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4 resultados encontrados para: AUTOR: Millones, Marco
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1.
Artículo
Hurricane disturbance mapping using MODIS EVI data in the southeastern Yucatán, Mexico
Schneider, Laura C. ; Rogan, John ; Christman, Zachary John (coaut.) ; Millones, Marco (coaut.) ; Lawrence, Deborah (coaut.) ; Schmook, Birgit Inge (coaut.) ;
Contenido en: Remote Sensing Letters Vol. 2, no. 3 (September 2011), p. 259-267 ISSN: 2150-704X
Resumen en: Inglés |
Resumen en inglés

This letter evaluated the use of Moderate Resolution Imaging Spectroradiometer (MODIS) 250 mEnhanced Vegetation Index (EVI) standard product data (MOD/ MYD13Q1 C5) to map the damage caused by Hurricane Dean (August 2007) to the forests in the Yucata´n Peninsula of Mexico using a two-step vetting procedure. Sequences of MODIS EVI 16-day composite products captured before and after the hurricane were compared against 93 field damage plots to select an appropriate set of pre- and post-damage data. Aqua pairwise combinations produced the highest damage detection overall accuracy compared with Terra (82.4% vs. 73.8%, respectively) because of advantageous timing of the Aqua EVI compositing, relative to the hurricane event. The most accurate EVI damage map (91.4% overall) revealed highest damage detection in Saffir–Simpson hurricane wind scale zone 5 (i.e. wind speed .248 km h-1, i.e. 95%), followed by 93% in zone 4 (210–249 km h-1) and 87% in zone 3 (178–209 km h-1). Results indicate that MODIS EVI products provide timely and accurate maps of hurricane damage in subtropical forests.


2.
- Artículo con arbitraje
Resumen en: Inglés |
Resumen en inglés

This research examines the spatio-temporal trends in Advanced Very High Resolution Radiometer (AVHRR) Global Inventory Modelling and Mapping Studies (GIMMS) normalized difference vegetation index (NDVI) time series to ascribe land use change and precipitation to observed changes in land cover from 1982 to 2007 in the Mexican Yucatán Peninsula, using seasonal trend analysis (STA). In addition to discrete land cover transitions across the study region, patterns of agricultural intensification, urban expansion and afforestation in protected areas have enacted changes to the seasonal patterns of apparent greenness observed through STA greenness parameters. The results indicate that the seasonal variation in NDVI can be used to distinguish among different land cover transitions, and the primary differences among these transitions were in changes in overall greenness, peak annual greenness and the timing of the growing season. Associations between greenness trends and precipitation were weak, indicating a human-dominated system for the 26 years examined. Changes in the states of Campeche, Quintana Roo and Yucatán appear to be associated with pasture cultivation, urban expansion-extensive cultivation and urban expansion-intensive cultivation, respectively.


3.
- Artículo con arbitraje
Resumen en: Inglés |
Resumen en inglés

This study explores the temporal and spatial variability and change in rainfall across southeastern Mexico and the mechanisms by which smallholder farmers adapt to this variability, especially droughts. Members of 150 households in 10 communities were interviewed to investigate adaptation strategies among swidden maize smallholders, linked to their perceptions of climate changes. Precipitation data from seven weather stations were analyzed for the 1973–2012 period. Precipitation anomalies were estimated to evaluate the annual and seasonal stability, deficit, or surplus; and linear regressions were used to evaluate trends. Then, these anomalies were linked to variation in reported agricultural practices. Weather station data show a considerable decline in precipitation in most of the study area, coupled with increased drought frequency and an increase in negative anomalies in recent years. Surveys revealed several mechanisms of adaptation, including adjustment of the agricultural calendar (e.g. delaying planting, combined with planting a greater number of varieties of maize), water storage, and livelihood diversification both within and outside of agriculture. These adaptive mechanisms are responsive to demonstrated climatic change over the past 40 years, though globalization affects Mexico's agrarian economy, and farmers likely respond to a combination of economic and climatic factors. Understanding how resource- and climate-dependent swidden farmers respond to co-occurring climatic and economic changes is essential for effective adaptation policy design.


4.
Artículo
Using food flow data to assess sustainability: land use displacement and regional decoupling in Quintana Roo, Mexico
Millones, Marco ; Parmentier, Benoit (coaut.) ; Rogan, John (coaut.) ; Schmook, Birgit Inge (coaut.) ;
Contenido en: Sustainability ISSN: 2071-1050
PDF
Resumen en: Inglés |
Resumen en inglés

Food flow data provide unique insights into the debates surrounding the sustainability of land based production and consumption at multiple scales. Trade flows disguise the spatial correspondence of production and consumption and make their connection to land difficult. Two key components of this spatial disjuncture are land use displacement and economic regional decoupling. By displacing the environmental impact associated with food production from one region to another, environmental trajectories can falsely appear to be sustainable at a particular site or scale. When regional coupling is strong, peripheral areas where land based production occurs are strongly linked and proximate to consumption centers, and the environmental impact of production activities is visible. When food flows occur over longer distances, regional coupling weakens, and environmental impact is frequently overlooked. In this study, we present an analysis of a locally collected food flow dataset containing agricultural and livestock products transported to and from counties in Quintana Roo (QRoo). QRoo is an extensively forested border state in southeast Mexico, which was fully colonized by the state and non-native settlers only in the last century and now is home to some of the major tourist destinations. To approximate land displacement and regional decoupling, we decompose flows to and from QRoo by (1) direction; (2) product types and; (3) scale. Results indicate that QRoo is predominantly a consumer state: incoming flows outnumber outgoing flows by a factor of six, while exports are few, specialized, and with varied geographic reach (Yucatan, south and central Mexico, USA).

Imports come predominantly from central Mexico. Local production in QRoo accounts for a small portion of its total consumption. In combining both subsets of agricultural and livestock products, we found that in most years, land consumption requirements were above 100% of the available land not under conservation in QRoo, suggesting unsustainable rates of land consumption in a ´business as usual´ scenario. We found evidence of economic regional decoupling at the state level.