This page has only limited features, please log in for full access.
Accurate remote sensing of mountainous forest cover change is important for myriad social and ecological reasons, but is challenged by topographic and illumination conditions that can affect detection of forests. Several topographic illumination correction (TIC) approaches have been developed to mitigate these effects, but existing research has focused mostly on whether TIC improves forest cover classification accuracy and has usually found only marginal gains. However, the beneficial effects of TIC may go well beyond accuracy since TIC promises to improve detection of low illuminated forest cover and thereby normalize measurements of the amount, geographic distribution, and rate of forest cover change regardless of illumination. To assess the effects of TIC on the extent and geographic distribution of forest cover change, in addition to classification accuracy, we mapped forest cover across mountainous Nepal using a 25-year (1992–2016) gap-filled Landsat time series in two ways—with and without TIC (i.e., nonTIC)—and classified annual forest cover using a Random Forest classifier. We found that TIC modestly increased classifier accuracy and produced more conservative estimates of net forest cover change across Nepal (−5.2% from 1992–2016). TIC also resulted in a more even distribution of forest cover gain across Nepal with 3–5% more net gain and 4–6% more regenerated forest in the least illuminated regions. These results show that TIC helped to normalize forest cover change across varying illumination conditions with particular benefits for detecting mountainous forest cover gain. We encourage the use of TIC for satellite remote sensing detection of long-term mountainous forest cover change.
Jamon Van Den Hoek; Alexander Smith; Kaspar Hurni; Sumeet Saksena; Jefferson Fox. Shedding New Light on Mountainous Forest Growth: A Cross-Scale Evaluation of the Effects of Topographic Illumination Correction on 25 Years of Forest Cover Change across Nepal. Remote Sensing 2021, 13, 2131 .
AMA StyleJamon Van Den Hoek, Alexander Smith, Kaspar Hurni, Sumeet Saksena, Jefferson Fox. Shedding New Light on Mountainous Forest Growth: A Cross-Scale Evaluation of the Effects of Topographic Illumination Correction on 25 Years of Forest Cover Change across Nepal. Remote Sensing. 2021; 13 (11):2131.
Chicago/Turabian StyleJamon Van Den Hoek; Alexander Smith; Kaspar Hurni; Sumeet Saksena; Jefferson Fox. 2021. "Shedding New Light on Mountainous Forest Growth: A Cross-Scale Evaluation of the Effects of Topographic Illumination Correction on 25 Years of Forest Cover Change across Nepal." Remote Sensing 13, no. 11: 2131.
Recent concerns with pandemic outbreaks of human disease and their origins in animal populations have ignited concerns regarding connections between Emerging Infectious Diseases (EID) and development. As disasters, health, and infectious disease become part of planning concern (Matthew & McDonald, 2007), greater focus on household infrastructure and EID disease outbreaks among poultry is warranted. Following Spencer (2013), this study examines the relationship between the mix of household-scale water supplies, sanitation systems, and construction materials, and Highly Pathogenic Avian Influenza (HPAI) among poultry in a developing country: Vietnam. Findings of our multivariate logistic regressions suggest that a non-linear, Kuznets-shaped urban transition (Spencer, 2013) has an independent effect on the outbreak of HPAI, especially as it relates to household-level sanitation infrastructure. We conclude that the Kuznets-shape development of household infrastructure characteristics in Vietnam play a significant role in explaining where poultry outbreaks occur. Using secondary data from the Census of Population and Housing, and the Agricultural Census at the District and Commune levels for the country of Vietnam, we performed logistic regression to test the relationship between outbreaks of HPAI in poultry and newly-developed “coherence indices” (Spencer, 2013) of household water supply, sanitation, and construction materials that measure nonlinear, transitional development. Results show that district-scale coherence indices are negatively and independently correlated with HPAI outbreaks, especially for sanitation. Findings also suggest that community-scale coherence of urban infrastructures is a powerful tool for predicting where HPAI poultry outbreaks are likely to occur, thereby providing health planners new tools for efficient surveillance.
James H. Spencer; Melissa L. Finucane; Jefferson M. Fox; Sumeet Saksena; Nargis Sultana. Emerging infectious disease, the household built environment characteristics, and urban planning: Evidence on avian influenza in Vietnam. Landscape and Urban Planning 2019, 193, 103681 -103681.
AMA StyleJames H. Spencer, Melissa L. Finucane, Jefferson M. Fox, Sumeet Saksena, Nargis Sultana. Emerging infectious disease, the household built environment characteristics, and urban planning: Evidence on avian influenza in Vietnam. Landscape and Urban Planning. 2019; 193 ():103681-103681.
Chicago/Turabian StyleJames H. Spencer; Melissa L. Finucane; Jefferson M. Fox; Sumeet Saksena; Nargis Sultana. 2019. "Emerging infectious disease, the household built environment characteristics, and urban planning: Evidence on avian influenza in Vietnam." Landscape and Urban Planning 193, no. : 103681-103681.
The relationship between commuting distances and where people work has been studied for urban contexts in both developed countries and developing countries. However, few studies have examined the situation in rural areas, and none look at commuting distances to non‐farm workplaces in rural areas of developing countries. This paper investigates how commuting distance, and thus accessibility, to local non‐farm work influences non‐farm employment and out‐migration from rural villages in Northeast Thailand. The main issues examined are: (i) the distance that rural residents travel to work in local non‐farm jobs; and (ii) the influence that local non‐farm employment has on the number of outmigrants from rural villages. The study finds: (i) distance between villages and non‐farm work sites impact the number of villagers who are employed in regular wage work; (ii) beyond 20 km villagers are less likely to travel to non‐farm employment using their own means of transportation; and (iii) employment in regular wage work decreases outmigration. The findings from this study contribute to the debates over the drivers of rural out‐migration, rural livelihood changes, and agrarian changes that are taking place in Southeast Asia.
