Browsing by Author "Wu, Yi-Jei"

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    Forest Change Dynamics Across Levels of Urbanization in the Eastern US
    Wu, Yi-Jei (Virginia Tech, 2014-09-03)
    The forests of the eastern United States reflect complex and highly dynamic patterns of change. This thesis seeks to explore the highly variable nature of these changes and to develop techniques that will enable researchers to examine their temporal and spatial patterns. The objectives of this research are to: 1) determine whether the forest change dynamics in the eastern US differ across levels of the urban hierarchy; 2) identify and explore key micropolitan areas that deviate from anticipated trends in forest change; and 3) develop and apply techniques for Big Data exploration of Landsat satellite images for forest cover analysis over large regions. Results demonstrate that forest change at the micropolitan level of urbanization differs from rural and metropolitan forest dynamics. The work highlights the dynamic nature of forest change within the Piedmont Atlantic megaregion, largely attributed to the forestry industry. This is by far the most dominant change phenomenon in the region but is not necessarily indicative of permanent forest change. A longer temporal analysis may be required to separate the contribution of the forest industry from permanent forest conversion in the region. Techniques utilized in this work suggest that emerging tools that provide supercomputing/parallel processing capabilities for the analysis of big satellite data open the door for researchers to better address different landscape signals and to investigate large regions at a high temporal and spatial resolution. The opportunity now exists to conduct initial assessments regarding spatio-temporal land cover trends in the southeast in a manner previously not possible.
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    Investigating Forest Conversion Across Several Scales of Urbanization in the Eastern United States
    Wu, Yi-Jei; Thomas, Valerie A.; Oliver, Robert D. (2014)
    Urbanization in the United States has clearly impacted land cover, and land use and land cover change (LULCC) patterns. A great body of literature has addressed the negative results of increased sprawl and a supporting literature has catalogued the story of forest loss—to grassland/ shrub, to agricultural land, to developed land and other land use categories. The Micropolitan Statistical Area (μSA) is a new geographic entity created in 2003 by the Office of Management and Budget (OMB) to depict the transitional area between Metropolitan Statistics Areas (MSAs) and non-designated areas (i.e., rural regions). Our prior work has demonstrated that μSAs are unique with regards to the dynamics of land conversion for development, and that there is a clear need to investigate the regional drivers of specific types of land-cover change at this scale. This research seeks to (1) tabulate the amount difference of forest conversion among MSAs, μSAs, and non-designated areas in select megaregions; and (2) highlight/ depict the change in key μSAs (computed as a percentage of forest cover change) across east coast. By combining μSA boundaries with the National Land Cover Database (NLCD) change product and change detection results from Google Earth Engine platform to examine forest cover change patterns across four East-Coast megaregions (as defined by America 2050 [Florida, Piedmont Atlantic, Great Lakes and the North East megaregion]). We have an opportunity to illustrate that in rare circumstances there are μSAs that have witnessed an irregularities in forest conversion between 2001 and 2006.