China's forest product imports have surged over the past two decades, fueled by robust economic growth and an inadequate domestic timber supply. In 2017, China implemented a complete logging ban in its natural forests, further widening the domestic timber supply gap. Many observers highlight the large and expanding trade volume as a significant driver of deforestation and forest degradation, especially in tropical regions. This research investigates the relationship between China's imports of wood-based forest products and tropical forest loss (deforestation), as well as the impacts of China's complete logging ban in natural forests in shaping this relationship. I found that the logging ban has contributed China's timber imports from both provincial-level and supplying countries' analyses. However, economic development, wood products exports, and forest endowment have also played important roles. I found a positive relationship between China's imports of wood-based forest products and the forest loss across all tropical countries, except in Latin America. Additionally, land conversion to agricultural production and pasture for livestock, and rural population are important drivers of the tropical forest loss. The analysis results provide insight into the complex policy, environmental, and economic factors influencing China's imports and tropical forest loss. This research offers valuable guidance for the Chinese government in crafting balanced policies that protect domestic forests while addressing tropical deforestation. / Doctor of Philosophy / For more than 20 years, China's demand for wood products has grown fast, driven by rapid economic growth and the country's limited timber supply. To protect its forests and environment, China banned tree cutting in its natural forests in 2017, further increasing the need for imported timber. This growing demand has been blamed to link to forest loss, especially in tropical areas. This study looks at the connection between China's wood imports and the loss of tropical forests. It also examines how the tree cutting ban in China has impacted this relationship. The findings show that the ban has led to an increase in timber imports. However, economic growth, wood products exports, and the availability of forests in China are also important factors. The study found that China's wood products imports are associated with forest loss in most tropical regions, except for Latin America. Additionally, converting land use from forests to crop production and raising livestock, and population growth in rural areas are key drivers of forest loss. These results offer insights that can help the Chinese government makes policies to protect both domestic and tropical forests.

This study examines the effectiveness of using the Normalized Difference Vegetation Index (NDVI) derived from 1326 different Landsat Thematic Mapper and Enhanced Thematic Mapper images in finding isolated housing starts within the Commonwealth of Virginia's forests. Individual NDVI images were stacked by year for the years 1995-2011 and the yearly maximum for each pixel was extracted, resulting in a 17-year image stack of all yearly maxima (a 98.7% data reduction). Using location data from housing starts and well permits, known previously forested housing starts were isolated from all other forest disturbance types. Samples from housing starts and other forest disturbances, as well as from undisturbed forest, were used to derive vegetation index thresholds enabling separation of disturbed from undisturbed forest. Disturbances, once identified, were separated accurately (overall accuracy = 85.4 percent, F-statistic = 0.86) into housing starts and other forest disturbances using a classification tree and only two variables from the Disturbance Detection and Diagnostics (D3) algorithm: the maximum NDVI in the available recovery period and the slope between the NDVI value at the time of the disturbance and the maximum NDVI in the available recovery period. Landsat time series stacks thus show promise for identifying even the small changes associated with exurban development. / Master of Science / The objective of this study was to determine whether low-density development in previously forested areas can be identified using a time series of maximum annual vegetation greenness derived from the Landsat earth observing satellite missions. The study area was the Commonwealth of Virginia, USA. This study used 1326 different Landsat satellite images from the years 1995 through 2011. Each image contained over 34 million pixels, which were converted to a value between 0 and 1 that indicated how vegetated they were (a higher value being more vegetated). When houses are constructed trees are removed, thus lowering (at least temporarily) the overall greenness in a given area. Using location data from housing starts and well permits, known previously forested housing starts were isolated from all other forest disturbance types. Samples from housing starts and other forest disturbances, as well as from undisturbed forest, were used to develop greenness thresholds enabling separation of disturbed from undisturbed forest. Disturbances, once identified, were separated accurately (overall accuracy = 85.4 percent) into housing starts and other (non-housing) disturbances using a classification tree and the highest greenness a pixel attained in the available years after being disturbed (indicating how much vegetation returned in the recovery period) as well as the slope from the year of the identified disturbance to the year that had the highest value in the available recovery period.