Yuko Shirai; Stephen Leisz; Jefferson Fox; A. Terry Rambo. Commuting distances to local non‐farm workplaces and out‐migration: The case of Northeast Thailand. Asia Pacific Viewpoint 2019, 60, 280 -295.
AMA StyleYuko Shirai, Stephen Leisz, Jefferson Fox, A. Terry Rambo. Commuting distances to local non‐farm workplaces and out‐migration: The case of Northeast Thailand. Asia Pacific Viewpoint. 2019; 60 (3):280-295.
Chicago/Turabian StyleYuko Shirai; Stephen Leisz; Jefferson Fox; A. Terry Rambo. 2019. "Commuting distances to local non‐farm workplaces and out‐migration: The case of Northeast Thailand." Asia Pacific Viewpoint 60, no. 3: 280-295.
In mountainous regions slope and aspect result in variations in the illumination condition and the same land cover type can therefore show differences in the reflectance depending on the orientation of the terrain slope towards the sun and the sensor of the satellite. Different topographic illumination correction methods exist and their performance varies depending on e.g. sun zenith and land cover type. Similarly a variety of evaluation criteria exist to assess the performance of the topographic correction methods and each evaluation criteria usually only considers certain aspects of the ability of the topographic correction method in reducing signal-to-noise. In this article we present a novel framework for the evaluation of topographically corrected image composites using cloud computing. We evaluated six topographic correction methods (Bin Tan, C-Correction, Minnaert with slope, Sun-Canopy-Sensor plus C-Correction, Statistical-Empirical, and Variable Empirical Coefficient Algorithm) in forest areas of four Landsat footprints in Nepal for a time series of image composites from 1988 to 2016. Our evaluation shows that the Statistical-Empirical topographic correction method provides the best overall performance, but in some years and footprints also other methods can show the best performance. We discuss these differences and related reasons in detail and give recommendations on the best use and evaluation of topographic correction methods.
Kaspar Hurni; Jamon Van Den Hoek; Jefferson Fox. Assessing the spatial, spectral, and temporal consistency of topographically corrected Landsat time series composites across the mountainous forests of Nepal. Remote Sensing of Environment 2019, 231, 111225 .
AMA StyleKaspar Hurni, Jamon Van Den Hoek, Jefferson Fox. Assessing the spatial, spectral, and temporal consistency of topographically corrected Landsat time series composites across the mountainous forests of Nepal. Remote Sensing of Environment. 2019; 231 ():111225.
Chicago/Turabian StyleKaspar Hurni; Jamon Van Den Hoek; Jefferson Fox. 2019. "Assessing the spatial, spectral, and temporal consistency of topographically corrected Landsat time series composites across the mountainous forests of Nepal." Remote Sensing of Environment 231, no. : 111225.
Since the early 2000s the Lao government has dramatically increased the number of large‐scale land concessions issued for agribusinesses. While studies have documented the social and environmental impacts of land dispossession, the role of Vietnamese labour on these Vietnamese‐owned rubber plantations has not previously been investigated. Taking a political ecology approach, we situate this study at the intersection between ‘land grabbing’ studies and work on ‘labour geographies’. Most of the remittances generated from Vietnamese working in Laos are used for non‐agricultural purposes, with people purposely choosing to not invest in agriculture in Vietnam. Vietnamese labour on Lao plantations still has significant spatial implications, both in Laos and in Vietnam, including through the norms, formal rules and practices introduced at rubber plantations by Vietnamese workers and management, but also through labour regime changes in Vietnam. In Laos, one of the most significant results has been to make certain spaces less welcoming to Lao labour. This study particularly points to the importance of geopolitics, as the close political relationship between Laos and Vietnam, and the fact that Vietnamese companies and managers are involved, is crucial for understanding the particular nature of the labour geographies associated with Vietnamese rubber plantations in Laos.
Ian G. Baird; William Noseworthy; Nghiem Phuong Tuyen; Le Thu Ha; Jefferson Fox. Land grabs and labour: Vietnamese workers on rubber plantations in southern Laos. Singapore Journal of Tropical Geography 2018, 40, 50 -70.
AMA StyleIan G. Baird, William Noseworthy, Nghiem Phuong Tuyen, Le Thu Ha, Jefferson Fox. Land grabs and labour: Vietnamese workers on rubber plantations in southern Laos. Singapore Journal of Tropical Geography. 2018; 40 (1):50-70.
Chicago/Turabian StyleIan G. Baird; William Noseworthy; Nghiem Phuong Tuyen; Le Thu Ha; Jefferson Fox. 2018. "Land grabs and labour: Vietnamese workers on rubber plantations in southern Laos." Singapore Journal of Tropical Geography 40, no. 1: 50-70.
