crop adoption and area planted, and in determining the intensity of cultivation and agricultural expansion. I also contrast the impact of these variables on two groups of villages in Forest Reserves - villages whose residents 'have no secure property rights' and those whose 'land rights are ambiguous'. I examine Feder et al.'s (1988) conclusions about the importance of property rights in Thai forest reserves and find that there is some evidence supporting their conclusions in this study. Differences in property rights account for some difference in the agricultural decisions of the two groups of villages, but that the nature of data does not allow a sharper distinction. Results reported in the study are consistent with other studies of the area. The study suggests that decisions regarding crop adoption and crop area are sensitive to population but the magnitudes of impact are small. Lack of significance of transport costs in determining cropping decisions suggests that rural road building programs will not necessarily promote deforestation in the study area, contrary to evidence in other parts of the world. This is particularly important given the large number of Forest Reserve residents in Thailand, and the fact that, Forest Reserves are the last bastions of forests, and consequently of biodiversity, in Thailand. One policy implication of this is that investments in roads that help to increase access to markets and aid poverty alleviation may not have the deleterious effects on forests that would otherwise be expected.