Habitat fragmentation and biological invasions are widely considered to be the most significant threats to global biodiversity, and synergistic interactions between these processes have the potential to cause even greater biodiversity loss than either acting alone. The objective of my study was to investigate the effects of fragmentation on plant communities in native forest fragments, and to examine potential interactions between these effects and invasions by exotic plants at multiple spatial scales. I examined edge, area and landscape effects on plant invasions using empirical data from fragmented landscapes on the West Coast of New Zealand. My research revealed significant interactions between the amount of native forest cover in the landscape and the strength of edge and area effects on plant communities in forest fragments. The dominance of exotic plants in the community was highest at forest edges and decreased towards fragment interiors, however the interiors of very small fragments were relatively more invaded by exotic plants than those in larger fragments, reflecting a significant interaction between edge and area effects. Similarly, exotic dominance increased in more heavily deforested landscapes, but this effect was only apparent in very small fragments (<2 ha). The combined effects of small fragment size and low forest cover in the landscape appear to have promoted invasions of exotic plants in very small remnants. I explored the mechanisms underlying edge-mediated invasions in forest fragments and examined whether propagule availability and/or habitat suitability may be limiting invasions into fragments. Experimental addition of exotic plant propagules revealed that landscape forest cover interacted with edge effects on germination, growth and flowering rates of two short-lived, herbaceous species, and this appeared to be driven by elevated light and soil phosphorus levels at edges in heavily deforested landscapes. I also examined the role of traits in influencing plant responses to forest fragmentation. Different traits were associated with exotic invasiveness in edge and interior habitats of forest fragments, indicating that the traits promoting invasiveness were context dependent. Traits also had a major influence on responses of native plants to forest fragmentation, with generalist species appearing to benefit from fragmentation, as they can utilise both forest and open habitats, whereas native forest specialists have been negatively impacted by fragmentation.

Habitat fragmentation and biological invasions are widely considered to be the most significant threats to global biodiversity, and synergistic interactions between these processes have the potential to cause even greater biodiversity loss than either acting alone. The objective of my study was to investigate the effects of fragmentation on plant communities in native forest fragments, and to examine potential interactions between these effects and invasions by exotic plants at multiple spatial scales. I examined edge, area and landscape effects on plant invasions using empirical data from fragmented landscapes on the West Coast of New Zealand. My research revealed significant interactions between the amount of native forest cover in the landscape and the strength of edge and area effects on plant communities in forest fragments. The dominance of exotic plants in the community was highest at forest edges and decreased towards fragment interiors, however the interiors of very small fragments were relatively more invaded by exotic plants than those in larger fragments, reflecting a significant interaction between edge and area effects. Similarly, exotic dominance increased in more heavily deforested landscapes, but this effect was only apparent in very small fragments (<2 ha). The combined effects of small fragment size and low forest cover in the landscape appear to have promoted invasions of exotic plants in very small remnants. I explored the mechanisms underlying edge-mediated invasions in forest fragments and examined whether propagule availability and/or habitat suitability may be limiting invasions into fragments. Experimental addition of exotic plant propagules revealed that landscape forest cover interacted with edge effects on germination, growth and flowering rates of two short-lived, herbaceous species, and this appeared to be driven by elevated light and soil phosphorus levels at edges in heavily deforested landscapes. I also examined the role of traits in influencing plant responses to forest fragmentation. Different traits were associated with exotic invasiveness in edge and interior habitats of forest fragments, indicating that the traits promoting invasiveness were context dependent. Traits also had a major influence on responses of native plants to forest fragmentation, with generalist species appearing to benefit from fragmentation, as they can utilise both forest and open habitats, whereas native forest specialists have been negatively impacted by fragmentation.