This study investigated the implications of large-scale land concessions in the Red River Delta, Vietnam, and Northeast Cambodia with regard to urban and agricultural frontiers, agrarian transitions, migration, and places from which the migrant workers originated. Field interviews conducted near large-scale land concessions for industrial estates in the Red River Delta and rubber plantations in Northeast Cambodia suggest that these radically different concessions are paradoxically leading to similar reconfigurations of livelihoods, labor patterns, and landscapes despite basic differences in these forms of land use. Both the Red River Delta and Northeast Cambodia are frontier environments undergoing extensive agrarian change with migration to work in the large-scale land concessions leading to a shortage of farm labor that anticipates changes in farming practices and farm livelihoods. These population movements will lead to further land-use changes as governments invest in the infrastructure and services needed to support increased population density in the receiving areas. In addition, labor migrations associated with these investments affect land-use practices both at the site of the concession and the places from where the migrants originate.
Jefferson Fox; Tuyen Nghiem; Ham Kimkong; Kaspar Hurni; Ian G. Baird. Large-Scale Land Concessions, Migration, and Land Use: The Paradox of Industrial Estates in the Red River Delta of Vietnam and Rubber Plantations of Northeast Cambodia. Land 2018, 7, 77 .
AMA StyleJefferson Fox, Tuyen Nghiem, Ham Kimkong, Kaspar Hurni, Ian G. Baird. Large-Scale Land Concessions, Migration, and Land Use: The Paradox of Industrial Estates in the Red River Delta of Vietnam and Rubber Plantations of Northeast Cambodia. Land. 2018; 7 (2):77.
Chicago/Turabian StyleJefferson Fox; Tuyen Nghiem; Ham Kimkong; Kaspar Hurni; Ian G. Baird. 2018. "Large-Scale Land Concessions, Migration, and Land Use: The Paradox of Industrial Estates in the Red River Delta of Vietnam and Rubber Plantations of Northeast Cambodia." Land 7, no. 2: 77.
Over the past half century, countries of Mainland Southeast Asia (MSEA) – Cambodia, Laos, Myanmar, Thailand, and Vietnam – have witnessed increases in commercialized agriculture with rapid expansions of boom-crop plantations. We used MODIS EVI and SWIR time-series from 2001–2014 to classify tree-cover changes across MSEA and performed a supervised change detection using an upscaling approach by deriving samples from existing Landsat classifications. We used the random forest classifier and distinguished 24 classes (16 representing boom-crops) with an accuracy of 82.2%. Boom-crops occupy about 18% of the landscape (8% of which is rubber). Since 2003 74,960 km2 of rubber have been planted; 70% of rubber is planted on former forest land, and 30% on low vegetation area (mainly former croplands). Timing, patterns of change, and deforestation rates, however, differ among the MSEA countries and the high spatial and temporal detail of our classification allowed us to quantify dynamics and discuss political and socio-economic drivers of change.
Kaspar Hurni; Jefferson Fox. The expansion of tree-based boom crops in mainland Southeast Asia: 2001 to 2014. Journal of Land Use Science 2018, 13, 198 -219.
AMA StyleKaspar Hurni, Jefferson Fox. The expansion of tree-based boom crops in mainland Southeast Asia: 2001 to 2014. Journal of Land Use Science. 2018; 13 (1-2):198-219.
Chicago/Turabian StyleKaspar Hurni; Jefferson Fox. 2018. "The expansion of tree-based boom crops in mainland Southeast Asia: 2001 to 2014." Journal of Land Use Science 13, no. 1-2: 198-219.
Political and economic transitions have had substantial impacts on forest conservation. Where transitions are underway or anticipated, historical precedent and methods for systematically assessing future trends should be used to anticipate likely threats to forest conservation and design appropriate and prescient policy measures to counteract them. Myanmar is transitioning from an authoritarian, centralized state with a highly regulated economy to a more decentralized and economically liberal democracy and is working to end a long‐running civil war. With these transitions in mind, we used a horizon‐scanning approach to assess the 40 emerging issues most affecting Myanmar's forests, including internal conflict, land‐tenure insecurity, large‐scale agricultural development, demise of state timber enterprises, shortfalls in government revenue and capacity, and opening of new deforestation frontiers with new roads, mines, and hydroelectric dams. Averting these threats will require, for example, overhauling governance models, building capacity, improving infrastructure‐ and energy‐project planning, and reforming land‐tenure and environmental‐protection laws. Although challenges to conservation in Myanmar are daunting, the political transition offers an opportunity for conservationists and researchers to help shape a future that enhances Myanmar's social, economic, and environmental potential while learning and applying lessons from other countries. Our approach and results are relevant to other countries undergoing similar transitions.
Graham W. Prescott; William J. Sutherland; Daniel Aguirre; Matthew Baird; Vicky Bowman; Jake Brunner; Grant M. Connette; Martin Cosier; David Dapice; Jose Don T. De Alban; Alex Diment; Julia Fogerite; Jefferson Fox; Win Hlaing; Saw Htun; Jack Hurd; Katie LaJeunesse Connette; Felicia Lasmana; Cheng Ling Lim; Antony Lynam; Aye Chan Maung; Benjamin McCarron; John F McCarthy; William J. McShea; Frank Momberg; Myat Su Mon; Than Myint; Robert Oberndorf; Thaung Naing Oo; Jacob Phelps; Madhu Rao; Dietrich Schmidt-Vogt; Hugh Speechly; Oliver Springate-Baginski; Robert Steinmetz; Kirk Talbott; Maung Maung Than; Tint Lwin Thaung; Salai Cung Lian Thawng; Kyaw Min Thein; Shwe Thein; Robert Tizard; Tony Whitten; Guy Williams; Trevor Wilson; Kevin Woods; Alan D. Ziegler; Michal Zrust; Edward L. Webb. Political transition and emergent forest-conservation issues in Myanmar. Conservation Biology 2017, 31, 1257 -1270.
