College of Behavioral & Social Sciences
Permanent URI for this communityhttp://hdl.handle.net/1903/8
The collections in this community comprise faculty research works, as well as graduate theses and dissertations..
Browse
5 results
Search Results
Item LONG-TERM IMPACTS OF AMAZON FOREST DEGRADATION ON CARBON STOCKS AND ANIMAL COMMUNITIES: COMBINING SOUND, STRUCTURE, AND SATELLITE DATA(2020) Rappaport, Danielle I; Dubayah, Ralph; Morton, Douglas; Geography; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The Amazon forest plays a vital role in the Earth system, yet forest degradation from logging and fire jeopardizes carbon storage and biodiversity conservation along the deforestation frontier. Polices to reduce forest carbon emissions (REDD+) will fall short of their intended goals unless carbon and biodiversity losses from forest degradation can be monitored over time. Emerging remote sensing tools, lidar and ecoacoustics, provide a means to monitor carbon and biodiversity across spatial, temporal, and taxonomic scales to address data gaps on species distributions and time-scales for recovery. This dissertation draws from a novel multi-sensor perspective to characterize the long-term ecological legacy of Amazon forest degradation across a 20,000 km2 landscape in Mato Grosso, Brazil. It combines high-density airborne lidar, 1100 hours of acoustic surveys, and annual time series of Landsat data to pursue three complementary studies. Chapter 2 establishes the bedrock of the investigation by using fine-scale measurements of structure sampled across a large diversity of degraded forests to model the initial loss and time-dependent recovery of carbon stocks and habitat structure following fire and logging. Chapter 3 models the interactions between sound and structure to predict acoustic community variation, and to account for attenuation in dense tropical forests. Lastly, Chapter 4 uses sound to go beyond structure to identify the specific degradation sequences and pseudo-taxa that give rise to variation in the ‘acoustic guild’ over time. Soundscapes reveal strong and sustained shifts in insect assemblages following fire, and a decoupling of biotic and biomass recovery following logging that defy theoretical predictions (Acoustic Niche Hypothesis). The synergies between lidar and acoustic data confirm the long-term legacy of forest degradation on both forest structure and animal communities in frontier Amazon forests. After multiple fires, forests become carbon-poor, habitats become simplified, and animal communication networks became quieter, less connected, and more homogenous. The combined results quantify large potential benefits to protecting already-burned Amazon forests from recurrent fires. This dissertation paves the way for greater integration of remote sensing and analysis tools to enhance capabilities for bringing biomass and biodiversity monitoring to scale. Building on this research with species-level and multi-temporal measurements will reduce uncertainty around the breakpoints that drive carbon and biodiversity loss following degradation.Item Evaluating characterization of fire extent and fire spread in boreal and tundra fires of Alaska from coarse and moderate resolution MODIS and VIIRS data(2017-04-04) Loboda, Tatiana; O'Neal, Kelley; Yang, QiSatellite observations of fire occurrence, extent, and spread have become a routine source of information for fire scientists and managers worldwide. In remote regions of arctic and boreal zones, satellite observations frequently represent the primary and at times the only source of information about fire occurrence. While a large suite of observations have been shown to provide beneficial and important information about fire occurrence, coarse and moderate resolution data from polar orbiting satellites in optical and thermal ranges of the electromagnetic spectrum provide the most widely-used observations that characterize on-going burning processes and consistent estimates of fire-affected areas. The reliance of the global community on active fire detections and burned area estimates delivered from the Moderate Resolution Imaging Spectroradiometer (MODIS) raises concerns about the continuity of the data record beyond the lifetime of this mission. The Visible Infrared Imaging Radiometer Suite (VIIRS) operated by National Oceanic and Atmospheric Administration (NOAA) represents the future of satellite fire monitoring within US-designed and operated missions. While some advancements have been introduced into the VIIRS fire detection capabilities, including enhanced spatial resolution of spectral bands aimed at active fire detection, the reduced number of orbital overpasses (only one VIIRS instrument is currently in orbit compared to two MODIS instruments) and other differences in data acquisition open the potential for substantial differences in future fire monitoring and mapping capacity and long-term record compatibility between MODIS and VIIRS observations. This study aims to assess and quantify the differences in characterization of on-going burning processes (including in time of detection, spatial fidelity and extent of fire detection coverage, fire spread rate, and fire radiative power) and post-fire extent within fire events (i.e. burned area mapping) in boreal forests and tundra regions of North America delivered by the MODIS Terra and Aqua collection 6 and VIIRS 750m and 375m active fire products and derived burned area maps. Since VIIRS standard data suite does not include burned area estimates, we used VIIRS and MODIS collection 6 surface reflectance products to generate an annual burned area record using the Regionally Adapted Burned Area algorithm developed specifically for high northern latitudes. Our initial results indicate that despite higher spatial resolution of VIIRS observations, the MODIS record (even from a single satellite) delivers a more comprehensive coverage of on-going burning within the large fire events of the 2014 fire season in the Northwest Territories, Canada. However, while substantial differences in fire characterization exist between the satellite data, there is strong potential for calibration of the data records (particularly for the burned area and fire radiative power estimates) for the two instruments necessary to achieve a consistent long-term record of fire occurrence in the high northern latitudes that would support long-term scientific studies and management decision-making processes.