AMA StyleGraham W. Prescott, William J. Sutherland, Daniel Aguirre, Matthew Baird, Vicky Bowman, Jake Brunner, Grant M. Connette, Martin Cosier, David Dapice, Jose Don T. De Alban, Alex Diment, Julia Fogerite, Jefferson Fox, Win Hlaing, Saw Htun, Jack Hurd, Katie LaJeunesse Connette, Felicia Lasmana, Cheng Ling Lim, Antony Lynam, Aye Chan Maung, Benjamin McCarron, John F McCarthy, William J. McShea, Frank Momberg, Myat Su Mon, Than Myint, Robert Oberndorf, Thaung Naing Oo, Jacob Phelps, Madhu Rao, Dietrich Schmidt-Vogt, Hugh Speechly, Oliver Springate-Baginski, Robert Steinmetz, Kirk Talbott, Maung Maung Than, Tint Lwin Thaung, Salai Cung Lian Thawng, Kyaw Min Thein, Shwe Thein, Robert Tizard, Tony Whitten, Guy Williams, Trevor Wilson, Kevin Woods, Alan D. Ziegler, Michal Zrust, Edward L. Webb. Political transition and emergent forest-conservation issues in Myanmar. Conservation Biology. 2017; 31 (6):1257-1270.
Chicago/Turabian StyleGraham W. Prescott; William J. Sutherland; Daniel Aguirre; Matthew Baird; Vicky Bowman; Jake Brunner; Grant M. Connette; Martin Cosier; David Dapice; Jose Don T. De Alban; Alex Diment; Julia Fogerite; Jefferson Fox; Win Hlaing; Saw Htun; Jack Hurd; Katie LaJeunesse Connette; Felicia Lasmana; Cheng Ling Lim; Antony Lynam; Aye Chan Maung; Benjamin McCarron; John F McCarthy; William J. McShea; Frank Momberg; Myat Su Mon; Than Myint; Robert Oberndorf; Thaung Naing Oo; Jacob Phelps; Madhu Rao; Dietrich Schmidt-Vogt; Hugh Speechly; Oliver Springate-Baginski; Robert Steinmetz; Kirk Talbott; Maung Maung Than; Tint Lwin Thaung; Salai Cung Lian Thawng; Kyaw Min Thein; Shwe Thein; Robert Tizard; Tony Whitten; Guy Williams; Trevor Wilson; Kevin Woods; Alan D. Ziegler; Michal Zrust; Edward L. Webb. 2017. "Political transition and emergent forest-conservation issues in Myanmar." Conservation Biology 31, no. 6: 1257-1270.
Yuko Shirai; Jefferson Fox; Stephen J. Leisz; Hayao Fukui; A. Terry Rambo. The influence of local non-farm employment on rural household structure in Northeast Thailand. Journal of Rural Studies 2017, 54, 52 -59.
AMA StyleYuko Shirai, Jefferson Fox, Stephen J. Leisz, Hayao Fukui, A. Terry Rambo. The influence of local non-farm employment on rural household structure in Northeast Thailand. Journal of Rural Studies. 2017; 54 ():52-59.
Chicago/Turabian StyleYuko Shirai; Jefferson Fox; Stephen J. Leisz; Hayao Fukui; A. Terry Rambo. 2017. "The influence of local non-farm employment on rural household structure in Northeast Thailand." Journal of Rural Studies 54, no. : 52-59.
We performed a multi-date composite change detection technique using a dense-time stack of Landsat data to map land-use and land-cover change (LCLUC) in Mainland Southeast Asia (MSEA) with a focus on the expansion of boom crops, primarily tree crops. The supervised classification was performed using Support Vector Machines (SVM), which are supervised non-parametric statistical learning techniques. To select the most suitable SMV classifier and the related parameter settings, we used the training data and performed a two-dimensional grid search with a three-fold internal cross-validation. We worked in seven Landsat footprints and found the linear kernel to be the most suitable for all footprints, but the most suitable regularization parameter C varied across the footprints. We distinguished a total of 41 LCLUCs (13 to 31 classes per footprint) in very dynamic and heterogeneous landscapes. The approach proved useful for distinguishing subtle changes over time and to map a variety of land covers, tree crops, and transformations as long as sufficient training points could be collected for each class. While to date, this approach has only been applied to mapping urban extent and expansion, this study shows that it is also useful for mapping change in rural settings, especially when images from phenologically relevant acquisition dates are included.
Kaspar Hurni; Annemarie Schneider; Andreas Heinimann; Duong H. Nong; Jefferson Fox. Mapping the Expansion of Boom Crops in Mainland Southeast Asia Using Dense Time Stacks of Landsat Data. Remote Sensing 2017, 9, 320 .
AMA StyleKaspar Hurni, Annemarie Schneider, Andreas Heinimann, Duong H. Nong, Jefferson Fox. Mapping the Expansion of Boom Crops in Mainland Southeast Asia Using Dense Time Stacks of Landsat Data. Remote Sensing. 2017; 9 (4):320.
Chicago/Turabian StyleKaspar Hurni; Annemarie Schneider; Andreas Heinimann; Duong H. Nong; Jefferson Fox. 2017. "Mapping the Expansion of Boom Crops in Mainland Southeast Asia Using Dense Time Stacks of Landsat Data." Remote Sensing 9, no. 4: 320.
Highly pathogenic avian influenza (HPAI) is an important public health concern because of potential for widespread morbidity and mortality in humans and poultry and associated devastating economic losses. We examined how perceptions of the risk of HPAI in poultry vary across communes/wards in the north of Vietnam at different levels of urbanization (rural, peri-urban, urban). Analyses of questionnaire responses from 1081 poultry raisers suggested that the perceived risk of HPAI in poultry was highest in peri-urban and rural settings. We also found that perceived risk was higher when respondents rated settings in which they did not live and that the process of change is related to perceived risk. Compared with others, respondents in peri-urban areas reported less disease management planning; respondents in rural areas reported less ability to separate infected poultry. These findings are consistent with, and add to, the limited previous research on the perceived risk of HPAI in poultry in developing countries. What is new in the present findings is that we describe how urbanization is related to people's perceptions of and ability to respond appropriately to variations in their environment. In particular, the inability to respond is not necessarily because of an inability to perceive change. Rather, rapid and extensive change poses different challenges for poultry management as communes move from rural to peri-urban to urban settings. Our results suggest that health promotion campaigns should address the perceptions and needs of poultry raisers in different settings.
Melissa L. Finucane; Nghiem Tuyen; Sumeet Saksena; James H. Spencer; Jefferson M. Fox; Nguyen Lam; Trinh Dinh Thau; Tran Duc Vien; Nancy Davis Lewis. Perceived Risk of Avian Influenza and Urbanization in Northern Vietnam. EcoHealth 2017, 14, 144 -154.
AMA StyleMelissa L. Finucane, Nghiem Tuyen, Sumeet Saksena, James H. Spencer, Jefferson M. Fox, Nguyen Lam, Trinh Dinh Thau, Tran Duc Vien, Nancy Davis Lewis. Perceived Risk of Avian Influenza and Urbanization in Northern Vietnam. EcoHealth. 2017; 14 (1):144-154.
Chicago/Turabian StyleMelissa L. Finucane; Nghiem Tuyen; Sumeet Saksena; James H. Spencer; Jefferson M. Fox; Nguyen Lam; Trinh Dinh Thau; Tran Duc Vien; Nancy Davis Lewis. 2017. "Perceived Risk of Avian Influenza and Urbanization in Northern Vietnam." EcoHealth 14, no. 1: 144-154.
This paper follows forest conditions, agricultural practices, and livelihoods in a Nepali village between 1980 and 2010. A survey was administered to all village households in 1980, 1990 and 2010; semi-structured interviews were also conducted. Tree species frequency, density and dominance were determined for eight forest patches during each survey. Over this period the population of the village remained stable; the number of children decreased, and the number of people over 50 increased. Famers keep significantly fewer livestock, and have become less dependent on farming and more engaged in commercial activities. In 1980 the number of out-migrants was so few that they were not recorded; by 2010, 29 percent of the adult male population was engaged in migration. Nepal initiated an acclaimed Community Forestry program in the early 1990s; by 2010 about half the village’s forests showed improved tree density and size. Contrary to expectations and published literature, the study found that forest conditions in half of the village’s forests were not improved; and while livelihoods appeared to be better in 2010 than in 1980, they are not more secure as they are increasingly dependent on remittance incomes and hence at the whims of the international labor market.
Jefferson Fox. Community forestry, labor migration and agrarian change in a Nepali village: 1980 to 2010. The Journal of Peasant Studies 2016, 45, 610 -629.
AMA StyleJefferson Fox. Community forestry, labor migration and agrarian change in a Nepali village: 1980 to 2010. The Journal of Peasant Studies. 2016; 45 (3):610-629.
Chicago/Turabian StyleJefferson Fox. 2016. "Community forestry, labor migration and agrarian change in a Nepali village: 1980 to 2010." The Journal of Peasant Studies 45, no. 3: 610-629.
This study addresses the tradeoff between Vietnam’s national poultry vaccination program, which implemented an annual two-round HPAI H5N1 vaccination program for the entire geographical area of the Red River Delta during the period from 2005–2010, and an alternative vaccination program which would involve vaccination for every production cycle at the recommended poultry age in high risk areas within the Delta. The ex ante analysis framework was applied to identify the location of areas with high probability of HPAI H5N1 occurrence for the alternative vaccination program by using boosted regression trees (BRT) models, followed by weighted overlay operations. Cost-effectiveness of the vaccination programs was then estimated to measure the tradeoff between the past national poultry vaccination program and the alternative vaccination program. Ex ante analysis showed that the focus areas for the alternative vaccination program included 1137 communes, corresponding to 50.6% of total communes in the Delta, and located primarily in the coastal areas to the east and south of Hanoi. The cost-effectiveness analysis suggested that the alternative vaccination program would have been more successful in reducing the rate of disease occurrence and the total cost of vaccinations, as compared to the national poultry vaccination program.
Chinh C. Tran; John F. Yanagida; Sumeet Saksena; Jefferson Fox. An Alternative Vaccination Approach for The Prevention of Highly Pathogenic Avian Influenza Subtype H5N1 in The Red River Delta, Vietnam —A Geospatial-Based Cost-Effectiveness Analysis. Veterinary Sciences 2016, 3, 6 .