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 Contemporary Forest Cover Dynamics in Myanmar(2016) Biswas, Sumalika; Justice, Christopher O.; Vadrevu, Krishna P.; Geography; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Understanding forest cover dynamics is important for a nation’s environmental, social and political commitments. In the past decade, Myanmar had the highest deforestation rate, in mainland South East Asia (Hansen et al., 2013). Further, in 2009, Myanmar embarked on a landmark political change from military regime to democratic transition which significantly impacted its forest cover. Myanmar also ranks first with respect to forest fires in South/Southeast Asia. In Myanmar, forest cover loss and fire are intrinsically linked through the traditional taungya system of slash and burn. Thus, quantifying factors controlling forest fires in Myanmar is an important topic that needs attention. Although the Myanmar government established protected areas throughout the country to conserve forests, their effectiveness remains unevaluated. This dissertation aims to understand the current status of forest cover dynamics in Myanmar. The five chapters in this dissertation address the impact of the political transition on forest cover loss and fragmentation, fire disturbance in tropical evergreen and deciduous forests including the factors controlling vegetation fires in the protected and non-protected forests. The dissertation contributes to the existing knowledge in land cover and land use change science (LCLUC), ii especially the impact of institutional changes on forest cover in the tropics. The analysis of the relationship between forest loss, fire and effectiveness of the protected areas addressed in the study, contributes to regional knowledge on fire and conservation science respectively. The findings of this dissertation depict that in Myanmar, the political transition to democracy significantly influenced its forest cover. Our analysis showed that during 2001-2014, a total loss of 2,030,101 ha of forest occurred at the rate of 145,007.21 ha/year with a linear increase of 15,359 (±1793) ha/year. The observed increase in variance in between 2008-2011 coincides with political transition period which started with the formation of the new Constitution in 2008 and ended with the military government handing over power to the democratic government in 2011. Analysis of trend and variance patterns of two landscape fragmentation metrics (Number of Patches and Mean Patch Area) at the provincial level show the influence of the political transition on landscape fragmentation. The impact of political transition was more pronounced in provinces associated with plantations and urban areas. Among the rubber producing States, the border States, Shan, Kayah, and Kayin were more impacted compared to inland Mon. Tanintharyi and Bago Regions showed higher variance in residuals of both metrics before the transition occurred due to the military government supported oil palm and teak plantations. Fragmentation and the variance in fragmentation metrics in Kachin increased post 2008. Apart from plantation areas, urban areas like Yangon and Mandalay showed high fragmentation post 2009 period after the new government was formed. We attribute the forest loss and fragmentation to the economic and structural reforms of the democratic government, specifically to the increased granting of agricultural concessions and logging for plantations. iii A study of the fire regime from 2003 to 2012 using MODIS satellite data suggested March as the peak of the fire season with 12900 km2 of Burned Area (BA) and 95000 fire counts. Forests accounted for majority (41.3%) of the total BA and most fires (89.7%) resulted in medium or high vegetation disturbance. A higher negative correlation between BA and Gross Primary Productivity (GPP) was reported for deciduous forests than for evergreen forests (r=0.49 vs r = 0.36, p ~ 0). A maximum decrease in 29% of original GPP (2007-2012) was observed in the evergreen forest patches. The scale-dependent correlation analysis suggested significant BA-GPP correlation at 1 × 1 degree, as compared to finer resolutions. These results highlight the significance of fires impacting carbon cycle. An in-depth analysis of fire causative factors in Myanmar was studied. The mean fire density in non-protected areas was found to be two times more than in protected areas. Fire-land cover partition analysis suggested dominant fire occurrences in the savannas (protected areas) and woody savannas (non-protected areas). The five major fire causative factors in protected areas in descending order were found to be population density, land cover, tree cover percent, travel time from nearest city and temperature. The causative factors in non-protected areas were population density, tree cover percent, travel time from nearest city, temperature and elevation. The fire susceptibility analysis showed distinct spatial patterns with central Myanmar as a hot spot region of vegetation fires. Results from propensity score matching suggested that forests within protected areas have 11% less fires than non-protected areas. These findings provide information to policy makers about the current forest loss, forest fragmentation and forest fire hotspots, status of forest conservation and can be used to inform, update or evaluate policies. These findings are timely and can guide policy makers to arrive at best management strategies as the new government is formulating policies and laws and amending old ones to aid forest conservation.Item Carbon Sequestration and Agents of Woody Encroachment in Southeastern Arizona Semi-arid Grasslands(2014) O'Neal, Kelley; Justice, Christopher; Geography; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Woody encroachment and proliferation within dryland ecosystems is potentially the second largest portion of the North American carbon sink and one of the largest areas of uncertainty. This dissertation examines a semi-arid grassland located in southeastern Arizona to better understand woody encroachment, agents of change, and the resultant carbon storage from 1984-2008. The objectives were to quantify changes in woody cover, rank agent importance, estimate carbon density, and calculate voluntary market value. The first objective of mapping changes in woody cover was addressed using a Landsat time-series to measure woody cover and calculate the change, rate of change, and change relative to initial cover over the 25-year time period. Results show the change in woody cover varies spatially and ranges from approximately -2 to 11% with most areas experiencing a 5% increase and 92% relative increase over initial cover, indicating woody cover nearly doubled in the region. The second objective of ranking the importance of agents was achieved using an ensemble classifier. Agents examined included grazing, number of times burned, soil texture, soil productivity, elevation, slope, aspect, and initial woody cover. Initial woody cover, number of times burned, elevation, and grazing were ranked as the most important agents of woody encroachment, indicating the importance of historical land management and disturbance, frequent fire, topography and correlated precipitation, and land use. The third objective of producing carbon estimates and calculating economic opportunity in the voluntary carbon markets was accomplished by applying cover to biomass, root:shoot, and carbon equations to the final woody plant cover maps to calculate carbon stocks, carbon density, and voluntary market value. Results show very low carbon density in the study area relative to similar ecosystems and other ecosystems in general. Given the insignificant annual accumulation of carbon on the small ownership parcels, current low carbon trading prices, and high beef prices, management for storage is not economically viable in the study area at this time.