AMA StyleChinh C. Tran, John F. Yanagida, Sumeet Saksena, Jefferson Fox. An Alternative Vaccination Approach for The Prevention of Highly Pathogenic Avian Influenza Subtype H5N1 in The Red River Delta, Vietnam —A Geospatial-Based Cost-Effectiveness Analysis. Veterinary Sciences. 2016; 3 (1):6.
Chicago/Turabian StyleChinh C. Tran; John F. Yanagida; Sumeet Saksena; Jefferson Fox. 2016. "An Alternative Vaccination Approach for The Prevention of Highly Pathogenic Avian Influenza Subtype H5N1 in The Red River Delta, Vietnam —A Geospatial-Based Cost-Effectiveness Analysis." Veterinary Sciences 3, no. 1: 6.
To investigate the effects of expanding rubber (Hevea brasiliensis) cultivation on water cycling in Mainland Southeast Asia (MSEA), evapotranspiration (ET) was measured within rubber plantations at Bueng Kan, Thailand, and Kampong Cham, Cambodia. After energy closure adjustment, mean annual rubber ET was 1,211 and 1,459 mm yr−1 at the Thailand and Cambodia sites, respectively, higher than that of other tree-dominated land covers in the region, including tropical seasonal forest (812-1,140 mm yr−1), and savanna (538-1,060 mm yr−1). The mean proportion of net radiation used for ET by rubber (0.725) is similar to that of tropical rainforest (0.729) and much higher than that of tropical seasonal forest (0.595) and savanna (0.548). Plant area index (varies with leaf area changes), explains 88.2% and 73.1% of the variance in the ratio of latent energy flux (energy equivalent of ET) to potential latent energy flux (LE/LEpot) for midday rain-free periods at the Thailand and Cambodia sites, respectively. High annual rubber ET results from high late dry season water use, associated with rapid refoliation by this brevi-deciduous species, facilitated by tapping of deep soil water, and by very high wet season ET, a characteristic of deciduous trees. Spatially, mean annual rubber ET increases strongly with increasing net radiation (Rn) across the three available rubber plantation observation sites, unlike non-rubber tropical ecosystems, which reduce canopy conductance at high Rn sites. High water use by rubber raises concerns about potential effects of continued expansion of tree plantations on water and food security in MSEA. This article is protected by copyright. All rights reserved.
Thomas W. Giambelluca; Ryan G. Mudd; Wen Liu; Alan D. Ziegler; Nakako Kobayashi; Tomo'omi Kumagai; Yoshiyuki Miyazawa; Tiva Khan Lim; Maoyi Huang; Jefferson Fox; Song Yin; Sophea Veasna Mak; Poonpipope Kasemsap. Evapotranspiration of rubber (Hevea brasiliensis) cultivated at two plantation sites in Southeast Asia. Water Resources Research 2016, 52, 660 -679.
AMA StyleThomas W. Giambelluca, Ryan G. Mudd, Wen Liu, Alan D. Ziegler, Nakako Kobayashi, Tomo'omi Kumagai, Yoshiyuki Miyazawa, Tiva Khan Lim, Maoyi Huang, Jefferson Fox, Song Yin, Sophea Veasna Mak, Poonpipope Kasemsap. Evapotranspiration of rubber (Hevea brasiliensis) cultivated at two plantation sites in Southeast Asia. Water Resources Research. 2016; 52 (2):660-679.
Chicago/Turabian StyleThomas W. Giambelluca; Ryan G. Mudd; Wen Liu; Alan D. Ziegler; Nakako Kobayashi; Tomo'omi Kumagai; Yoshiyuki Miyazawa; Tiva Khan Lim; Maoyi Huang; Jefferson Fox; Song Yin; Sophea Veasna Mak; Poonpipope Kasemsap. 2016. "Evapotranspiration of rubber (Hevea brasiliensis) cultivated at two plantation sites in Southeast Asia." Water Resources Research 52, no. 2: 660-679.
In 1986, the Government of Vietnam implemented free market reforms known as Doi Moi (renovation) that provided private ownership of farms and companies, and encouraged deregulation and foreign investment. Since then, the economy of Vietnam has achieved rapid growth in agricultural and industrial production, construction and housing, and exports and foreign investments, each of which have resulted in momentous landscape transformations. One of the most evident changes is urbanization and an accompanying loss of agricultural lands and open spaces. These rapid changes pose enormous challenges for local populations as well as planning authorities. Accurate and timely data on changes in built-up urban environments are essential for supporting sound urban development. In this study, we applied the Support Vector Machine classification (SVM) to multi-temporal stacks of Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper Plus (ETM+) images from 1993 to 2010 to quantify changes in built-up areas. The SVM classification algorithm produced a highly accurate map of land cover change with an overall accuracy of 95%. The study showed that most urban expansion occurred in the periods 2001–2006 and 2006–2010. The analysis was strengthened by the incorporation of population and other socio-economic data. This study provides state authorities a means to examine correlations between urban growth, spatial expansion, and other socio-economic factors in order to not only assess patterns of urban growth but also become aware of potential environmental, social, and economic problems.
Duong H. Nong; Jefferson Fox; Tomoaki Miura; Sumeet Saksena. Built-up Area Change Analysis in Hanoi Using Support Vector Machine Classification of Landsat Multi-Temporal Image Stacks and Population Data. Land 2015, 4, 1213 -1231.
AMA StyleDuong H. Nong, Jefferson Fox, Tomoaki Miura, Sumeet Saksena. Built-up Area Change Analysis in Hanoi Using Support Vector Machine Classification of Landsat Multi-Temporal Image Stacks and Population Data. Land. 2015; 4 (4):1213-1231.
Chicago/Turabian StyleDuong H. Nong; Jefferson Fox; Tomoaki Miura; Sumeet Saksena. 2015. "Built-up Area Change Analysis in Hanoi Using Support Vector Machine Classification of Landsat Multi-Temporal Image Stacks and Population Data." Land 4, no. 4: 1213-1231.
Tomo’Omi Kumagai; Ryan G. Mudd; Thomas Giambelluca; Nakako Kobayashi; Yoshiyuki Miyazawa; Tiva Khan Lim; Wen Liu; Maoyi Huang; Jefferson Fox; Alan D. Ziegler; Song Yin; Sophea Veasna Mak; Poonpipope Kasemsap. How do rubber (Hevea brasiliensis) plantations behave under seasonal water stress in northeastern Thailand and central Cambodia? Agricultural and Forest Meteorology 2015, 213, 10 -22.
AMA StyleTomo’Omi Kumagai, Ryan G. Mudd, Thomas Giambelluca, Nakako Kobayashi, Yoshiyuki Miyazawa, Tiva Khan Lim, Wen Liu, Maoyi Huang, Jefferson Fox, Alan D. Ziegler, Song Yin, Sophea Veasna Mak, Poonpipope Kasemsap. How do rubber (Hevea brasiliensis) plantations behave under seasonal water stress in northeastern Thailand and central Cambodia? Agricultural and Forest Meteorology. 2015; 213 ():10-22.
Chicago/Turabian StyleTomo’Omi Kumagai; Ryan G. Mudd; Thomas Giambelluca; Nakako Kobayashi; Yoshiyuki Miyazawa; Tiva Khan Lim; Wen Liu; Maoyi Huang; Jefferson Fox; Alan D. Ziegler; Song Yin; Sophea Veasna Mak; Poonpipope Kasemsap. 2015. "How do rubber (Hevea brasiliensis) plantations behave under seasonal water stress in northeastern Thailand and central Cambodia?" Agricultural and Forest Meteorology 213, no. : 10-22.
Building on a series of ground breaking reviews that first defined and drew attention to emerging infectious diseases (EID), the ‘convergence model’ was proposed to explain the multifactorial causality of disease emergence. The model broadly hypothesizes disease emergence is driven by the co-incidence of genetic, physical environmental, ecological, and social factors. We developed and tested a model of the emergence of highly pathogenic avian influenza (HPAI) H5N1 based on suspected convergence factors that are mainly associated with land-use change. Building on previous geospatial statistical studies that identified natural and human risk factors associated with urbanization, we added new factors to test whether causal mechanisms and pathogenic landscapes could be more specifically identified. Our findings suggest that urbanization spatially combines risk factors to produce particular types of peri-urban landscapes with significantly higher HPAI H5N1 emergence risk. The work highlights that peri-urban areas of Viet Nam have higher levels of chicken densities, duck and geese flock size diversities, and fraction of land under rice or aquaculture than rural and urban areas. We also found that land-use diversity, a surrogate measure for potential mixing of host populations and other factors that likely influence viral transmission, significantly improves the model’s predictability. Similarly, landscapes where intensive and extensive forms of poultry production overlap were found at greater risk. These results support the convergence hypothesis in general and demonstrate the potential to improve EID prevention and control by combing geospatial monitoring of these factors along with pathogen surveillance programs.
Sumeet Saksena; Jefferson Fox; Michael Epprecht; Chinh C. Tran; Duong Nong; James H. Spencer; Lam Nguyen; Melissa L. Finucane; Vien D. Tran; Bruce A. Wilcox. Evidence for the Convergence Model: The Emergence of Highly Pathogenic Avian Influenza (H5N1) in Viet Nam. PLoS ONE 2015, 10, e0138138 .
AMA StyleSumeet Saksena, Jefferson Fox, Michael Epprecht, Chinh C. Tran, Duong Nong, James H. Spencer, Lam Nguyen, Melissa L. Finucane, Vien D. Tran, Bruce A. Wilcox. Evidence for the Convergence Model: The Emergence of Highly Pathogenic Avian Influenza (H5N1) in Viet Nam. PLoS ONE. 2015; 10 (9):e0138138.
Chicago/Turabian StyleSumeet Saksena; Jefferson Fox; Michael Epprecht; Chinh C. Tran; Duong Nong; James H. Spencer; Lam Nguyen; Melissa L. Finucane; Vien D. Tran; Bruce A. Wilcox. 2015. "Evidence for the Convergence Model: The Emergence of Highly Pathogenic Avian Influenza (H5N1) in Viet Nam." PLoS ONE 10, no. 9: e0138138.
Antje Ahrends; Peter M. Hollingsworth; Alan D. Ziegler; Jefferson Fox; Huafang Chen; Yufang Su; Jianchu Xu. Current trends of rubber plantation expansion may threaten biodiversity and livelihoods. Global Environmental Change 2015, 34, 48 -58.
AMA StyleAntje Ahrends, Peter M. Hollingsworth, Alan D. Ziegler, Jefferson Fox, Huafang Chen, Yufang Su, Jianchu Xu. Current trends of rubber plantation expansion may threaten biodiversity and livelihoods. Global Environmental Change. 2015; 34 ():48-58.
Chicago/Turabian StyleAntje Ahrends; Peter M. Hollingsworth; Alan D. Ziegler; Jefferson Fox; Huafang Chen; Yufang Su; Jianchu Xu. 2015. "Current trends of rubber plantation expansion may threaten biodiversity and livelihoods." Global Environmental Change 34, no. : 48-58.
Over the last decade considerable research has been conducted on the development and the impacts of large-scale economic land concessions for plantations in Laos and Cambodia. These studies have variously illustrated that concessions frequently result in serious negative impacts on local people and the environment, often leading to dramatic transformations of landscapes and livelihoods. As important as this research has been, these studies have largely focused on the immediate impacts of the “enclosure” process associated with gaining access to land by investors. In this study we take a different approach, investigating the implications of large-scale land concessions in southern Laos and northeastern Cambodia with regard to places outside of actual concession areas, both within the countries where the concessions are located and beyond. These links have been referred to as “teleconnections” or “telecoupling”, and adopting a “telecoupling” approach allows us to focus on particular relations between land-use change in one location and land-use change elsewhere, either nearby or distant, as the result of large-scale plantation development, both during the early plantation development period, and later when plantations are productive. It also provides opportunities to engage with Land Change Science (LCS) through Political Ecology (PE).
Ian G. Baird; Jefferson Fox. How Land Concessions Affect Places Elsewhere: Telecoupling, Political Ecology, and Large-Scale Plantations in Southern Laos and Northeastern Cambodia. Land 2015, 4, 436 -453.
AMA StyleIan G. Baird, Jefferson Fox. How Land Concessions Affect Places Elsewhere: Telecoupling, Political Ecology, and Large-Scale Plantations in Southern Laos and Northeastern Cambodia. Land. 2015; 4 (2):436-453.
Chicago/Turabian StyleIan G. Baird; Jefferson Fox. 2015. "How Land Concessions Affect Places Elsewhere: Telecoupling, Political Ecology, and Large-Scale Plantations in Southern Laos and Northeastern Cambodia." Land 4, no. 2: 436-453.
Annual total suspended solid (TSS) loads in the Mae Sa Catchment in northern Thailand, determined with an automated, turbidity-based monitoring approach, were approximately 62,000, 33,000, and 14,000Mg during the three years of observation. These loads were equivalent to basin yields of 839 (603-1170), 445 (217-462), and 192 (108-222) Mgkm-2 for the 74.16-km2 catchment during 2006, 2007, and 2008, respectively. The yearly uncertainty ranges indicate our loads may be underestimated by 38-43% or overestimated by 28-33%. In determining the annual loads, discharge (Q) and turbidity (T) values were compared against 333 hand-sampled total suspended solid concentrations (TSS) measured during 18 runoff events and other flow conditions across the three-year period. Annual rainfall varied from 1632 to 1934mm; and catchment runoff coefficients (annual runoff/annual rainfall) ranged from 0.25 to 0.41. Measured TSS ranged from 8 to 15,900mgl-1; the low value was associated with dry-season base flow; the latter, a wet-season storm. Storm size and location played an important role in producing clockwise, anticlockwise, and complex hysteresis in the Q-TSS relationship. Turbidity alone was a good estimator for turbidity ranges of roughly 10-2800NTU (or concentrations approximately 25-4000mgl-1). However, owing to hysteresis and high sediment concentrations that surpass the detection limits of the turbidity sensor during many annual storms, TSS was estimated best using a complex multiple regression equation based on high/low ranges of turbidity and Q as independent variables. Turbidity was not a good predictor of TSS fractions >2000μm. Hysteresis in the monthly Q-TSS relationship was generally clockwise over the course of the monsoon season, but infrequent large dry-season storms disrupted the pattern in some years. The large decrease in annual loads during the study was believed to be related to depletion of fine sediment delivered to the stream by several landslides occurring the year prior to the study. The study indicated the importance of monitoring Q and turbidity at fine resolutions (e.g., sub-hourly) to capture the TSS dynamics and to make accurate load estimations in this flashy headwater stream where hysteresis in the Q-TSS signature varied at several time scales
Alan D. Ziegler; Shawn G. Benner; Chatchai Tantasirin; Spencer H. Wood; Ross A. Sutherland; Roy C. Sidle; Nicholas Jachowski; Mike A. Nullet; Lu Xi Xi; Anond Snidvongs; Thomas Giambelluca; Jefferson Fox. Turbidity-based sediment monitoring in northern Thailand: Hysteresis, variability, and uncertainty. Journal of Hydrology 2014, 519, 2020 -2039.
AMA StyleAlan D. Ziegler, Shawn G. Benner, Chatchai Tantasirin, Spencer H. Wood, Ross A. Sutherland, Roy C. Sidle, Nicholas Jachowski, Mike A. Nullet, Lu Xi Xi, Anond Snidvongs, Thomas Giambelluca, Jefferson Fox. Turbidity-based sediment monitoring in northern Thailand: Hysteresis, variability, and uncertainty. Journal of Hydrology. 2014; 519 ():2020-2039.
Chicago/Turabian StyleAlan D. Ziegler; Shawn G. Benner; Chatchai Tantasirin; Spencer H. Wood; Ross A. Sutherland; Roy C. Sidle; Nicholas Jachowski; Mike A. Nullet; Lu Xi Xi; Anond Snidvongs; Thomas Giambelluca; Jefferson Fox. 2014. "Turbidity-based sediment monitoring in northern Thailand: Hysteresis, variability, and uncertainty." Journal of Hydrology 519, no. : 2020-2039.